mechatron

MECHATRON ROVER A COMPLETE DISCRIPTION OF ROVER

BY G.VIVEK CHARY

My special thanks to k.karthik

TO THE MEMORY OF MY PARENTS My mother sea waves,goldensand,pilgrims faith , sanjeeva reddy street, all merge into one, my mother! You come to me like heaven’s caring arms.

I remember the wars days when life was challenge and toil – Miles to walk, hours before sunrise, Walking to take lessons from the teacher near the temple.

Again miles to the teaching school, Few hours after sunrise, going to school, Evening, business time before study at night.

All this pain of a young boy, My mother you transformed into pious strength With kneeling and bowing five times For the grace of the almightily only, my mother.

Young strong piety is your children’s strength, You always shared your best with whoever needed the most, You always gave, and gave with faith in him.

Mother! My mother!

When at midnight I woke with tears falling on my knee

You knew the pain of your child ,my mother.

Your caring hands, tenderly removing the pain Your love, your care, your faith gave me strength.

We will meet again on the great judgment day, my mother!

G VIVEK CHARY

CONTENTS Preface

--

Acknowldgements

--

Introduction

--

Chapter 1: LUNOKHOD SERIES

--

Chapter 2: MARS SERIES

--

Chapter 3:

THE LUNAR ROVING VEHICLE

--

Chapter 4: MARS RECONNAISSANCE ORBITER -Chapter 5: MARS EXPLORATION ROVER

--

Chapter 6: ABOUT PHOENIX

--

Chapter 7: ABOUT VIKING 2

--

PrEfaCE: This book is written by focusing on the students who are interested in rovers. Different types of rover are described in this book and in which year it is launched , its history,instruments used,images sent by them etc is also focused in this book.

INTRODUCTION: MARS IN SOCIETY AND CULTURE

Mars has always played a significant role in human society. The early Greeks Noted that unlike the other planets, Mars sometimes seemed to reverse its Direction across the sky. This “contrary� motion suggested disorder and anarchy To the Greeks, which, along with its reddish color, led them to name the Planet after Ares, their god of war. The Romans later changed the planets Name to that of their god of war, Mars, and the name have remained ever since. Sun would rotate around the smaller Earth. He proposed instead that the Earth revolves around the Sun. He was condemned for heresy because of his theory and all of his writings were rounded up and destroyed. The only reason we know anything about Aristarchus at all is because he is mentioned in the writings of the great mathematician Archimedes. No other scientist was willing to risk the wrath of the Church by mentioning

the astronomer’s work. In 1543, nearly 2,000 years later, however, Aristarchus’ theory was taken up by Polish doctor, lawyer, and parttime astronomer Nicolaus Copernicus.

Copernicus’ careful observations could not be explained by Ptolemy’s theory. Only if the Sun were at the center of the Solar System could his data make sense. Once again, because of new observations, new science and a new worldview was born.

The New Scientists:

Mars played a major role in the controversy.

Even Copernicus’ theory could not explain the strange motions of Mars. In 1600 Tycho Brahe had undertaken the careful study of Mars’ orbit. Tycho was perhaps the greatest

observational astronomer the world has ever known. We can make more Accurate observations today only because we have more accurate instruments. Tycho was world famous, a rock star of science who toured the Palaces of kings and other nobility all over Europe. Tycho had given his student, a German mathematician named Johannes Kepler, the task of creating a mathematical description of Mars’ orbit. Tycho, however, was very protective of his data, the table.

When Tycho finally died several Years later, Kepler broke into Tycho’s safe and stole all of his data. Tycho’s family demanded the documents be returned, and Kepler did so – but only after he had made exact copies of all of the precious data.

Kepler, like most of his fellow scientists, felt certain that the planets traveled in perfect circles. After years of struggling with Tycho’s observations of Mars, however, he finally reached the inescapable conclusion that all the work done before him was wrong: the planets move in ellipses, not circles. In addition, he discovered two other laws of

planetary motion that he published in 1609.

Thanks to Mars, we now understood not only its motion, but the motion of the entire Solar System as well. In 1634, Kepler published a book called The Dream, in which he described a fanciful flight from the Earth to the as are many scientists today. He would throw out an observation over dinner in casual conversation, which Kepler would frantically scrawl down in a notebook that he kept under Moon. It was one of the first works of science fiction. Science fiction books have spurred generations of people to wonder about the stars and the planets that travel through the heavens. By the end of the 19th century, however, improved telescopes showed that the Moon was a barren, desolate place, a place where no life could possibly exist. Mars, however, was still a fuzzy disk in even the best telescopes. Science fiction authors, scientists, and the imaginations of the general public turned away from the Moon and looked instead to the Red Planet. In 1877, Italian astronomer Giovanni Schiaparelli observed a series of lines that seemed to cross most of the surface of Mars. In his notes, he called

these lines canali, an Italian word that means “channels”. American amateur astronomer Percival Lowell, however, translated the word as “canals”, a very similar meaning, but one that has very different implications: “canals” implies intelligence. Lowell believed that Schiaparelli had discovered the engineering works of a dying Martian society desperately trying to bring water from the Martian icecaps to the equatorial lands. Lowell was so excited by the discovery that he had a state-of-the-art observatory Built in Flagstaff, AZ, specifically to study Mars. His writings ignited the imagination of generations of people around the world, including great science fiction authors such as Edgar Rice Burroughs (the Barsoom series of 11 novels), Ray Bradbury (The Martian Chronicles), and H.G. Wells (The War of the Worlds). Wells’ work was made even more popular when Orson Welles (no relation to H.G. Wells) and his Mercury Theater on the Air performed the most famous radio play in American history.

To celebrate Halloween of 1938, Welles adapted The War of Worlds, a tale of a Martian invasion of the Earth, into a radio broadcast.

Story events were presented as “news broadcasts” reporting New York City in flames and unstoppable aliens destroying everything in their paths. Millions of people, who tuned in to the play late, thought the broadcasts were real and fled their homes in terror of the “invasion”. Most had taken to the streets in panic and never heard the play’s end and Welles’ wish for them to have a happy Halloween. NBC issued a public apology the next day; Welles became one of Hollywood’s most successful actors. Mars, and the possibility of life there, was so firmly ingrained in the minds of the public that no one questioned that the events of that night might not have actually been real. Mars has always had this power over us. Today scientists know that Mars in its current form probably cannot support life as we know it.

Spacecraft sent to Mars have found no trace of Lowell’s “canals” or of his dying civilization.

But was Mars always as it is now? Data returned from our Mars spacecraft show us that it almost certainly was not. At some time in the past, Mars was much warmer and wetter than it is today. What happened to

Mars? Did it once have life? Where did all the water on Mars go? Could Earth also change as Mars has? These are just a few of the questions scientists hope to answer, important questions that you will also help to answer as you begin your exploration in the Mars Student Imaging Project.

BASIC CONCEPT OF MARS ROVER: a rover planetary rover is a space exploration vehicle designed to move across the surface of the planet or other celestial body. Some rovers have been designed to transport members of the human spaceflight crew,

other has been partially, or fully autonomous robort.rover usually arrives at the planetary surface on a Lander style space craft.

ADVANTAGES AND DIS ADVANTAGES OF ROVER: their advantages over orbiting space craft are that they can make observations to a microscopic level and can conduct physical experimentation. Disadvantages of rovers compared to orbiters are the higher chance of failure, due to a small area around a landing site which itself is only approximately anticipated.

