Astronomy News

"American Icon" Jacket that flew to the Moon sold for record price at auction

Maurane Gisiger — Thu, 28 Jul 2022 08:58:32 +0000

"American Icon" Jacket that flew to the Moon sold for record price at auction

Maurane Gisiger Thu, 07/28/2022 - 08:58

"After deep consideration, the time felt right to share these items with the world, which for many are symbols of a historical moment, but for me have always remained personal mementos of a life dedicated to science and exploration. I hope that this collection offers some insight into what it has been like to be Buzz Aldrin."

Buzz Aldrin wearing the Inflight Coverall Jacket in 1969

At 92, Buzz Aldrin is the last living member of the 1969 Apollo 11 crew, which was the first to land on the Moon, making him the second man to ever walk on a celestial body other than our Earth. He recently gave up 69 of his personal items, including numerous flight plans and data cards, but also and uniquely, his Inflight Coverall Jacket, to be sold at an auction. Sotheby's, the organiser, titled the sale "Buzz Aldrin: American Icon” and on the 26^th of July, the race to make the highest offer began, to exceed all expectations.

The Jacket presented for auction

The highest bidder had to fork out $ 2’772’500 for this exceptional object from the history of space exploration. Not only is this the highest price ever paid for any American space-flown artifact sold at an auction, but Aldrin’s jacket is also the only piece of clothing from Apollo 11 to have ever been sold for private ownership.

Mare Tranquilitatis, where Apollo 11 landed, also harbours fascinating geological features like this pit

Jackets, though, won’t by themselves be enough to keep astronauts alive on the Moon for extended periods of time. But this week, the Lunar Reconnaissance Orbiter (LRO) may just have found safe spots for a lunar base. Astronomers have been aware of the presence of lunar pits since 2009, and then their potential to shield human explorers from solar radiation, cosmic rays and micrometeorites had already been recognised.

The Marius Hills pit imaged three times by the LRO, each time with different lighting

What’s new are the LRO’s measurements of these pits’ temperature. Because the Moon is tidally locked to the Earth, a “day” on the Moon lasts about 2 weeks (half a lunar phase cycle), so that the temperature can climb up to 127° C before falling down to -173° C at “night”. In these pits however, the temperature remains quite stable at a comfortable 17° C.

Pit at Mare Ingenii (Sea of Cleverness), with temperature taken at "night" by the Diviner Lunar Radiometer Experiment, showing a warmer central pixel

Moreover, the pits are most likely to have formed when lava tubes collapsed – molten lava flowed underneath a solidified crust, eventually forming a hollow tube, the ceiling of which collapsed. This opens up the possibility that there might be “caves” that the pit leads into – the remainders of the aforementioned tubes. These caves would likewise be protected against extreme temperature variations, which makes them targets of choice for space agencies, of which multiple have indicated interest in constructing a Moon base sooner rather than later.

A computed high-resolution elevation map of a crater - the new method allows to characterise changes in the lunar topography much more efficiently than from orbiter images like LRO's.

The promising avenue that these caves constitute, are all the more exciting considering recent developments in our capability to map the surface of the Moon: a PhD candidate at the University of Copenhagen has been working on an algorithm which determines a rocky body’s topography from shadows seen in images of its surface. An orbiter like the LRO can reach a resolution of about 300 feet, but knowing about the presence and shape of small features is vital too, whether for rover operation or landing of manned missions. By inputting details about rock formation, such precise details can be calculated with the student’s new tool. More applications that she is thinking about notably include assessing the shape of little rocks on Mars (as imaged by rovers) in order to find former presence of water.

As the Apollo 11 mission continues to make history, astronomers persist to study our celestial companion for a potential return.

Cover Image: Apollo 11 crew, AP Photo
Image Credits:
1 - Aldrin, NASA
2 & 3 - The Jacket for auction, Sotheby's
4 - Mare Tranquilitatis pit, NASA/GSFC/Arizona State University
5 - Marius Hills taken by LRO, NASA/GSFC/Arizona State University
6 - Fig. 1b from Horvath et al., 2022
7 - Fig 12 from Fernandes et al., 2022

From Stargazing to MoleGazer

Maurane Gisiger — Wed, 20 Jul 2022 22:46:07 +0000

From Stargazing to MoleGazer

Maurane Gisiger Wed, 07/20/2022 - 22:46

On the 14th July, at the 2022 Royal Astronomical Society-hosted National Astronomy Meeting, Dr Morrell presented a revolutionary tool to diagnose skin cancer. Yes, it has something to do with astronomy!
An interdisciplinary team of astrophysicists and medical doctors are applying an Artificial Intelligence (AI) technology that has been used to observe our night sky to full-body scans of patients presenting potentially risky moles.

The initial software, i.e., the one for astronomy, was designed to detect supernovae. In 2014, Prof Sullivan’s group was awarded funding to understand the physics of Type Ia supernovae better, notably in order to track the evolution of dark energy over the course of the history of the Universe. Dark energy is the phenomenon of the accelerated expansion of the Universe, and it is interesting to consider what variations in this expansion have been in the past – for instance, did dark energy accelerate the expansion more slowly at some point in the past before becoming the rather fast acceleration we observe today (remember that acceleration is not speed, e.g., imagine accelerating from 0 to 100 in a tractor vs. in a race car, both are accelerating but at different rates) ? Or more generally, is there any pattern that could tell us something about the nature of dark energy? In very broad terms, measuring the rate of the expansion of the Universe at different redshifts (“ages of the Universe) can be done by considering Type Ia supernovae because they are standard candles, as illustrated below.

