__MAIN_TEXT__

Page 1


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Our Online meetings normally take place on a Wednesday evening at 7:30 pm UK time unless otherwise stated. Meetings use the Zoom.us video conferencing application.

Wednesday 11th November Dr Lauren Corlies (Deputy Head of Education and Public Outreach, Tucson, Arizona, USA) “The Vera C Rubin Observatory” (Formerly known as the Large Synoptic Survey Telescope)

Saturday 14th November at 7:00 pm GoSpaceWatch National Astronomy Week Event. “The Clearest View”. Featuring Author Nicholas Booth celebrating the exploration of the planet Mars. Plus: Win a copy of Nicholas’ latest book “The Search for Life on Mars” Wednesday 2nd December Valerie J. Calderbank BSc, MBCS, CEng, CITP, FRAS: “Myths and Legends of the Stars” Wednesday 16th December John McLean FRAS: “The OSIRIS-REx Mission”

Wednesday 6th January Jay Tate (The Spaceguard Centre): “The Search for Near Earth Objects” Wednesday 27th January Dr David Whitehouse (former BBC Science Reporter): “Space 2069” Wednesday 3rd February Naomi Rowe-Gurney (Phd Student at the University of Leicester): “Ice Giants and the James Webb Space Telescope” Wednesday 17th February Howard L.G Parkin BSc. BEd. FRAS, Isle of Man: “Dark Skies Tourism” Wednesday 3rd March Sharad Bhaskaran (Mission Director, Astrobotic) Pittsburgh, Pennsylvania, USA): “Robotic Missions to the Moon to support NASA’s Artemis programme”

Wednesday 7th April James Blake (PhD Student at the University of Warwick): “The Sticky Issue of Space Debris” Wednesday 21st April Dr Leigh Fletcher (University of Leicester) “The European Space Agency’s proposed JUICE Mission to Jupiter’s Icy Moons”.

Page 2


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Page 3


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Page 4


COVER STORY

GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Page 5


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Image Above The Astrobotic Peregrine Lunar Lander Test Article

Page 6


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Page 7


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Destination: Venus! By Adam Hibberd Planet Earth, the third rock from the Sun, has had some form of life on it for at least three and a half billion years. Up until earlier this year, our understanding has been that Earth is unique in our Solar System in this regard (though there have been certain circumstantial indicators elsewhere as we shall find later in this article). So what is so special about Earth? Clearly Earth must have the right conditions for life and key to this idea is the notion of ‘habitability’. NASA has a definition of habitability as follows: “Habitability has been defined as the potential of an environment (past or present) to support life of any kind” 1

Page 8


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Page 9


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Panspermia is the idea that life may travel between planets onboard interplanetary or interstellar travellers such as comets, asteroids, meteoroids, dust etc, etc.

Page 10


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Page 11


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Students and teachers of the Institute of Aeronautics and Space Studies created the ROCKETRY BLIDA TEAM in 2017 of the University of SAAD DAHLEB BLIDA, the team objective was to use their skill and knowledge to design, manufacture and test high power rockets of different types and categories. The team participated in the three previous editions of the Algerian rocketry competition. The first was in 2017 with a small team of seven people where this project allowed the team to discover teamwork in depth and allowed to acquire theoretical and technical knowledge in various fields. The second participation was in 2018 with a team of 15 people. This time multidisciplinary and even more committed. In both first editions, the team won third place with the award for "Best rocket design".

Page 12


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

•Lockheed Martin to

develop UK launch operations from Shetland Space Centre on the island of Unst.

•Orbex and Highlands and

Islands Enterprise continue to advance launch plans from Space Hub Sutherland.

Page 13


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Ancient Light Steve Barrett The Universe is vast and ancient. Large telescopes such as the Hubble Space Telescope have imaged galaxies that are billions of light-years distant. It is easy to assume that any instrument that is capable of detecting the light from such distant objects must be very sophisticated and very expensive, with a price tag as astronomical as the distances involved. In this article I show that this is not so by demonstrating that an everyday camera designed to take photographs in normal daylight can be used to capture the light from a very remote object, light that has been travelling for billions of years.