FEATURES: Rovers arrives on space craft and are used in conditions very distinct from those on the earth, which makes some demands on their design.

RELIABILITY: rovers have to withstand high levels of acceleration, high and low temperatures, pressures, dust, corrosion, cosmic rays, remaining functional without repair for a needed.

COMPACTNESS: rovers are usually packed for placing in a space craft, because it has limited capacity, and have to be deployed.

AUTONOMY: rovers which land on celestial bodies far from the earth, such as the mars exploration rovers cannot be remotely controlled in real time. Since the speed at which radio signals travel is far too slow .for real time or near real time communication though they still require Human input for identifying promising targets in the distance to which to drive and determination how to position itself to maximize solar energy.

CHAPTER 1: LUNOKHOD SERIES LUNOKHOD 1A: The soviet rover was intended to be first roving remote controlled robot on the moon, but crashed during a failed start of the launcher 19 Feb 1969.

LUNOKHOD 1: The lunokhod 1 rover landed on moon in nov1970.it was the first roving remote controlled robot to land on any celestial body. the soviet union lunched lunokhod1 abroad the luna17 spacecraft on nov 1970.and it entered lunar orbit on nov15.the space craft soft landed in the sea of rains region on nov 17.the Lander had dual ramps from which lunokhod1 could descend to the lunar surface, which it did at 06:28ut from nov 17 1970 to nov 22 1970 the rover 197mts and during 10 communication sessions returned 14 close up pictures of the moon and 12 panoramic views. It also analyzed the lunar soil. the last successful communications sessions with lunokhod 1 was on September 14 1971 having worked for 11 months.lunokhod 1 held the durability record for space

rovers for more than 30 years, until a new record was set by the mars explorations’ rovers.

ROVER DISCRIPTION: lunokhod 1 was a lunar vehicle formed of a tub-like compartment with a large convex lid eight independently powered wheels. Its length was 2.3 meters .lunokhod was equipped with a cone shaped antenna, a highly directional helical antenna, four television cameras, and special extendable devices to test the lunar soil for soil density and mechanical orient tests. an x-ray spectrometer, an x-ray telescope, cosmic ray detectors and a laser device were also included. the vehicle was powered by batteries which were recharged during the lunar day by a solar cell array mounted on the underside of the lid. To be able to work in vacuum a special fluoride based lubricant was used for the

mechanical parts and the electric motors but actually operated for eleven lunar days.

CURRENT LOCATION: the final location of lunokhod 1 was uncertain until 2010,as lunar laser ranging experiments had failed to detect a return signal from it since 1971.on march 17,2010,albert abdrakhimov found both the Lander and the rover in lunar reconnaissance orbiter image M114185541RC.in April 2010,the apache point observatory lunar laser-ranging operation team from the university of California at san diego used the lro images to locate the orbiter closely enough for laser ranger measurements. on April 22,2010 and days following the team successfully measured distances then pin point the current location of lunokhod 1 to within 1 meter.apollo is now using lunokhod 1 reflector for experiments, as they discovered, to their surprise, that it was returning much more light than other reflector on the moon. According to nasa press relase,apollo reacher tom Murphy said, “WE GOT ABOOUT 2000 PHOTONS FROM LUNOKHOD 1 ON OUR FIRST TRY.AFTER ALMOST

40 YEARS OF SILENCE ,THIS ROVER STILL HAS A LOT TO SAY.�

By November 2010, the location of the rover had been determined to within about a centimeter. The location near the limb of the moon, combined with the ability to range the rover even when it is in sunlight, promises to be particularly useful for determining aspects of the earth moon system In a report released in May 2013, french scientists at the Cote d’azur observatory led by jean-maries tore reported replicating the 2010 laser ranging experiments by reconnaissance orbiter. In both cases, laser pulse was returned from the lunokhod 1 retro reflector.

LUNOKHOD 2:

The lunokhod 2 was the second of two unmanned lunar rovers landed on the moon by unmanned lunar rovers landed on the moon by the soviet union as part of the lunokhod program. The rover became operational on the moon on 16 Jan 1973.it was the second roving remote controlled robot to land on any celestial body. The soviet union launched lunokhod 2 aboard the Luna 21 space craft on Jan 8 1973 and it entered lunar orbit on jan12.the space craft soft landed in the eastern edge of the mars serentot region on Jan 15.lunokhod 2 descended from the Landers dual ramps to the lunar surfaces at 01:14 on 16 jan.lunokhod 2 operated for about 4 months. Covered 37kmts of terrain, including hilly upland areas and hills and sent back 86 panoramic images and over 80,000 TV pictures based on a wheel rotations lunokhod 2 was thought to have covered 37 kmts but Russian scientists at the Moscow state university of geodesy and cartography have revised that an estimated distance of about 42.1 to42.2 km based on lunar reconnaissance orbiter images of the lunar surface.

LUNOKHOD 3

The soviet rover was intended to be the third roving remote-controlled robot on the moon in 1977.the mission was funding. Although the rover was built.

CHAPTER2: MARS SERIES Mars3: it was unmanned space probe of the soviet mars program which spanned the years between 1960 and 1973.mars 3 was launched nine days after its twin space craft mars2.the probes were identical space craft, each consisting of an orbiter and an attached lander.after mars 2 crash-landed on the Martian surface, mars 3 Lander became the first spacecraft to attain soft landing on mars. Both probe launched by proton-k rockets with blocked upper stages.

ORBITER: the primary purpose of the orbiter was to study the topography of the surface; analyze its soil composition; measure various properties of the atmosphere; moniter”solar radiation, the solar wind, and the interplanetary and Martian magnetic fields. In addition, it served as a “communications relay to send signals from the Lander to earth.”

The orbiter suffered from a partial loss of fuel and did not have enough to put itself into a planned 25 hour orbiter. The engine instead performed a truncated burn to put the space craft into a highly-elliptical long period orbiter about mars.

By coincidence a particularly large dust storm on mars adversely affected the mission. When mariner 9 arrived and successfully orbited mars on 14 November 1971,just two weeks prior to mars 2 and mars 3,planetary scientists were surprised to find the atmosphere was thick with “a planet-wide robe of dust, the largest storm ever observed. “the surface was totally obscured. Unable to reprogram the mission computers, both mars 2 and mars 3 dispatched their Landers immediately, and the orbiters used up a significant portion of their available data resources in snapping images of the featureless dust clouds below, rather than the surface mapping intended.

The mars 3 orbiter sent back data covering the period from December 1971 to march 1972, although transmissions continued through august. It was announced that mars 3 had completed their mission by 22 august 1972.it was announced that mars 3 had

completed their mission by 22 august 1972,aafter 20 orbits. The probe, combined with mars 2,sent back a total pictures. The images and data revealed mountains as high as 22km, atomic hydrogen and oxygen in the upper atmosphere, surface temperatures ranging from -110c to +13c, surface pressures of 5.5 to 6mb,water vapor concentrations 5000 times less than in earth’s atmosphere ,the base of the ionosphere starting at 80 to 110 km altitude, and grains from dust storms as high as 7 km in the atmosphere. The images and data enabled creation of surface relief maps, and gave information on the Martian gravity and magnetic fields.