The formation process for Type Ia supernovae: since it is always the same, the evolution of the brightness will always be the same too. Thus it is possible to obtain their distance, and doing so at different redshifts allows astronomers to understand the expansion history of the Universe.

A big part of the project was to develop an algorithm, using datasets from the Public ESO Spectroscopic Survey of Transient Objects (PESSTO). A whole map of the sky is created as thousands of images are taken by PESSTO’s instruments, every night. Over time, the AI from Prof Sullivan’s group may notice changes in the brightness of certain stars. These are tracked and reported if they fit the pattern of a Type Ia supernova, which is standardly that three weeks after explosion, they reach peak brightness before gradually fainting.

From Astronomy to Medicine

Back to our dermatologists: the supernova AI was modified to consider a patient’s skin as the sky background and moles as stars. As before, the targets are monitored over time. In this analogy, the “supernova” would be any significant change in the appearance of the mole, which could indicate that it developed into melanoma (skin cancer). Traditionally, the diagnosis is time-consuming as a trained dermatologist has to visually inspect every mole on a full-body photograph of a high-risk patient’s body. What’s more, the changes can be very subtle. Instead, MoleGazer is trained on datasets that show these evolutionary pathways of benign moles into melanoma. The hope is that eventually, it can be used as a diagnostic tool, to alert the doctors early on and allowing rapid treatment. The clinical study should be completed in late 2024.

MoleGazer highlighting potentially risky moles

It’s worth noting that skin cancer is one of the most common cancers, with over 150 000 cases per year in the UK alone. As Dr Morell says, “finding ways we can use astronomers’ tools elsewhere is important and a great example of collaboration between scientific disciplines."

Cover Image: Moles and moles as star-like targets, The MoleGazer Team
Image Credits:
1 - Progenitor of SNe Type Ia, ESA and A. Feild (STScI)
2 - Medical application, University of Southampton
3 - MoleGazer at work, University of Southampton

“A ground-breaking new view of the cosmos”

Maurane Gisiger — Wed, 13 Jul 2022 15:14:08 +0000

“A ground-breaking new view of the cosmos”

Maurane Gisiger Wed, 07/13/2022 - 15:14

Not just one, not two, but five carefully selected full-colour images reveal the full power of the JWST for the first time !

You will have seen it all over the news: on Tuesday 12^th July, NASA Administrator Bill Nelson and US president Joe Biden presented the JWST’s first science images to the public. Let’s take an astrophotographer’s perspective on this!

The Carina Nebula, a star-forming region
The Southern Ring Nebula, a planetary nebula

Two of those images were of nebular targets, the Carina Nebula and the Southern Ring Nebula. In the first case, thanks to its infrared “eyes” the JWST allows astronomers to look into the star-forming region, and actually spot some young stars still clothed in dust.

Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) combined image

On the other hand, the Southern Ring is a planetary nebula, i.e., the leftovers from the death of a low-mass star. Besides the white dwarf which remains, too, this particular system also hosts a second star, which the Mid-Infrared Instrument (MIRI) captured for the first time.

HST view of the Southern Ring

To really wrap your mind about how unbelievably great the JWST’s resolution is, NASA provides images from the Hubble Space Telescope images as a helpful comparison point. On NASA’s website, you can also zoom into these incredible views of our cosmos even further.

Stephan's Quintet

Besides looking at objects of great interest for stellar astrophysicists, the JWST captured not just one, not two, but again, a quintet, this time of galaxies. Known as Stephan’s Quintet (or formally the Hickson Compact Group 92), you may know this group of galaxies from the film “It’s a Wonderful Life”. The JWST picture above is actually a mosaic, combining almost 1000 images into one gigantic frame that looks at an area of the sky that’s roughly a fifth of the Moon’s diameter. There are many galaxies besides those of HCG 92 in this frame that form a stunning background canvas.

Details of the AGN were taken with the Near-Infrared Spectrograph (NIRSpec).
"The instrument’s integral field units (IFUs) – a combination of a camera and spectrograph – provided the Webb team with a “data cube,” or collection of images of the AGN's spectral features. Much like medical magnetic resonance imaging (MRI), the IFUs allow scientists to “slice and dice” the information into many images for detailed study. NIRSpec’s IFUs measured the bright emission from outflows of hot gas near the active black hole and it was able to determine its composition."

Although called a quintet, HCG 92 is actually composed of four galaxy which are interacting plus the leftmost one – as you can see, thee JWST was able to resolve individual stars in it because of its proximity to us. Interestingly, the topmost galaxy NGC 7319 contains an Active Galactic Nucleus, which is very promising for research into supermassive black holes and their growth.

Atmospheric composition of WASP-96b

If that sounds exciting (and it is!), there is even more! Let’s not forget the JWST’s capabilities in terms of observing exoplanets. The fourth image is actually a spectrum of an exoplanetary atmosphere, taken during the transit of WASP-96 b across its host star.