In the UK the midsummer nights are almost nonexistent, with just a couple of hours of reasonable darkness squeezed in between evening and morning twilight, and so any attempts at stargazing are limited. With a certain level of boredom regarding the lockdowns that were imposed during the summer of 2020 in an attempt to control the pandemic sweeping across the world, I was looking for a 'lockdown challenge' to keep me going. When a friend said that he had used his large telescope in his back-garden observatory to obtain an image of a very remote galaxy, it got me thinking... Is it possible to capture an image of one of these very remote objects without using a telescope? With my interest well and truly sparked, there followed a few frustrating weeks of cloudy nights. I used the time to do some homework on the most remote object that I thought I had a chance of photographing with my camera. In 2019 professional astronomers published a survey of bright quasars[1]. A quasar is the nucleus of a galaxy that emits enough light to be seen at a distance of billions of light-years. The only object that can provide this amount of energy is a supermassive black hole (SMBH) and it is thought that a SMBH exists at the centre of many, if not all, large galaxies. This includes our own Milky Way galaxy, but the difference between a quasar and our Milky Way is that in a quasar there is a large amount of material falling into the SMBH, releasing huge amounts of energy in the form of electromagnetic radiation from x-rays to radio waves. (In our Milky Way the SMBH at its centre has apparently stopped 'feeding' on the surrounding material and is quiescent.) One of the quasars reported in this survey fitted the criteria for my 'lockdown challenge' – it is high in the sky as observed from the UK during the summer months; it is bright enough for me to stand a chance of photographing it; it is very remote at a distance of many billions of light-years (more about how distances are calculated later). Having identified the target quasar[2] the first opportunity to try to image it came on the night of

20/21 July. My camera equipment comprises a Nikon D7500 digital SLR camera with a 300 mm f/4 telephoto lens. This is the camera and lens that I use for wildlife photography[3] – they are not 'special' or 'customised' or 'modified' in any way for astrophotography. I set up the camera on a small star tracker that rotates the camera at 1 revolution/day to follow the stars, as shown in Figure 1. A star tracker can be built as a DIY project [4] or they are available commercially from various manufacturers, including wind-up clockwork and motorised versions. The quasar's location in the sky, given by its celestial coordinates[2], is in the constellation of Draco (Figure 2) which is high in the sky during the darkest part of the night in the spring/summer. Because of its distance, the apparent brightness of the quasar is very dim compared to the (much closer) stars that can be seen with the naked eye. The brightest stars in the sky are about magnitude 0, the faintest stars visible in dark skies are about magnitude 5 or 6, and so at magnitude 17 the quasar is some 50,000 times dimmer than the faintest naked-eye stars. To photograph such a faint object a long exposure is required, and hence the need for a star tracker to avoid the stars and the quasar trailing across the image as the Earth turns during the exposure. Not knowing exactly how long was necessary, I exposed for as long as the short summer night allowed. Rather than take a single very long exposure, I took a continuous series of shorter 30-second exposures over a period of about an hour either side of midnight. The advantages of this approach to astrophotography are two-fold: (i) the precision with which the tracker has to move the camera to keep the stars sharp pinpoints is much less demanding, as it only needs to keep the camera pointing in exactly the right direction for a minute or so, not the full two hours of exposure; and (ii) if any images are spoiled by passing clouds then they can be thrown away before all the 'good' exposures are added together by computer software to produce an image comparable to taking a single two-hour-long exposure. (This technique would have been totally impracticable Page 14

Fig. 1 Above: Nikon camera and lens on an iOptron SkyTracker (white box). The tracker rotates the camera at 1 rev/day and so, providing that the tracker is aligned parallel to the Earth's axis using the small polar alignment scope, the camera will follow the stars.

Fig. 2 Above: The constellations of Draco and Ursa Minor, showing the rectangular field of view of the 300 mm lens. The small dot in the centre of the rectangle is a fifth-magnitude star that is conveniently close to the quasar (which is much fainter than the star) making it easier to ensure that the camera is pointing in the right direction.


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Fig 4 Above: Zooming in still further shows that most of the light from the quasar is focussed into just one pixel of the 20 megapixel image.