CHAPTER 3: THE LUNAR ROVING VEHICLE The Lunar Roving Vehicle (LRV) or lunar rover was a battery-powered four-wheeled rover used on the Moon in the last three missions of the American Apollo program (15, 16, and 17) during 1971 and 1972. It was popularly known as the moon buggy, a play on the phrase "dune buggy".

The LRV was transported to the Moon on the Apollo Lunar Module (LM) and, once unpacked on the surface, could carry one or two astronauts, their equipment, and lunar samples. The three LRVs remain on the moon.

History:

The concept of a lunar rover predated Apollo, with a 1952–1954 series in Collier's Weekly magazine

by Wernher von Braun and others, "Man Will Conquer Space Soon!" In this, von Braun described a six-week stay on the Moon, featuring 10-ton tractor trailers for moving supplies.

In 1956, Mieczyslaw G. Bekker published two books on land locomotion.[1] At the time, Bekker was a University of Michigan professor and a consultant to the U.S. Army Tank-Automotive Command's Land Locomotion Laboratory. The books provided much of the theoretical base for future lunar vehicle development.

With pressure from Congress to hold down Apollo costs, Saturn V production was reduced, allowing only a single booster per mission. It would then be necessary for any roving vehicle to be carried on the same Lunar Module as transporting the astronauts. In November 1964, ALSS was put on indefinite hold, but Bendix and Boeing were given study contracts for small rovers under the LSSM

program. The name of the Lunar Excursion Module was changed to simply the Lunar Module, indicating that the capability for powered "excursions" away from a lunarLander base did not yet exist. There could be no SHELAB — the astronauts would work out of the LM — and the LTV accommodating two persons took the name Local Scientific Surface Module (LSSM). MSFC was also examining unmanned robotic rovers that could be controlled from the Earth.

During 1965 and 1967, the Summer Conference on Lunar Exploration and Science brought together leading scientists to assess NASA's planning for exploring the Moon and to make recommendations. One of their findings was that the LSSM was critical to a successful program and should be given major attention. At MSFC, von Braun established the Lunar Roving Task team, and in May 1969, NASA selected the Lunar Roving Vehicle (LRV) for use in manned lunar missions and approved the Manned Lunar Rover Vehicle Program as a MSFC hardware development. Saverio F. "Sonny" Morea was named the LRV program manager.

On 11 July 1969, just before the successful Moon landing of Apollo 11, a request for proposal for the final development and building the Apollo LRV was released

by MSFC. Boeing, Bendix, Grumman, and Chrysler

submitted proposals. Following three months of proposal evaluation and negotiations, Boeing was selected as the Apollo LRV prime contractor on 28 October 1969.

Boeing would manage the LRV project under Henry Kudish in Huntsville, Alabama. As a major subcontractor, General Motors' Defense Research Laboratories in Santa Barbara, California, would furnish the mobility system (wheels, motors, and suspension); this effort would be led

by Ferenc Pavlics. Boeing in Seattle, Washington, would furnish the electronics and navigation system. Vehicle testing would take place at the Boeing facility in Kent, Washington, and the chassis manufacturing and overall assembly would be at the Boeing facility in Huntsville.

The LRV was developed in only 17 months and performed all its functions on the Moon with no major anomalies. Scientist-astronaut Harrison Schmitt of Apollo 17 said, "The Lunar Rover proved to be the reliable, safe and flexible lunar exploration vehicle we expected it to be. Without it, the major scientific discoveries of Apollo 15, 16, and 17 would not have been possible; and our current understanding of lunar evolution would not have been possible."

The LRVs experienced some minor problems. The rear fender extension on the Apollo 16 LRV was lost during the mission's second extra-vehicular activity (EVA) at station 8 when John Young bumped into it while going to assist Charles Duke. The dust thrown up from the wheel covered the crew, the console, and the communications equipment. High battery temperatures and resulting high power consumption ensued. No repair attempt was mentioned.

The Apollo Lunar Roving Vehicle was an electricpowered vehicle designed to operate in the low-gravity vacuum of the Moon and to be capable of traversing the lunar surface, allowing the Apollo astronauts to extend the range of their surface extravehicular activities. Three LRVs were used on the Moon, one on Apollo 15 by astronauts David Scott and Jim Irwin, one on Apollo 16

by John Young and Charles Duke, and one on Apollo 17

by Eugene Cernan and Harrison Schmitt. The mission commander served as the driver, occupying the left-hand seat of each LRV. Features are available in papers by Morea, Baker, and Kudish.

Mass and payload: The Lunar Roving Vehicle had a mass of 463 lb (210 kg), which resulted in a lunar weight of 77.2 lbf (35.0 kgf) and was designed to hold a payload of an additional 1,080 lb (490 kg) on the lunar surface. The frame was 10 ft (3.0 m) long with a wheelbase of 7.5 ft (2.3 m). The height of the vehicle was 3.6 feet (1.1 m). The frame was made of aluminum alloy 2219 tubing welded assemblies and consisted of a three-part chassis that was hinged in the center so it could be folded up and hung in the Lunar Module Quadrant 1 bay. It had two side-by-side foldable seats made of tubular aluminum with nylon webbing and aluminum floor panels. An armrest was mounted between the seats, and each seat had adjustable footrests and a Velcro seat belt. A large mesh dish antenna was mounted on a mast on the front center of the rover. The suspension consisted of a double horizontal wishbone with upper and lower torsion bars and a damper unit

between the chassis and upper wishbone. Fully loaded, the LRV had a ground clearance of 14 inches (36 cm).

CHAPTER 4: MARS RECONNAISSANCE ORBITER Mars reconnaissance orbiter is a multipurpose space craft designed to conduct reconnaissance and exploration of mars from orbit. The us$720 million spacecraft was built by Lockheed martin under the supervision of the jet propulsion laboratory. The mission is managed by the jpl at California institute of technology, a Canada Flintridge,california,for the nasa science mission directorate,Washington,d.c.

it was launched august 12,2005,andattained Martian orbit on march 10,2006,in November 2006,after five months of aero braking .it entered its final science orbit and began its primary science phase. As MROs entered orbit it joined five other active spacecraft which were either in orbit or on the planet surface: mars global surveyor, mars express, mars odyssey, and two mars

exploration rovers; at the time a record for the most operational spacecraft in the immediate vicinity of mars.

PRE-LAUNCH: MRO was one of two missions being considered for the 2003 mars launch window; however, during the proposal process the orbiter lost against what became known as the mars exploration rovers. The orbiter mission was rescheduled for launch in 2005, and NASA announced its final name, mars reconnaissance orbiter, on October 26, 2000.

MRO is modeled after NASA’s highly successful mars global surveyor to conduct surveillance of mars from orbiter. Early specifications of the satellite included a large camera to take high resolution pictures of mars. In this regard, Jim graven, the mars exploration program scientist for NASA, proclaimed that MRO would be a microscope in orbit. The satellite was also to include a visible near infrared spectrograph.

On October 3, 2001, NASA chose Lockheed martin as the primary contractor for the spacecraft’s fabrication .by the end of 2001 all of the mission’s instruments were selected. There were no major setbacks during MRO’s construction, and the spacecraft was moved to john f.kennedy space center on May 1, 2005 to prepare it for launch.