It is quite a curious planet: its diameter is 1.2 times that of Jupiter, yet its mass is less than half that of Jupiter and it is much closer to its star than even Mercury is to our Sun (a year there only lasts 3.5 days), and researchers believe that the temperature can reach more than 1000 °. What the JWST discovered, on top of confirming these other properties, is the presence of clouds and water in this giant exoplanet’s atmosphere.

The Near-Infrared Spectrograph (NIRSpec) can gather spectra of up to 150 individual objects simultaneously.
Gravitational lensing: galaxy cluster SMACS 0723 distorted, magnified, and mirrored many galaxies in this field

For cosmologists and, in fact, the majority of people, the most impressive image remains Webb’s First Deep Field (FDF) – and of course, it made it to be the cover image for this article. Beyond being stunning in and of itself, the FDF’s beauty lies in it being “the deepest and sharpest infrared image of the distant universe”; the improvement on Hubble’s Ultra Deep Field can be seen below.

JWST's FDF (MIRI and NIRCam Images Side by Side)
HST's UDF

Hubble took weeks to obtain its UDF. Webb’s FDF only took 12.5 hours of exposure.

It’s almost mentioned as a side result that this image of galaxy cluster SMACS 0723 includes some of the faintest objects that have ever been observed in the infrared. Oh, and the Near Infrared Spectrograph (NIRSpec) measured 48 individual galaxies at the same time. Notably to determine that one of the galaxies is at a distance of 13.1 light-years.

All of this is seriously mind-blowing.

All Image Credits to: NASA, ESA, CSA, STScI

The birth of quasars finally decoded

Maurane Gisiger — Thu, 07 Jul 2022 06:52:53 +0000

The birth of quasars finally decoded

Maurane Gisiger Thu, 07/07/2022 - 06:52

For decades, astronomers had been scratching their heads about this mystery: how could objects with masses of thousands of solar masses at birth form so early in the cosmic timeline?

The first of these “Quasi-Stellar Radio Sources” was discovered in the sixties, and by the eighties it was understood that quasars are galaxies hosting supermassive black holes which accrete gas and releases enormous amounts of energy, making quasars the most luminous objects “out there”. The most mind-bending fact though, is that 200 of them had already formed by the time our Universe was celebrating its first billionth anniversary. Until now, astronomers thought only very fine-tuned and somewhat exotic environments, e.g., with a strong ultraviolet radiation background, could be suitable for the formation of these giants.

Structure of a quasar

A team from the University of Portsmouth developed supercomputer models to demonstrate that actually, quasars form naturally from turbulent clouds of gas. In their scenario, cold streams of gas prevent the cloud from collapsing too early, enabling the formation of stars at unimaginable scales – 30 000 solar masses or so. These supermassive stars will burn through their fuel extremely quickly, about 250 000 years, before collapsing to sizeable black holes. So, primordial halos of gas “conveniently created the massive seeds” of quasars, as the lead author of the study puts it.

Supercomputer simulation of the birth of a primordial quasar

"Turbulence prevents the formation of any coherent structures in the halo, such as the large accretion disks that form during the collapse of atomically cooled haloes. The core of the halo instead develops a wispy, filamentary structure that is interspersed with dense clumps."
C1 and C2 are supermassive stars that will collapse into black holes that are viable seeds for forming quasars

Speaking of really old galaxies, MACS1149-JD1 made the headlines again, too. Despite it being one of the farthest known galaxies, astronomers were able, using ALMA, to measure redshift from position to position inside the galaxy. This was done in order to establish that this is the earliest source yet found that has a rotating disk of gas and stars. It’s a slow rotation (50 km/s compared to 220 km/s for our Milky Way), suggesting that is has only just started rotating – a unique find. In the standard picture of galactic evolution, older stars are found at the centre while star formation continues in the rotating disc. The researchers hope that identifying the precise positions of stars of different ages in MACS1149-JD1 will help establish this theory.

MACS1149-JD1: the earliest galaxy with rotation

Another fossil from the early Universe was found in our neighbour’s backyard, and by an amateur astronomer! By looking through archival data taken with the Dark Energy Camera on the Blanco Telescope at the Cerro Tololo Inter-American Observatory (CTIO), G. Donatiello noticed a “smudge”. After follow-up observations with the Gemini North telescope, it turns out that this feature is Pegasus V, a very old, metal-deficient faint galaxy around the Andromeda galaxy. While it is a difficult task to spot such faint galaxies, astronomers are very keen to discover them because if the observed numbers are inconsistent with predictions, they might have to review their assumptions about dark matter. On top of that, studying the chemical properties of objects like Pegasus V can provide clues into the time of the formation of the first stars.

Pegasus V: a fossil from the Early Universe

The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) will be essential for astronomers to build up their hypotheses about galaxy formation and evolution, notably in this last quest for faint galaxies – excitingly, the LSST’s first light is scheduled for 2023. But even sooner, there’s of course the JWST: its first full-colour image is due to be delivered by NASA next Tuesday, as the telescope is getting ready to give the most detailed ever infrared observations of galaxies in the early Universe.