Fig. 3 Above: The full field of view of the 300 mm lens with an inset showing a zoom in to the central region – the quasar is indicated by the two red lines.

using photographic film, but with digital images it is straightforward to take dozens or hundreds of exposures and add them together using software that ensures that all the the stars are in the same position in each image, thus eliminating any signs of the stars trailing.) The final image, the result of adding together 256 exposures of 30 seconds each, is shown in Figure 3. The inset shows a zoom in to the central region of the image, adjacent to the fifth-magnitude star that made it easier to point the camera in the right direction. The quasar is in the centre of the inset, indicated by the two red lines. Zooming in still further (Figure 4) shows that most of the light from the quasar is focussed into just one pixel of the full 20 megapixel image. This demonstrates that an ordinary camera can capture light from an object that is so remote that the light that forms the image has taken billions of years to reach us. Figure 5 shows that the small section of the full image, covering about 0.1° x 0.1° of sky, has captured 10 galaxies in addition to the quasar itself. These galaxies cannot be distinguished by eye as most of them are so distant that they look very similar to the (much closer) stars in our Milky Way galaxy – identifying these objects as galaxies can only be achieved by comparing the image with archive images of the same patch of sky taken by professional research telescopes. If the number of galaxies found in this small section is typical of the whole image, covering 4.5° x 3° of sky, then it may have captured as many as 7000 galaxies in total. It is sobering to realise that this is comparable to the number of galaxies captured by the Hubble Space Telescope in the iconic Hubble Deep Field images.

Fig. 5: This small section of the full image covers about 0.1° x 0.1° of sky and has captured 10 galaxies (circled) in addition to the quasar itself.

Having shown that it is possible to capture the light from this quasar using a digital SLR camera, the big question is ... just how far away is it? If the quasar is just a tiny dot, even in a large telescope, how can its distance be determined? The distance to the quasar cannot be measured. The length of time that the light has been travelling to reach us also cannot be measured. The key to determining distances on cosmological scales is the one thing Page 15

that can be measured – the spectrum of the light formed by measuring the light intensity as a function of its wavelength (or colour). The spectrum of light emitted by an object that is moving relative to us will exhibit features (peaks or troughs in the light intensity) that do not appear at the same wavelengths as they would if the light source was not moving relative to us. Objects moving away from us have their spectral features shifted to longer (redder) wavelengths and so this is called a redshift. The redshift is quantified by dividing the shift in wavelength by the wavelength expected for a stationary light source, and the resultant number is given the symbol z. Figure 6 shows the visible spectrum for the quasar, from wavelengths of 4000Å (blue) to 7000Å (red). The largest feature in the spectrum has been identified as being redshifted from about 1200Å, in the ultraviolet part of the spectrum, to 6500Å due to the high recession speed of the quasar. The shift (6500Å – 1200Å) divided by unshifted value (1200Å) is equal to 4.3, so this quasar has a redshift of z = 4.3. Determining the distance to the quasar is complicated by the fact that the Universe is continuously expanding, and so the distance between any two objects keeps changing. Not only that, but the rates at which the distances increase with time also change with time. This means that we can only calculate the distance to a remote object if we have some understanding of how the Universe is expanding, and in particular how the Universe has expanded over the time interval between the time when the light left the object (perhaps billions of years ago) up to the time when it arrived here on Earth (now). The so-called concordance model of the Universe is based on the currently accepted 'best guess' of the parameters that determine the way that the Universe expands and evolves[5]. Using these parameters it is possible to convert measurements of redshift into distances and these are shown in Figure 7 (overleaf) for redshift values between z = 0 and z = 6. For every value of redshift, three distances can be calculated: (i) the distance to the


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020 Fig. 6 Left: The spectrum of the quasar from wavelengths of 4000Å (blue) to 7000Å (red). The large peak has been redshifted from 1200Å, beyond the left end of this spectrum, to 6500Å as a result of the quasar receding from us at a speed greater than the speed of light. Figure adapted from Reference [1].