MISSION OBJECTIVES: MRO science operations were initially scheduled to last two earth years, from November 2006 to November 2008.one of the missions main goals is to map the Martian landscape with its high resolution cameras in order to choose landing sites for future surface missions. The MRO played an important role in choosing the landing site for future surface missions. The MRO played an important role in choosing the landing site of the phoenix lander, which explored the Martian arctic in green valley .the initial site chosen hires’ and the mars odyssey’s themis a new site was chosen. Mars science laboratory, a highly maneuverable rover, also had its landing site inspected. The MRO provided critical navigation data during their landings and acts as a telecommunications relay.

DISCOVERIES AND PHOTOGRAPHS: WATER ICE IN ICE CAP MEASURED: results published in 2009 of radar measurements of the north polar ice cap determined that the volume of water ice in the cap is 821,000 cubic kilometer, equal to 30% of the earth’s Greenland ice sheet.

ICE EXPOSED IN NEW CRATERS: water ice excavated by an impact crater that formed between January and September 2008.the ice was identified spectroscopic ally using CRISM.

An article in the journal science in September 2009, reported that some new craters on mars have excavated relatively pure water ice. After being exposed, the ice gradually fades as it sublimates away. These new craters were found and dated by the ctx camera, and the

identification of the ice was confirmed with the compact imaging spectrometer on board the mars reconnaissance orbiter. The ice was found in a total of 5 locations. Three of the locations are in the cebrenia quadrangle.

CHAPTER 5: MARS EXPLORATION ROVER NASA’s mars exploration rover mission is an ongoing robotic space mission involving two rovers. Spirit and opportunity, exploring the planet mars. It began in 2003 with the sending of the two rovers-MER-A spirit and MER-B opportunity to explore the Martian surface and geology.

The missions scientific objective was to search fokr and characterize a wide range of rocks and soils that hold clues to past water activity on mars .the mission is part of NASA’s mars exploration program, which includes three previous successful Landers; the two Viking program Landers in 1976 and mars pathfinder probe in 1997.

The total cost of building ,launching, landing and operation the rovers on the surface for the initial 90martian day primary mission was US $820 million .since the rovers have continued to funcrion beyond their initial 90 sol primary mission, they have each received five mission extensions .the fifth mission extension was granted in October 2007 ,ran to the end of 2009.the total cost of the first four mission extensions was $104 million ,and the fifth mission extension is expected to cost at least $20 million.

On may 1,2009 ,during its fifth mission extension, spirit become stuck in soft soil on mars, after nearly nine months of attempts to get the rover back on track, including using test rovers on earth,NASA announced on January 26,2010 that was being re tasked as a stationary

science platform. This mode would enable spirit to assist scientists in ways that a mobile platform could not, such as detection “wobbles� in the planet’s rotation that would indicate a liquid core.jet propulsion laboratory lost contact with spirit after last hearing from the rover on march 22, 2010 and continued attempts to regain communications lasted until may 25, 2011, bringing the elapsed mission time to 6 years 2 months 19 days, or over 25 times the original planned mission duration.

In recognition of the vast amount of scientific information amassed by both rovers, two asteroids have been named in their honor: 37452 spirit and 39382 opportunity .the mission is managed for NASA by the jet propulsion laboratory, which designed, built, and is operating the rovers.

Objectives: the scientific objectives of the mars exploration rover mission are to • Search for and characterize a variety of rocks and soils that hold clues to past water activity. In particular, samples sought include those that have minerals deposited by water related processes such as precipitation, evaporation, sedimentary cementation, or hydrothermal activity.

• Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites.

• Determine what geologic processes have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion,sedimentation,hydrothermal mechanisms ,volcanism, and cratering .

• Perform calibration and validation of surface observations made by mars reconnaissance orbiter instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit.

Spacecraft design:

Cruise stage: the cruise stage is the component of the spacecraft that is used for travel from travel from earth to mars. It is very similar to the mars pathfinder in design and is approximately 2.65meters in diameter and 1.6m tall, including the entry vehicle The primary structure is aluminum with an outer ring of ribs covered by the solar panels, which are about 2.65m in diameter. Divided into five section, the solar arrays can provide up to 600 watts of power near earth and 300w at mars.

Heaters and multi-layer insulation keep the electronics “warm�. a Freon system removes heat from the flight computer and communication hardware inside the rover so they do not overheat.

Cruise avionics systems allow the flight computer ro interface with other electronics, such as the sun sensors, star scanner and heaters.

Navigation: the star scanner and sun sensor allowed the spacecraft to know its orientation in space by

analyzing the position of the sun and other stars in relation to itself. Sometimes the craft could be slightly off course; this was expected, given the 500 million kilometer journey .thus navigators planned up to six trajectory correction maneuvers, along with health checks.

To ensure the spacecraft arrived at mars in the right place for its landing, two light-weights, aluminumlined tanks carried about 31kg of hydrazine propellant. Along with cruise guidance and control systems, the propellant allowed navigators to keep the spacecraft on course. Burns and pulse firings of the propellant allowed three types of maneuvers: • An axial burn uses pairs of thrusters to change spacecraft velocity; • A lateral burn uses two “thruster clusters” to move the spacecraft “sideways “through seconds long pulses; • Pulse mode firing uses coupled thruster pairs for spacecraft precession maneuvers

Communication: the spacecraft used a high frequency x band radio wavelength to communicate, which allowed for less power and smaller antennas than many older craft, which used s band.

Navigators sent commands through two antennas on the cruise stage; a cruise low gain antenna mounted inside the inner ring, and a cruise medium –gain antenna in the outer ring. The low gain antenna was used close to earth .it is Omni directional, so the transmission power that reached earth fell faster with increasing distance.

As the craft moved closer to mars, the sun and earth moved closer in the sky as viewed from the craft, so less energy reached earth. the spacecraft then switched to the medium gain antenna ,which directed the same amount of transmission power into a tighter beam toward earth. During flight, the spacecraft was spin stabilized with a spin rate of two revolutions per minute, periodic updates kept antennas pointed towards earth and solar panels towards the sun.

Aero shell: the aero shell maintained a protective covering for the Lander the seven month voyage to mars .together with the Lander and the rover, it constituted the “entry vehicle”. its main purpose was to protect the Lander and the rover inside it from the intense heat of entry into the thin Martian atmosphere. It was based on the mars pathfinder and mars Viking designs.

Scientific instrumentation: the rover has various instruments. Three mounted on one assembly: • Panoramic camera, for determining the texture, color, mineralogy, and structure of the local terrain.

• Navigation camera that has higher field of view but lower resolution and is monochromatic, for navigation and driving.

• A mirror for the miniature thermal emission spectrometer, which identifies promising rocks and soils for closer examination, and determines the processes that formed them.

It was built by Arizona state university.

The cameras are mounted 1.5 mts high on the pan cam mast assembly. One motor turns the assembly horizontally a whole revolution .another points the cameras vertically, at most straight up or down. a third motor points the mini test ,up to 30degree above the horizon and 50 degree below. The assembly was built by ball aerospace and technologies corp, boulder, Colorado,as was the high gain antenna gimbals.

CHAPTER 6: ABOUT PHOENIX Phoenix was a robotic spacecraft on a space exploration mission on Mars under the Mars Scout Program. The Phoenix Lander descended on Mars on May 25, 2008. Mission scientists used instruments aboard the Lander to search for environments suitable for microbial life on Mars, and to research the history of water there.