Cover Image: Stills from the simulation, Latif et al., 2022
Image Credits:
1 - Structure of quasar, NOIRLab/ NSF/ AURA/ J. da Silva/ Keck Observatory
2 - Video: simulation of the birth of a primordial quasar, University of Portsmouth
3 - Fig. 4 from Latif et al., 2022
4 - MACS1149-JD1, ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, W. Zheng (JHU), M. Postman (STScI), the CLASH Team, Hashimoto et al.
5 - Pegasus V, International Gemini Observatory/NOIRLab/NSF/AURA Acknowledgment - Image processing: T.A. Rector/M. Zamani/D. de Martin

Liquid mirror telescope sees first light in India

Maurane Gisiger — Thu, 30 Jun 2022 07:20:17 +0000

Liquid mirror telescope sees first light in India

Maurane Gisiger Thu, 06/30/2022 - 07:20

Yes, liquid mirror telescopes are a thing !

To prove that, here is the ILMT's first light ! The NGC 4274 Galaxy can be seen in the top right corner

The idea of a telescope using a liquid as a mirror is not new – the concept was already proposed by Sir Isaac Newton, who mathematically demonstrated that since the surface of a liquid rotating at a constant speed naturally takes on a nearly perfectly smooth parabolic shape, it could be used to reflect light just like a mirror. The vision has now come true with the International Liquid Mirror Telescope (ILMT), a 2 million dollar, 4 metre spinning “bowl” of 50 litres of liquid mercury. It is found at the Devasthal Observatory in the Indian Himalayas, for which the same Belgian company that built the ILMT assembled the Devasthal Optical Telescope (DOT), which has the same mirror size but cost 18 million USD. The amount is drastically reduced for the ILMT since there is no need to cast, polish and coat a mirror.

The Devasthal Observatory, with the ILMT, DOT and a smaller 1.3m scope
ILMT, view from above. A thin mylar film protects the mercury from wind and impurities

The drawback is that the ILMT is a zenith telescope, i.e., it only ever points to the zenith and can't be inclined. However, this becomes particularly useful to conduct transient surveys, where night after night the telescope “checks” the same area of the sky in search of "something new" (a transient astronomical event). This will indeed be the goal of the ILMT, with its optical twin DOT being able to rapidly carry out follow-up observations. A real problem is the toxicity of mercury, a hazard which has to be dealt with since this element is the best compromise between cost and reflectivity. Another disadvantage is the Earth’s Coriolis effect: our planet’s rotation would affect the motion of the mercury in “bowls” larger than about 8 metres.

Force diagram: gravity (red), buoyancy (green), centripetal force (blue) act on the atoms of mercury to keep it in circular motion to form a mirror-type surface

Historically, there have been some noteworthy attempts to create Liquid mirror telescopes for astronomy. Following a paper by Borra in 1982, the Universities of British Columbia (UBC) and Laval set out to build their 1.5m prototype quickly followed by a 3m one. The collaborators then moved on to build an operational one for the NASA Orbital Debris Observatory, where, as the name of the facility suggests, it was used to catalogue space debris, from 1994 to 2001. Parts of this telescope were then used to build the 6m Large Zenith Telescope (LZT), mostly used for supernova searches. The LZT was, until its decommissioning in 2016, the 3^rd largest telescope in Northern America, and with a mirror that cost just 1% of traditional mirrors of that size. UBC has been heavily involved with the ILMT, and even thinks forward to an 8m liquid telescope, baptised the Advanced Liquid-Mirror Probe (ALPACA) as well as to the Large Aperture Mirror Array (LAMA) of 66 6-meter telescopes. This would give the LAMA network a total resolving power equivalent to that of a 70m telescope, almost twice the size of the Extremely Large Telescope still under construction !

UBC/Laval LMT
LMT at NODO
LZT

The early attempts at making a liquid mirror telescope

Thinking ever larger to improve resolution, in 2020, a team at the University of Texas at Austin proposed to build a 100-meter liquid telescope on the Moon, the Ultimately Large Telescope (ULT). On top of the fact that liquid is much easier to transport than a giant lens or mirror, the ULT would be situated at one of the poles of our natural satellite, so that it would be continually observing the same patch of sky. The main advantage, though, is that the ULT’s power would not be constrained by the presence of an atmosphere – the light from distant sources is redshifted, appearing at wavelengths blocked by Earth’s atmosphere. The UT-Austin team’s hope for such an instrument is to observe an even younger Universe compared to what the JWST will soon see; in fact, their calculations show it would be possible to observe Population III stars, the ones which are believed to have formed before the first galaxies, over 13 billion years ago. These stars are theorised to have been extremely large, and hence very short-lived, but would have played a key role in enriching the Universe in elements heavier than Helium.

ULT
A space liquid mirror telescope

Artist's impressions

While establishing a program of “sustainable lunar exploration” is indeed part of NASA’s Artemis mission goals, the space agency’s efforts with regards to liquid telescopes are currently focused on the Fluidic Telescope Experiment (FLUTE) project. The principal investigator describes it simply as “in microgravity, liquids take on shapes that are useful for making lenses and mirrors”, which would enable telescopes even larger than the ULT to be built thanks to the properties of fluids – but this time, in the vacuum of space, without gravity. After successful ground tests, FLUTE moved on to experiments on board the International Space Station in April this year.

Space is the limit when it comes to building the best tools to observe our Universe !