object when the light was emitted (blue line); (ii) the distance that the light has travelled to reach us (green line); and (iii) the distance to the object now (red line). For small values of the redshift these three distances are essentially the same, but for larger redshifts they differ substantially because the Universe expands by a significant amount in the time it takes the light to travel from the object to us. Taking the distances calculated for our quasar with a redshift of z = 4.3 we find that the quasar was about 5 billion light-years away when the light was emitted; the light from the quasar has been travelling for over 12 billion years; while the light was travelling the Universe continued to expand and so the quasar is now about 25 billion lightyears away. The light-travel time, also known as the look-back time, of over 12 billion years is absolutely mindboggling. Bearing in mind that no telescope, no matter how powerful, can look back further than 13.8 billion years (the age of the Universe) it is remarkable to realise that a camera can 'see' light

that has been travelling for 90% of the age of the Universe. A quick back-of-the-envelope calculation using the distances quoted above leads to a very interesting conclusion. The distance to the quasar increased by 20 billion light-years during the light-travel time of 12 billion years, so that corresponds to the quasar receding from us at a speed that is greater than the speed of light. At first sight this seems wrong, but actually this does not contradict any laws of physics. The quasar is not moving through space at this speed, but the Universe is expanding at this rate and the quasar is 'along for the ride'. A more detailed calculation tells us that when the light was emitted, the quasar was receding from us at a little more than twice the speed of light. When looking at the image of the quasar, I like to think about the incredible journey that the ancient light has taken to form the image, with the narrative as seen from the perspective of the light…

it is remarkable to realise that a camera can 'see' light that has been travelling for 90% of the age of the Universe

Fig. 7 Left: Converting redshift to distance depends on models of how we think the Universe has expanded over the billions of years that the light has taken to reach us. The distance to the object when the light was emitted (blue), the distance that the light has travelled to reach us (green) and the distance to the object now (red) are shown as a function of redshift z. The values are given for the quasar at z = 4.3.

Page 16


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

• The light was emitted by the quasar 1.4 billion years after the Universe was born in the Big Bang.

• For the first 2 billion years of its journey, the light was dragged backwards by the Universe expanding at a rate that was greater than the speed of light. Throughout this time, the light made no headway towards us. Eventually, it started to close the distance to us.

• It had already been travelling for nearly 8 billion years when the Sun Dr Steve Barrett is a Senior Research Fellow in the Department of Physics at the University of Liverpool. His research interests have centred around the applications of imaging and spectroscopy to fields such as nanoscience, geomaterials, biomedical imaging and infrared spectroscopy. His teaching to undergraduate students has covered many topics and included supervision of astrophysics students on astronomy field trips to the Teide Observatory in Tenerife. He is an expert in image processing and image analysis and has written image analysis software that has been used by researchers throughout the world.

and the Earth were born. It continued on its journey through the void for another 4.5 billion years.

• Life evolved on Earth. The light travelled on. • Dinosaurs came and went. The light travelled on.

• In the last million years of its journey it arrived at the edge of our Milky Way galaxy, crossed a few spiral arms, and entered the Solar System.

• In its last few hours it finally arrived at Earth, travelled through the atmosphere in a fraction of a second, hurtled towards England, dodged a few clouds, entered the lens and hit the camera sensor. Just a pixel in the image, but what a journey!

References

His interest in astronomy and spaceflight predates his professional career as a physicist. He has given hundreds of astronomy-related talks to astronomical societies, special interest groups and schools to an audience totalling over 10,000 people. As a result of giving these outreach talks he was awarded the Sir Patrick Moore Prize in 2019 by the British Astronomical Association. Combining his research interests in imaging with his love of astronomy, it is no surprise that he has found astrophotography a very rewarding hobby. University website link: https://www.liv.ac.uk/~sdb

Page 17


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Page 18


GoSpaceWatch Limited — CAPCOM Magazine: Volume 31 Number 2 — November 2020

Page 19


GoSpaceWatch Limited 58 Park Road, Wollaston, STOURBRIDGE. DY8 3QX. 07821 896 304.

Copy Deadline All contributions intended for the January 2021 issue should be emailed to capcom@gospacewatch.co.uk by

Friday 18 December 2020

Profile for gospacewatch

GoSpaceWatch CAPCOM Magazine - November 2020  

Welcome to GoSpaeWatch CAPCOM Magazine Volume 31 Number 2. In this issue Adam Hibberd looks at a Mission to Venus, Steve Barrett photographs...

GoSpaceWatch CAPCOM Magazine - November 2020  

Welcome to GoSpaeWatch CAPCOM Magazine Volume 31 Number 2. In this issue Adam Hibberd looks at a Mission to Venus, Steve Barrett photographs...

Advertisement