The multi-agency program was headed by the Lunar and Planetary Laboratory at the University of Arizona, under the direction of NASA's Jet Propulsion Laboratory. The program was a partnership of universities in the United States, Canada, Switzerland, Denmark, Germany, the United Kingdom, NASA, the Canadian Space Agency, the Finnish Meteorological Institute, Lockheed Martin Space Systems, MacDonald Dettwiler & Associates (MDA) and other aerospace companies.[2] It was the first mission to Mars led by a public university in

NASA history. It was led directly from the University of Arizona's campus in Tucson, with project management at the Jet Propulsion Laboratory in Pasadena, Calif., and project development at Lockheed Martin in Denver, Colorado. The operational funding for the mission extended through November 10, 2008.

Phoenix was NASA's sixth successful landing out of seven attempts and was the first successful landing in a Martian polar region. The Lander completed its mission in August 2008, and made a last brief communication with Earth on November 2 as available solar power dropped with the Martian winter. The mission was declared concluded on November 10, 2008, after engineers were unable to re-contact the craft. After unsuccessful attempts to contact the Lander by the Mars Odyssey orbiter up to and past the Martian summer solstice on May 12, 2010, JPL declared the Lander to be dead. The program was considered a success because it completed all planned science experiments and observations.

Program overview: The mission had two goals. One was to study the geologic history of water, the key to unlocking the story of past climate change. The second was evaluating past or potential planetary habitability in the ice-soil boundary. Phoenix’s instruments were suitable for uncovering information on the geological and

possibly biological history of the Martian Arctic. Phoenix was the first mission to return data from either of the poles, and contributed to NASA's main strategy for Mars exploration, "Follow the water."

The primary mission was anticipated to last 90 sols (Martian days) – just over 92 Earth days.

However, the craft exceeded its expected operational lifetime by a little over two months before succumbing to the increasing cold and dark of an advancing Martian winter. Researchers had hoped that the Lander would survive into the Martian winter so that it could witness polar ice developing around it – perhaps up to 1 meter of solid carbon dioxide ice could have appeared. Even had it survived some of the winter, the intense cold would have prevented it from lasting all the way through. The mission was chosen to be a fixed Lander rather than a rover because: •

•

•

costs were reduced through reuse of earlier equipment; the area of Mars where Phoenix landed is thought to be relatively uniform and thus traveling is of less value; and The equipment weight that would be required to allow Phoenix to travel can instead be dedicated to more and better scientific instruments.

The 2003–2004 observations of methane gas on Mars were made remotely by three teams working with separate data. If the methane is truly present in the atmosphere of Mars, then something must be producing it on the planet now, because the gas is broken down by radiation on Mars within 300 years, therefore the importance to search for biological potential or habitability of the Martian arctic's soils. Methane could also be the product of a geochemical process or the result of volcanic or hydrothermal activity. Other future missions may enable us to discover whether life does indeed exist on Mars today.

History of the program: While the proposal for Phoenix was being written, the Mars Odyssey Orbiter used its gamma ray spectrometer and found the distinctive signature of hydrogen on some areas of the Martian surface, and the only plausible source of hydrogen on Mars would be water in the form of ice, frozen below the surface. The mission was therefore funded on the expectation that Phoenix would find water ice on the arctic plains of Mars. In August 2003 NASA selected the University of Arizona "Phoenix" mission for launch in 2007. It was hoped this would be the first in a new line of smaller, low-cost, Scout missions in the agency's exploration of Mars program. The selection was the result of an intense two-year competition with proposals from other institutions. The $325 million

NASA award is more than six times larger than any other single research grant in University of Arizona history.

Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory, as Principal Investigator, along with 24 Co-Investigators, were selected to lead the mission. The mission was named after the Phoenix, a mythological bird that is repeatedly reborn from its own ashes. The Phoenix spacecraft contains several previously built components. The Lander used for the 2007–08 mission is the modified Mars Surveyor 2001 Lander(canceled in 2000), along with several of the instruments from both that and the previous unsuccessful Mars Polar Lander mission. Lockheed Martin, which built the Lander, had kept the nearly complete Lander in an environmentally controlled clean room from 2001 until the mission was funded by the NASA Scout Program.

A comparison of sizes for the Sojourner, the Mars Exploration Rovers, the Phoenix Lander and the Mars Science Laboratory.

Phoenix was a partnership of universities, NASA centers, and the aerospace industry. The science instruments and operations were a University of Arizona responsibility. NASA's Jet Propulsion Laboratory in Pasadena, California, managed the project and provided mission design and control. Lockheed Martin

Space Systems, Denver, Colorado, built and tested the spacecraft. The Canadian Space Agency provided a meteorological station, including an innovative Laserbased atmospheric sensor. The co-investigator institutions included Malin Space Science Systems (California), Max Planck Institute for Solar System Research (Germany), NASA Ames Research Center (California), NASA Johnson Space Center (Texas), MDA (Canada), Optech Incorporated (Canada), SETI Institute, Texas A&M University, Tufts University, University of Colorado, University of Copenhagen (Denmark), University of Michigan, University of Neuch창tel (Switzerland), University of Texas at Dallas, University of Washington, Washington University in St. Louis, and York University (Canada). Scientists from Imperial College London and the University of Bristol provided hardware for the mission and were part of the team operating the microscope station.

On June 2, 2005, following a critical review of the project's planning progress and preliminary design, NASA approved the mission to proceed as planned. The purpose of the review was to confirm NASA's confidence in the mission.

Specifications: Mass

350 kg (770 lb)

Dimensions About 5.5 m (18 ft) long with the solar panels deployed. The science deck by itself is about 1.5 m (4.9 ft) in diameter. From the ground to the top of the MET mast, the Lander measures about 2.2 m (7.2 ft) tall.

Communications X-band throughout the cruise phase of the mission and for its initial communication after separating from the third stage of the launch vehicle. UHF links, relayed through Mars orbiters during the entry, descent and landing phase and while operating on the surface of Mars. The UHF system on Phoenix is compatible with relay capabilities of NASA’s Mars Odyssey, Mars Reconnaissance Orbiter and with the European Space Agency’s Mars Express. The interconnections use the Proximity-1 protocol.

Power Power is generated using two gallium arsenide solar array panels (total area 3.1 m2 (33 sq ft)) mounted to the cruise stage during cruise, and via two gallium arsenide solar array panels (total area 2.9 m2 (31 sq ft)) deployed from the Lander after touchdown on the Martian surface. NiH2 battery with a capacity of 16 A·h.

Lander systems include a RAD6000 based computer system for commanding the spacecraft and handling data. Other parts of the Lander are an electrical system containing solar arrays and batteries, a guidance system to land the spacecraft, eight 1.0 lbf (4.4 N) and 5.0 lbf (22 N) monopropellant hydrazine engines built by Aero jet-Redmond Operations for the cruise phase, twelve 68.0 lbf (302 N) Aero jet monopropellant hydrazine thrusters to land the Phoenix, mechanical and structural elements, and a heater system to ensure the spacecraft does not get too cold.

Launch:

Phoenix is launched atop a Delta rocket

Noctilucent cloud created from the launch vehicle's exhaust gas.

Phoenix was launched on August 4, 2007, at 5:26:34 a.m. EDT (09:26:34 UTC) on a Delta 7925 launch vehicle from Pad 17-A of the Cape Canaveral Air Force Station.

The launch was nominal with no significant anomalies.