Cover Image: ILMT, A. & J. Surdej
Image Credits:
1 - First light, ARIES
2 - Devasthal Observatory, ARIES
3 - ILMT, ARIES
4 - Force diagram, Cleonis for Wikimedia Commons
5 - UBC/Laval 2.7m LMT, UBC
6 - LMT at NODO, NASA
7 - LZT, NASA
8 - ULT, Steward Observatory/University of Arizona
9 - FLUTE could be used to build such a giant liquid telescope, Studio E. Maru

A great month for planets

Maurane Gisiger — Thu, 23 Jun 2022 06:45:54 +0000

A great month for planets

Maurane Gisiger Thu, 06/23/2022 - 06:45

This month, all the planets of our Solar System are visible !

And on Friday the 24^th, they are visible in just one go, early in the morning. Beautifully, the 5 naked-eye planets (Mercury, Venus, Mars, Jupiter and Saturn) will then be lined up in order of their distance from the Sun – with the Moon, too, finding its place between Venus and Mars. Uranus and Neptune are visible in the positions indicated in the cover image, and are visible with binoculars or a small scope. Mercury may be the hardest one to spot as it will rise above the Eastern horizon shortly before sunrise.

Another perspective on the alignment: top-down view

This wonderful planetary coincidence is not to be missed, as it is only possible to see such a sequential arrangement of the naked eye planets every 18 years – let alone with a crescent Moon in the right place and the possibility of seeing our solar system’s ice giants. Note that the peculiar arc formed by the planets is equivalent to the ecliptic, the plane of all the planets’ orbits around the Sun.

17/06 over White Bear Lake, Minnesota
20/06 over New York
21/06 over Taipei

The progression of the alignment - with an amazing opportunity this Friday where even the Moon is "in the right place" between Venus and Mars

Not only do our neighbouring planets offer this stunning sight, we are also constantly learning more about them. The many probes around or on Mars, for instance, keep sending in new data. Three instruments on board the Mars Reconnaissance Orbiter have been used conjointly to find a region with clay sediments, suggesting that water would have flown in that Ladon basin region until “recently” – 2.5 billion years ago – which is indeed much more recent than previously thought. The MARSIS instrument of ESA’s Mars Express mission, on the other hand, is looking for water underneath the surface of Mars, and has just been given a well-deserved software update to perform its task after 19 years of operating on Microsoft Windows 98.

"presence of clays support an environment that would have been favorable to life at that time"

You, too, can get involved with state-of-the-art research in planetary science, with a new project on Zooniverse: Jovian Vortex Hunter. The team of researchers at the University of Minnesota are asking citizen scientists to catalogue features in images of Jupiter taken by NASA’s Juno spacecraft. More precisely, participants have to identify atmospheric vortices, storms that come in various sizes and shapes – this will help the researchers understand the physics behind Jupiter’s weather. Guides and video tutorials are provided, and the aim is to have at least 16 people examining every image. For now, there are under 500 volunteers for a whooping 60 000 images, so why not head over to Zooniverse (once you’re done reading this article!) and measure a couple of vortices ?

A region close to Jupiter's north pole. There is a huge diversity in the colors and shapes of vortices

As we are considering the gas giants, let’s not forget about their incredible moon systems. Jupiter’s moon Europa has finally been observed at Ultraviolet wavelengths, revealing sulphur dioxide on the trailing hemisphere of Europa. The most likely explanation for the presence of this molecule is that volcanoes on Io, another Jovian moon, release sulphur, which then gets transported to Europa through Jupiter’s magnetic field where it interacts with water ice to become sulphur dioxide. Astronomers believe that there is an ocean below Europa’s surface, and while the surface does look like water ice in visible wavelength, more studies need to be conducted in the UV band where this moon looks so different - potentially exposing the presence of even more compounds.

Io (bottom) and Europa (top)
Map of SO2 on Europa

Saturn’s moons are not to be left out: in a recent study by the Southwest Research Institute, elliptical craters (which are much less common than circular ones) on Tethys and Dione were surveyed. Considering patterns in the data, especially the direction in which these craters point, it may be possible to determine the ages of these moons. This new perspective on cratering is especially exciting for the instigator who hopes to compare her results to results obtained with data from Uranus’ moons. This is of course a long-term vision: despite the Planetary Science Decadal Survey strongly recommending a mission to Uranus earlier this year and there being a convenient launch window in the early 2030s, we can’t forget the 13-year-long journey to the ice giant.

Regional mapping of an area on Tethys

All these fascinating insights into our solar system’s formation and evolution make Friday’s spectacle that more inspiring!

Cover image: 7 planets line up and Moon, R. Kelly
Image Credits:
1 - Top-down view, JPL HORIZONS with additions by B. King
2 - Alignment on the 17th, M. Shaw
3 - Alignment on the 20th, A. Krivenyshev
4 - Alignment on the 21st, M. Lee
5 - Clay-bearing sediment, NASA/HiRISE/University of Arizona
6 - Vortices near Jovian North Pole, NASA/JPL-Caltech/MSSS/SwRI/R. Sankar
7 - Jupiter and two of its moons, NASA
8 - Map of sulfur dioxide, NASA/JPL/B. Jonsson/Becker et al., 2022
9 - Fig. 5 from Ferguson et al., 2022

Finally ! Gaia’s Third Data Release

Maurane Gisiger — Thu, 16 Jun 2022 09:58:16 +0000

Finally ! Gaia’s Third Data Release

Maurane Gisiger Thu, 06/16/2022 - 09:58

I attended the RAS-hosted ESA event for you !