The Phoenix Lander was placed on a trajectory of such precision that its first trajectory course correction burn, performed on August 10, 2007 at 7:30 a.m. EDT (11:30 UTC), was only 18 m/s. The launch took place during a launch window extending from August 3, 2007 to August 24, 2007. Due to the small launch window the rescheduled launch of the Dawn mission (originally planned for July 7) had to stand down and was launched after Phoenix in September. The Delta 7925 was chosen due to its successful launch history, which includes launches of the Spirit and Opportunity Rover sin 2003 and Mars Pathfinder in 1996.

A noctilucent cloud was created by the exhaust gas from the Delta II 7925 rocket used to launch Phoenix.[26] The colors in the cloud formed from the prism-like effect of the ice particles present in the exhaust trail.

Landing

Mars Reconnaissance Orbiter (MRO) imaged Phoenix (lower left corner) in the line of sight to the 10-kmwide Heimdall Crater (the craft is actually 20 km in front of it).

MRO imaged Phoenix suspended from its parachute during descent through the Martian.

MRO image of Phoenix on Phoenix landing site near the surface of Mars. Also N. polar cap see a larger image showing the parachute / backshell,

and heat shield.

The Jet Propulsion Laboratory made adjustments to the orbits of its two active satellites around Mars, Mars Reconnaissance Orbiter and Mars Odyssey, and the European Space Agency similarly adjusted the orbit of its Mars Express spacecraft to be in the right place on May 25, 2008 to observe Phoenix as it entered the atmosphere and then landed on the surface. This information helps designers to improve future Landers. The projected landing area was an ellipse 100 km by 20 km covering terrain which has been informally named "Valley “and contains the largest concentration of water ice outside of the poles.

Phoenix entered the Martian atmosphere at nearly 21,000 km (13,000 mi) per hour, and within 7 minutes had decreased its speed to 8 kilometers per hour (5.0 mph) before touching down on the surface.

Confirmation of atmospheric entry was received at 4:46 p.m. PDT (23:46 UTC). Radio signals received at 4:53:44 p.m. PDT confirmed that Phoenix had survived its difficult descent and landed 15 minutes earlier, thus completing a 680 million km (422 million miles) flight from Earth.

For unknown reasons, the parachute was deployed about 7 seconds later than expected, leading to a landing position some 25–28 km long (east), near the edge of the predicted 99% landing ellipse. Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) camera photographed Phoenix suspended from its parachute during its descent through the Martian atmosphere. This marks the first time ever one spacecraft has photographed another in the act of landing on a planet (the Moon not being a planet, but a satellite). The same camera also imaged Phoenix on the surface with enough resolution to distinguish the Lander and its two solar cell arrays. Ground controllers used Doppler tracking data from Odyssey and Mars Reconnaissance Orbiter to determine the Lander’s precise location as 68°13′08″N 234°15′03″E / 68.218830°N 234.250778°ECoordinates: 68°13′08″N 234°15′03″E / 68.218830°N 234.250778°E. Phoenix landed in the Green Valley of Vastitas Borealis on May 25, 2008, in the late Martian northern hemisphere spring (Ls=76.73), where the Sun shone on its solar panels the whole Martian day. By the Martian northern Summer solstice (June 25, 2008), the Sun appeared at its maximum elevation of 47.0 degrees. Phoenix experienced its first sunset at the start of September 2008.

The landing was made on a flat surface, with the Lander reporting only 0.3 degrees of tilt. Just before landing, the craft used its thrusters to orient its solar panels along an east-west axis to maximize power generation. The Lander waited 15 minutes before opening its solar panels, to allow dust to settle. The first images from the Lander became available around 7:00 p.m. PDT (2008-05-26 02:00 UTC). The images show a surface strewn with pebbles and incised with small troughs into polygons about 5 m across and 10 cm high, with the expected absence of large rocks and hills.

Like the 1970s era Viking spacecraft, Phoenix used rocket motors for its final descent. Experiments conducted by Nilton Renno, mission co-investigator from the University of Michigan, and his students have investigated how much surface dust would be kicked up on landing. Researchers at Tufts University, led by coinvestigator Sam Kounaves, conducted additional indepth experiments to identify the extent of the ammonia contamination from the hydrazine propellant and its possible effects on the chemistry experiments. In 2007, a report to the American Astronomical Society by Washington State University professor Dirk Schulze-Makuch, suggested that Mars might harbor peroxide-based life forms which the Viking Landers failed to detect because of the unexpected chemistry. The hypothesis was proposed long

after any modifications to Phoenix could be made. One of the Phoenix mission investigators, NASA astrobiologist Chris McKay, stated that the report "piqued his interest" and that ways to test the hypothesis with Phoenix's instruments would be sought.

SURFACE MISSION: Communications from the surface

Approximate-color photo mosaic of cryoturbation polygons due to the Martian permafrost.

The robotic arm's first movement was delayed by one day when, on May 27, 2008, commands from Earth were not relayed to the Phoenix Lander on Mars. The commands went to NASA's Mars Reconnaissance Orbiter as planned, but the orbiter's Electra UHF radio system for relaying commands to Phoenix temporarily shut off. Without new commands, the Lander instead carried out a set of activity commands sent May 26 as a backup. On May 27 the Mars Reconnaissance Orbiter relayed images and other information from those activities back to Earth.

The robotic arm was a critical part of the Phoenix Mars mission. On May 28, scientists leading the mission sent commands to unstow its robotic arm and take more images of its landing site. The images revealed that the spacecraft landed where it had access to digging down a polygon across the trough and digging into its center.

The polygonal cracking in this area had previously been observed from orbit, and is similar to patterns seen in permafrost areas in polar and high altitude regions of Earth. A likely formation mechanism is that permafrost ice contracts when the temperature decreases, creating a polygonal pattern of cracks, which are then filled by loose soil falling in from above. When the temperature increases and the ice expands back to its former volume,

it thus cannot assume its former shape, but is forced to buckle upwards.[42] (On Earth, liquid water would probably enter at times along with soil, creating additional disruption due to ice wedging when the contents of the cracks freeze.)

The Lander's Robotic Arm touched soil on the red planet for the first time on May 31, 2008 (sol 6). It scooped dirt and started sampling the Martian soil for ice after days of testing. Phoenix's Robotic Arm Camera took an image underneath the Lander on sol 5 that shows patches of a smooth bright surface uncovered when thruster exhaust blew off overlying loose soil. It was later shown to be ice. Ray Arvidson of Washington University in St. Louis said: "We could very well be seeing rock, or we could be seeing exposed ice in the retrorocket blast zone."

Presence of shallow subsurface water ice See also: Martian polar ice caps and Water on Mars On June 19, 2008 (sol 24), NASA announced that dicesized clumps of bright material in the "Dodo-Goldilocks" trench dug by the robotic arm had vaporized over the course of four days, strongly implying that they were composed of water ice which sublimated following exposure. While dry ice also sublimates, under the conditions present it would do so at a rate much faster than observed. On July 31, 2008 (sol 65), NASA

announced that Phoenix confirmed the presence of water ice on Mars, as predicted in 2002 by the Mars Odyssey orbiter. During the initial heating cycle of a new sample, TEGA's mass spectrometer detected water vapor when the sample temperature reached 0 °C. Liquid water cannot exist on the surface of Mars with its present low atmospheric pressure, except at the lowest elevations for short periods.

With Phoenix in good working order, NASA announced operational funding through September 30, 2008 (sol 125). The science team worked to determine whether the water ice ever thaws enough to be available for life processes and if carbon-containing chemicals and other raw materials for life are present.

Additionally during 2008 and early 2009 a debate emerged within NASA over the presence of 'blobs' which appeared on photos of the vehicle's landing struts, which have been variously described as being either water droplets or 'clumps of frost'. Due to the lack of consensus within the Phoenix science project, the issue had not been raised in any NASA news conferences.

One scientist believed that the Lander’s thrusters splashed a pocket of brine from just below the Martian surface onto the landing strut during the vehicle's landing. The salts would then have absorbed water vapor from the air, which would have explained how they appeared to grow in size

during the first 44 Martian days before slowly evaporating as Mars temperature dropped.

•

The first two trenches dug by Phoenix in Martian soil.

The trench on the right, informally called "Baby Bear", is the source of the first samples delivered to the onboardTEGA and the optical microscope for analysis.

•

Die-sized clumps of bright material in the enlarged "Dodo-Goldilocks" trench vanished over the course of four days, implying that they were composed of ice which sublimated following exposure.

•

Color versions of the photos showing ice sublimation, with the lower left corner of the trench enlarged in the insets in the upper right of the images.

Wet chemistry: On June 24, 2008 (sol 29), NASA's scientists launched a major series of tests. The robotic arm scooped up more soil and delivered it to 3 different on-board analyzers: an oven that baked it and tested the emitted gases, a microscopic imager, and a wet chemistry lab. The Lander’s Robotic Arm scoop was positioned over the Wet Chemistry Lab delivery funnel on Sol 29 (the 29th Martian day after landing, i.e. June 24, 2008). The soil was transferred to the instrument on sol 30 (June 25, 2008), and Phoenix performed the first wet chemistry tests. On Sol 31 (June 26, 2008) Phoenix returned the wet chemistry test results with information on the salts in the soil, and its acidity. The wet chemistry lab was part of the suite of tools called the Microscopy, Electrochemistry and Conductivity Analyzer (MECA).

Preliminary wet chemistry lab results showed the surface soil is moderately alkaline, between pH 8 and 9. Magnesium, sodium, potassium and chloride ions were found; the overall level of salinity is modest. Chloride levels were low, and thus the bulk of the anions present were not initially identified. The pH and salinity level were viewed as benign from the standpoint of biology.

TEGA analysis of its first soil sample indicated the presence of bound water and CO2 that were released during the final (highest-temperature, 1,000°C) heating cycle.

On August 1, 2008, Aviation Week reported that "The White House has been alerted by NASA about plans to make an announcement soon on major new Phoenix Lander discoveries concerning the "potential for life" on Mars, scientists tell Aviation Week & Space Technology." This led to a subdued media speculation on whether some evidence of past or present life had been discovered. To quell the speculation, NASA released preliminary and unconfirmed findings which suggest that Mars soil contains perchlorate and thus may not be as Earth-like and life-friendly as thought earlier.

•

Phoenix footpad image, taken over 15 minutes after landing to ensure any dust stirred up had settled.

•

One of the first surface images from Phoenix.

•

View underneath Lander towards south foot pad, showing patchy exposures of a bright surface, possibly ice.

Panorama of rocks near the Phoenix Lander (May 25, 2008).

Panorama of rocks near the Phoenix Lander (August 19, 2008).

A 360-degree panorama assembled from images taken on sols 1 and 3 after landing. The upper portion has been vertically stretched by a factor of 8 to bring out details.

Visible near the horizon at full resolution are the backshell and parachute (a bright speck above the right edge of the left solar array, about 300 m distant) and the heat shield and its bounce mark (two end-to-end dark streaks above the center of the left solar array, about 150 m distant); on the horizon, left of the weather mast, is a crater.

End of the mission: The solar-powered Lander operated two months longer than its three-month prime mission. The Lander was designed to last 90 days, and had been running on bonus

time since the successful end of its primary mission in August 2008.[6] On October 28, 2008 (sol 152), the spacecraft went into safe mode due to power constraints based on the insufficient amount of sunlight reaching the Lander, as expected at this time of year. It was decided then to shut down the four heaters that keep the equipment warm, and upon bringing the spacecraft back from safe mode, commands were sent to turn off two of the heaters rather than only one as was originally planned for the first step. The heaters involved provide heat to the robotic arm, TEGA instrument and a pyrotechnic unit on the Lander that were unused since landing, so these three instruments were also shut down.

On November 10, Phoenix Mission Control reported the loss of contact with the Phoenix Lander; the last signal was received on November 2. Immediately prior, Phoenix sent its final message: "Triumph" in binary code. The demise of the craft occurred as a result of a dust storm that reduced power generation even further. While the spacecraft's work ended, the analysis of data from the instruments was in its earliest stages.

Communication attempts 2010: Though it was not designed to survive the frigid Martian winter, the spacecraft's safe mode kept the option open to reestablish communications if the Lander could have recharged its batteries during the next Martian spring.

However, its landing location is in an area that is usually part of the north polar ice cap during the Martian winter, and the Lander was seen from orbit encased in dry ice. It is estimated that, at its peak, the layer of CO2 ice in the Lander’s vicinity would total about 30 grams/cm2, which is enough to make a dense slab of dry ice at least 7 1⠄2 inches (19 cm) thick. It was considered unlikely that the spacecraft could endure this condition, as its fragile solar-cell arrays would have cracked and fallen off since they were not designed to support much weight.

Scientists attempted to make contact with Phoenix starting January 18, 2010 (sol -835), but were unsuccessful. Further attempts in February and April also failed to pick up any signal from the Lander. Project manager Barry Goldstein announced on May 24, 2010 that the project was being formally ended. Images from the Mars Reconnaissance Orbiter showed that its solar panels were apparently irretrievably damaged by freezing during the Martian winter.

Results of the mission: Landscape: Unlike some other places visited on Mars with landers (Viking and Pathfinder), nearly all the rocks near Phoenix are small. For about as far as the camera can see, the land is flat, but shaped into polygons between 2–3

meters in diameter and is bounded by troughs that are 20 cm to 50 cm deep. These shapes are due to ice in the soil expanding and contracting due to major temperature changes. The microscope showed that the soil on top of the polygons is composed of flat particles (probably a type of clay) and rounded particles. Also, unlike other places visited on Mars, the site has no ripples or dunes.

[74] Ice is present a few inches below the surface in the middle of the polygons, and along its edges, the ice is at least 8 inches deep. When the ice is exposed to the Martian atmosphere it slowly sublimates.[75] Some dust devils were observed.

Weather: Snow was observed to fall from cirrus clouds. The clouds formed at a level in the atmosphere that was around −65 °C, so the clouds would have to be composed of water-ice, rather than carbon dioxide-ice (dry ice) because, at the low pressure of the Martian atmosphere, the temperature for forming carbon dioxide ice is much lower—less than −120 °C. As a result of the mission, it is now believed that water ice (snow) would have accumulated later in the year at this location. This represents a milestone in understanding Martian weather.

Wind speeds ranged from 11 to 58 km per hour. The usual average speed was 36 km per hour. These speeds seem high, but the atmosphere of Mars is very thin—less than

1% of the Earth's—and so did not exert much force on the spacecraft. The highest temperature measured during the mission was −19.6 °C, while the coldest was −97.7 °C.