All the questions asked by the scientific team behind Gaia

On Monday the 13th of June, the world of astronomy was holding its breath waiting for the release of the Global Astrometric Interferometer for Astrophysics (Gaia) mission’s third set of data. For more than 8 years, this European space observatory has been conducting astrometry, i.e., determining the position and motion of Milky Way stars more accurately than ever, in an attempt to create the largest 3-D map of our galaxy. The very first Data Release, DR1, occurred in 2016 when the Gaia team revealed the astrometric details of 2 million sources. In past data releases, we also have the DR2 in 2018, allowing a huge jump with 1.332 billion stars, and an Early Data Release 3 (EDR3) which was already made available on the 3rd of December 2020, adding another 136 million stars to this catalogue.

And that's only the Early DR3 !

The full DR3 is even more exciting with its 2 billion sources analysed, notably in that it provides many more “Specific Objects Studies”, including of binary stars, of variable stars like Cepheids or RR Lyrae stars and of exoplanet transits, but also including objects from way beyond the Milky Way, like quasars – with more than 6 million candidates detected. Over a million stars in our neighbour galaxy of Andromeda were observed in the Andromeda Photometric Survey. Closer to home, many Solar System Objects were tracked, too, with 150 000 asteroids’ orbital parameters having been catalogued, of which 60 000 asteroids having their reflectance measured – this allows to determine their chemical composition.

All the asteroids that Gaia observed, as they would have been at the time of DR3

For the first time, spectral information was released on top of all the astrometric data. It has notably been used to estimate 6 million stars’ metallicity (their content in elements heavier than Helium), the full chemical abundance profile of 2.5 million of these stars. Overall, DR3 now makes Gaia the largest low-resolution spectroscopic survey and the largest collection of astrophysical data for Milky Way stars.

A spectrum obtained with the Radial Velocity Spectrometer (RVS). It is a mean spectrum since the star was spotted multiple times by Gaia. Such mean spectra have been obtained for 1 million sources, for the first time in DR3.

As one of the speakers at the event put it, Gaia can see and watch stars with the tools to conduct astrometry, it can taste and smell to obtain chemical information via spectroscopy, and it can also hear by using instruments for asteroseismology. Surprisingly, Gaia observed “starquakes” with this technique – some stars “vibrate”, causing the equivalent of incredibly massive tsunamis at the surface of the star, changing the shape of the star in a way that is actually detectable for Gaia !

It’s worth mentioning that the Royal Astronomical Society-hosted event for DR3 took place in Goonhilly, described as the UK's Gateway to Space. This “Earth Station” indeed hosts a 32-meter antenna which is used by ESA to download data from the Gaia probe. You can listen to a recording of the full event yourself at: https://www.youtube.com/watch?v=rjCaRSJMIhc , where the speakers will describe how the spectra were calibrated against those of objects like, among others, Standard Stars and Emission Line Objects, what DR3 can say about the InterStellar Medium, how there are also new photometric results in DR3, or how line-of-sight radial velocity data for 34 million stars helps astronomers understand over 1/3 of the Milky Way’s stars motion.

The researchers who already had access to the data before it being made available to everyone (yes, that includes you !) are publishing papers at an astonishing rate, at least 4 or 5 per day. In March, the Shaw Prize in Astronomy was awarded to Lindegren and Perryman “for their lifetime contributions to space astrometry, and in particular for their role in the conception and design of the European Space Agency’s Hipparcos and Gaia missions”. There are many more exciting discoveries that will be made with the data from Gaia’s DR3 !

ESA's Cosmic Observers

All image credits to ESA.

Monster galaxies' evolution from new HST mosaic image

Maurane Gisiger — Thu, 09 Jun 2022 08:25:02 +0000

Monster galaxies' evolution from new HST mosaic image

Maurane Gisiger Thu, 06/09/2022 - 08:25

After breaking its own record for the farthest star ever observed, the HST shows us its largest near-infrared image !

By using a fairly new technique with the HST known as Drift And SHift (DASH), the astronomers were able to capture multiple shots and combine them into a “mosaic”. FDASH also allowed them to take 8 pictures per Hubble orbit, effectively dividing by 8 the time required to cover the whole area that was imaged. This is a great improvement over the COSMOS-DASH image released in 2019 (0.66 deg²), since now the area is almost 6 times the apparent size of the Moon in our night sky (1.43 deg²) !

DASH technique

The researchers obtained this new 3D-DASH image with the HST's Wide Field Camera 3 (WFC3) in near-infrared wavelengths, which is useful to spot very distant galaxies, i.e., very early ones. In this huge set of galaxies, they seek to identify rare occurrences such as the Universe's most massive galaxies, highly active black holes and AGN, and galaxies on the verge of colliding and merging. One of the main authors of the study, who started working on the project in 2015 as a student, focuses on the first category of “monster” galaxies in an attempt to understand how these behemoths are formed and evolve.