Climate cycles: Interpretation of the data transmitted from the craft was published in the journal Science. As per the peer reviewed data the presence of water ice has been confirmed and that the site had a wetter and warmer climate in the recent past. Finding calcium carbonate in the Martian soil leads scientists to believe that the site had been wet or damp in the geological past. During seasonal or longer period diurnal cycle’s water may have been present as thin films.

The tilt or obliquity of Mars changes far more than the Earth; hence times of higher humidity are probable. The data also confirms the presence of the chemical perchlorate. Perchlorate makes up a few tenths of a percent of the soil samples. Perchlorate is used as food by some bacteria on Earth. Another paper claims that the previously detected snow could lead to a buildup of water ice. The reports leaves the question of presence of organic compounds open ended since heating the samples containing perchlorate would have broken down the organic material.

Surface chemistry:

Results published in the journal Science after the mission ended reported that chloride, bicarbonate, magnesium, sodium potassium, calcium, and possibly sulfate were detected in the samples. The pH was narrowed down to 7.7 Âą0.5. Perchlorate (ClO4), a strong oxidizer at elevated temperatures, was detected. This was a significant discovery as perchlorate has the potential of being used for rocket fuel and as a source of oxygen for future colonists. Under certain conditions perchlorate can inhibit life; however some microorganisms obtain energy from the substance (by anaerobic reduction). The chemical when mixed with water can greatly lower freezing point of water, in a manner similar to how salt is applied to roads to melt ice. So, perchlorate may be allowing small amounts of liquid water to form on the surface of Mars today. Gullies, which are common in certain areas of Mars, may have formed from perchlorate melting ice and causing water to erode soil on steep slopes.

Perchlorates have also been detected at the landing site of the Curiosity rover, nearer equatorial Mars, suggesting a "global distribution of these salts".

CHAPER 7: ABOUT VIKING 2 The Viking 2 mission was part of the American Viking program to Mars, and consisted of an orbiter and a Lander essentially identical to that of the Viking 1 mission. The Viking 2 Lander operated on the surface for 1316 days, or 1281 sols, and was turned off on April 11, 1980 when its batteries failed. The orbiter worked until July 25, 1978, returning almost 16,000 images in 706 orbits around Mars.

Mission profile: The craft was launched on September 9, 1975. Following launch using a Titan/Centaur launch vehicle and a 333 day cruise to Mars, the Viking 2 Orbiter began returning global images of Mars prior to orbit insertion. The orbiter was inserted into a 1500 x 33,000 km, 24.6 h Mars orbit on August 7, 1976 and trimmed to a 27.3 h site certification orbit with a periapsis of 1499 km and an inclination of 55.2 degrees on 9 August. Imaging of candidate sites was begun and the landing site was selected based on these pictures and the images returned by the Viking 1 Orbiter.

The Lander separated from the orbiter on September 3, 1976 at 22:37:50 UT and landed at Utopia Planitia.

Normal operations called for the structure connecting the orbiter and Lander (the bioshield) to be ejected after separation, but because of problems with the separation the bioshield was left attached to the orbiter. The orbit inclination was raised to 75 degrees on 30 September 1976.

Orbiter: The orbiter primary mission ended at the beginning of solar conjunction on October 5, 1976. The extended

mission commenced on 14 December 1976 after solar conjunction. On 20 December 1976 the periapsis was lowered to 778 km and the inclination raised to 80 degrees. Operations included close approaches to Deimos in October 1977 and the periapsis was lowered to 300 km and the period changed to 24 hours on 23 October 1977. The orbiter developed a leak in its propulsion system that vented its attitude control gas. It was placed in a 302 × 33,176 km orbit and turned off on 25 July 1978 after returning almost 16,000 images in about 700–706 orbits around Mars.

Lander: The Lander and its aeroshell separated from the orbiter on 3 September 19:39:59 UT. At the time of separation, the Lander was orbiting at about 4 km/s. After separation, rockets fired to begin Lander deorbit. After a few hours, at about 300 km attitude, the Lander was reoriented for entry. The aeroshell with its ablative heat shield slowed the craft as it plunged through the atmosphere.

Landing site soil analysis: The soil resembled those produced from the weathering of basaltic lavas. The tested soil contained abundant silicon and iron, along with significant amounts of magnesium, aluminum, sulfur, calcium, and titanium.

Trace elements, strontium and yttrium, were detected. The

amount of potassium was one fifth of the average for the Earth's crust. Some chemicals in the soil contained sulfur and chlorine that were like those remaining after the evaporation of sea water. Sulfur was more concentrated in the crust on top of the soil than in the bulk soil beneath.

The sulfur may be present as sulfates of sodium, magnesium, calcium, or iron. A sulfide of iron is also possible. The Spirit Rover and the Opportunity Rover both found sulfates on Mars. The Opportunity Rover (landed in 2004 with advanced instruments) found magnesium sulfate and calcium sulfate at Meridiani Planum. Using results from the chemical measurements, mineral models suggest that the soil could be a mixture of about 80% iron-rich clay, about 10% magnesium sulfate (kieserite?), about 5% carbonate (calcite), and about 5%iron oxides (hematite, magnetite, goethite?).

These minerals are typical weathering products of mafic igneous rocks. All samples heated in the gas chromatograph-mass spectrometer (GSMS0] gave off water. However, the way the samples were handled prohibited an exact measurement of the amount of water.

But, it was around 1%. Studies with magnets aboard the Landers indicated that the soil is between 3 and 7 percent magnetic materials by weight. The magnetic chemicals could be magnetite and maghemite, which could come from the weathering of basalt rock. Subsequent experiments carried out by the Mars Spirit Rover (landed

in 2004) suggest that magnetite could explain the magnetic nature of the dust and soil on Mars.

Search for life: Viking carried a biology experiment whose purpose was to look for life. The Viking biology experiment weighed 15.5 kg (34 lb) and consisted of three subsystems: the Pyrolytic Release experiment (PR), the Labeled Release experiment (LR), and the Gas Exchange experiment (GEX). In addition, independent of the biology experiments, Viking carried a Gas Chromatograph/Mass Spectrometer (GCMS) that could measure the composition and abundance of organic compounds in the Martian soil. The results were surprising and interesting: the GCMS gave a negative result; the PR gave a negative result, the GEX gave a negative result, and the LR gave a positive result. Viking scientist Patricia Straat recently stated, "Our (LR) experiment was a definite positive response for life, but a lot of people have claimed that it was a false positive for a variety of reasons." Most scientists now believe that the data were due to inorganic chemical reactions of the soil; however, this view may be changing after the recent discovery of near-surface ice near the Viking landing zone. Some scientists still believe the results were due to living reactions. No organic chemicals were found in the soil. However, dry areas of Antarctica do not have

detectable organic compounds either, but they have organisms living in the rocks. Mars has almost no ozone layer, unlike the Earth, so UV light sterilizes the surface and produces highly reactive chemicals such as peroxides that would oxidize any organic chemicals. The Lander discovered the chemical perchlorate in the Martian soil.

Perchlorate is a strong oxidant so it may have destroyed any organic matter on the surface. Perchlorate is now considered widespread on Mars making it hard to detect any organic compounds on the Martian surface.

REFERENCE: I used the information from tv, news paper and from Wikipedia. These things help me for introducing this to you. My friends, my parents also help me a lot.