Grid of some galaxy images from COSMOS-DASH
Most massive star-forming galaxies in the 3D_DASJ survey

Another telescope that will observe in infrared wavelengths is the James Webb Space Telescope, however it was designed for close-up observations rather than to conduct such a wide survey. The next infrared space telescope with the capability to provide sharp wide-field images will be the Nancy Grace Roman Space Telescope, that should launch in the mid-2020s. For now, you, too, can explore an interactive online version of the 3D-DASH image in which you can move around the mosaic, zoom in and out, and look at it in specific infrared wavelengths.

Equally important to understand the structure of our Universe is having a good picture of the intergalactic medium (IGM). An incredible step forward was taken in that direction this week, thanks to the Instituto de Astrofísica de Canarias (IAC)’s new machine learning algorithm, Hydro-BAM. With it, they model Lyman-alpha forests: as light from a distant galaxy like a quasar journeys towards us, some of it gets absorbed by clouds (or, “trees”) of hydrogen gas, resulting in this Lyman-α set of lines in the quasar’s spectrum.

Thanks to the computational model, the connections between the quantities of intergalactic gas, dark matter and neutral hydrogen allow researchers to predict the absorption pattern in the Lyman-alpha forest

The upshot of the IAC’s research is not only that Hydro-BAM drastically reduces the computing time required for these simulations, but there is also physical insight. Namely, that the interactions of the ingredients of the IGM (hydrogen gas, dark matter and neutral hydrogen) affect the structure of our Universe on its largest scales, and they specifically do so in a hierarchical manner as illustrated above. We can then trace the evolution of structures and compare the results from the models to what we see today in observational surveys such as those conducted with the Dark Energy Spectroscopic Instrument or the Subaru Prime Focus Spectrograph.

Distant galaxies and the space between them still have a lot to reveal to us. Many more hours of observations, with a number of telescopes, are needed for us to complete our picture of the Universe's structures and their evolution.

Cover Image: Some galaxies in the 3D-DASH image, L. Mowla
Image Credits:
1 - DASH technique, Mowla et al. (2022)
2 - Some galaxies in the COSMOS-DASH image, Mowla et al. (2019) / Cutler et al. (2021)
3 - Galaxies in the 3D-DASH image, Mowla et al. (2022)
4 - Hierarchical model, F. Sinigaglia

The hazy and snowy blue worlds of our Solar System

Maurane Gisiger — Thu, 02 Jun 2022 10:15:28 +0000

The hazy and snowy blue worlds of our Solar System

Maurane Gisiger Thu, 06/02/2022 - 10:15

Why is Uranus “cyan” and Neptune “azure” ?

Uranus and Neptune have roughly the same size (Uranus is only 1500 km larger than Neptune), the same mass (14 Earth masses for Uranus, 17 for Neptune) and the same composition (atmospheres are predominately hydrogen, helium, and methane, mantles are mostly water, ammonia, and again, methane). Despite this, their slightly different colours have been puzzling astronomers. The two ice giants haven't been visited since the Voyager missions in the 1980s, but have recently made it on NASA's priorities list and it is extremely likely that a probe to study Uranus will be launched during the 2030s, arriving at the planet sometime around 2044.

The two planets are very similar

Anyway, with data across a wide range of wavelengths from the Hubble Space Telescope, the NASA Infrared Telescope Facility, and the Gemini North telescope, astronomers were able to devise a model that accounts for the colour difference. In this model, there are three layers of haze, containing aerosol particles (essentially, clouds). The middle layer is thicker on Uranus than on Neptune. Moreover, on both planets, methane ice condenses onto the aerosol particles in this layer, causing “methane snow”, however Neptune’s atmosphere is generally more turbulent, so that it is more efficient at forming this otherworldly snow. Equivalently, Neptune “gets rid of” this layer of haze more easily, giving it a deeper blue colour.

Diagram of aerosol layers

As a nice additional side-result, this model gives an explanation for the occasional dark spots that have been … spotted in the atmospheres of the two ice giants. The researchers demonstrate that the deepest layer, which is a mixture of hydrogen sulphide ice and particles produced by the interaction of the planets’ atmospheres with sunlight, is responsible for these. The darkening of spots in that layer could be caused by storms and other atmospheric currents, similarly to the Great Red Spot on Jupiter.

Another model presented this week revises our understanding of the Sun, specifically its chemical composition. By considering our star’s rotation and magnetic fields, the astronomers from the University of Geneva, Switzerland, and the University of Liège, Belgium, were able to predict the abundances of certain chemical elements more precisely than with the previous standard model. That simplified model worked reasonably well until the early 2000s, point at which solar astronomers obtained improved measurements of the abundance of chemical elements in the Sun and helioseismic measurements (much like with “terrestrial” seismology, measuring the oscillations). The latter allows to conclude about the Sun’s internal structure.

The model includes the history of the rotation of the Sun

By adding the evolution of the Sun’s rotation and the magnetic instabilities that arise from it, a more consistent picture of the transport of elements inside the Sun emerges in the new model. Most importantly, the abundance of helium in the Sun’s outer layers was correctly prognosticated. Still, there are some challenges left. In particular, we know from helioseismology that the convective zone begins 199 500 km below the surface, and the model is 10 000 km off – this is better than past estimates from other theoretical models, but the difference with observations remains to be explained. Nevertheless, the updated model will now be used to re-evaluate the masses, radii and ages of solar-type stars, as this sort of analysis is typically done relative to the Sun. This, in turn, will have implications notably for our search for exoplanets.

A clearer view of ice giants and of Sun-type stars - two promising steps forward in understanding how stellar systems as a whole form and evolve.

Cover Image: Uranus and Neptune from Voyager 2 fly-by, NASA/JPL-Caltech/B. Jónsson
Image Credits:
1 - Uranus and Neptune Ring systems, R. Kelly
2 - Diagram of ice giants' atmospheres, International Gemini Observatory/NOIRLab/NSF/AURA, J. da Silva/NASA /JPL-Caltech /B. Jónsson
3 - Solar model, S. Ekström / UNIGE

Do you fancy sharing a ride to space ?

Maurane Gisiger — Wed, 25 May 2022 20:39:21 +0000

Do you fancy sharing a ride to space ?

Maurane Gisiger Wed, 05/25/2022 - 20:39

The Transporter 5 and Starliner missions, and more news on the future of space exploration.

SpaceX’s Transporter 5 launched at 18:35 GMT on the 25^th May to bring 59 CubeSats into orbit. As a “rideshare” mission, some of these CubeSats contain experiments like the one from their customer GHGSat, which operates a network of satellites that detect methane emissions from orbit, another one was in-space infrastructure services provider Momentous' inaugural flight, but others are much more unusual. Indeed one of their customers is Celestis, a company that provides “memorial spaceflight experiences” – yes, it is literally bringing a deceased person’s ashes (or a DNA sample) to space. In fact, this one CubeSat that Celestis booked on board of the Falcon 9 rocket contains the (partial) remains of 47 people. While SpaceX is much more well known for its two successful crewed launches to the International Space Station (ISS), this is a much less obvious aspect of the blooming space exploration business.

The return of the Falcon 9 booster after launching its Transporter 5 mission

Now it’s Boeing that seems to enter the “astronaut taxi service” business to the ISS. On the 19^th May, the United Launch Alliance spacecraft launch service provider sent an ATLAS V rocket loaded with Boeing’s Starliner capsule into space. Just a day later, Starliner, unmanned but with 225 kgs of food and other supplies, reached the ISS. Following its undocking at 18:36 GMT this Wednesday, 25^th of May, Starliner, loaded with empty tanks of gas that were used to provide oxygen to the astronauts on board, is going to reach the Earth in a few hours. After many disappointments with their first Orbital Flight Test (OFT), Boeing’s OFT-2 might be their entry ticket to the business of crewed flight. If NASA does certify Starliner after this past week’s events, a crewed test to the ISS could happen as early as the end of this year.

Starliner docked to the ISS

It must be noted that the current Ukraine-Russia conflict does raise questions about the future of the ISS, especially after Russian space chief Dmitry Rogozin announced in an interview that discussions are underway about Russia leaving the ISS as retaliation for economic sanctions. This is not an official statement though, and the Russian space agency Roscosmos has confirmed that they would abide by the official policy that they must inform their partners about the end of their work on the ISS with a year’s notice. For now, the contract binding ISS partners, including Roscosmos, expires at the end of 2024. On the other hand, NASA has made it clear that they would prefer extending the station’s lifetime to the early 2030s.

Matthias Maurer carries out a spacewalk outside the ISS on March 23, 2022. At the end of the EVA, water was discovered pooling inside his helmet

However, NASA has issues with its Extra-vehicular Mobility Units (EMUs) as these spacesuits have been found to leak water. This problem was first discovered in 2013 with Maurer's Extravehicular Activitie (EVA), but has repeated itself now. This has led NASA to pause any upcoming EVAs until the source of this systematic problem is found. EVAs are necessary to allow astronauts to perform maintenance and upgrade tasks on the ISS, and functioning spacesuits are obviously an absolute necessity for successful EVAs, as each time astronauts spend on average between 6 and 8 hours “outside” of the ISS - in the vacuum of space. In case of an emergency, Roscosmos’ Sokol spacesuits can still be used.

Ground prototype of NASA’s new Exploration Extravehicular Mobility Unit (xEMU) for the Artemis mission, unveiled in 2019

NASA’s recent developments in spacesuit technology have focused on preparing for the Artemis Moon mission, for which the spacesuit has to fulfil different requirements than an EVA. As well, since the ISS will get decommissioned within the next decade, it is unlikely that a new generation of EMUs for the ISS will be created. In fact, a team at NASA’s Jet Propulsion laboratory has predicted that humans will reach the asteroid belt by 2073, an achievement for which, besides an incredible other set of technological challenges to be overcome, appropriate space-clothes will also be need. To obtain their estimate, this team considered factors such as technological progress rate and economic growth, including the partnerships with private companies like SpaceX and Boeing.

I will leave you with their conclusion: “Our model suggests human landings on worlds beyond the Moon and Mars may well be witnessed by many alive today”.

Cover Image: ISS, NASA
Image Credits:
1 - Falcon 9 booster return, SpaceX
2 - Starliner space capsule docked at the ISS, ESA
3 - Maurer on EVA, NASA
4 - xEMU, NASA/J. Kowsky