Water Discovered on Mars! (Again.)

It's a bit of a running joke amongst planetary scientists that any research discussing water (in any form) on Mars will get reported in the press with a breathless headline. Year after year, somehow the 'discovery' of water on Mars persists as a topic of great interest. One of our MSc students digs into this phenomenon below. Luckily, she isn't working on astrobiology topics - that often leads to headlines about aliens.
(Image above: Jezero crater, as it might have appeared when filled with water in the past)

By Grace Bischof

Recently, fellow PVL member Charissa Campbell was involved in a JPL press release detailing the Martian clouds she captured in her Cloud Altitude Observation. The images consisted of beautiful clouds drifting across the Martian sky, likely composed of CO2-ice due to their high altitude in the atmosphere. I spent some time reading the replies to the press release on social media, many of which pose questions about the composition of the clouds on Mars. “Clouds means water?” writes one of the commenters. Meanwhile, “What are the clouds made of? [because] there ain’t no water vapour floating around on Mars, right?” inquires another.  

Well, I have some good news for everyone: there is water on Mars! But before you call your local newspaper to report the exciting revelation, I have some explaining to do. The presence of water on Mars has been confirmed since the late 1960s, when water vapour lines were detected in spectra of Mars observed with an Earth-based telescope. Since then, water has been “discovered” on Mars over and over and over again (see: any Daily Mail article about Martian water). So, let’s clear this up. Water exists on Mars in both vapour and ice form. The confusion arises when we consider the way we talk about water in day-to-day life. In regular conversation, we say “water” when we mean liquid H2O, and “ice” when we mean solid H2O. This verbiage doesn’t hold in planetary science settings because “ice” to refers to any solid form of a condensable species: for example, CO2-ice or H2O-ice. Because of this confusion, the lack of liquid water leaves people believing there is no water whatsoever.

So, let’s take a closer look at the water on Mars. Mars’ atmosphere is much thinner and has much less water vapour than Earth’s atmosphere. However, the amount of water vapour is sufficient to condense to form water-ice clouds in the atmosphere. Each Mars Year, when the planet is at its aphelion position (the furthest point from the sun) a belt of water-ice clouds forms in the equatorial region of the planet, called the Aphelion Cloud Belt. These clouds have been observed by orbiters around Mars and cameras on the surface, notably by the Curiosity rover. Water-ice clouds exist in other regions, as well, such as in the Martian Arctic. The Phoenix mission captures images of fluffy clouds drifting past its landing site during the second half of the mission. The Surface Stereo Imager and lidar onboard the lander were used together to find evidence of water-ice fog near the surface of the lander. The Phoenix mission was also the first mission to capture precipitation (snow) falling from the clouds.

The other common place to find water on Mars is as water-ice in the subsurface. The Phoenix lander was equipped with a robotic arm to dig into the Martian soil. They were able to find ice in the area around the lander at many depths, ranging down to 14 cm. At both the north and south poles you can find a large polar cap primarily composed of water-ice covered by a layer of CO2-ice. Areas of the south polar cap resemble Swiss Cheese, where pits in the CO2-ice layer expose water-ice beneath. PVL member, Alex Innanen, has examined the Swiss Cheese pits to determine if the water vapour sublimated from the Swiss Cheese contributes substantially to the overall global water vapour abundance. 

So, what about that coveted liquid water? Well, it’s complicated. Presently, no bodies of liquid water can exist on the surface of Mars. The atmosphere is so thin that exposed water-ice sublimates straight to water vapour when heated and deposits back to ice when cooled. Geomorphic evidence, such as river deltas, show us that Mars had liquid water on the surface in its past. In 2018, radar analysis of Mars’ south pole saw evidence of a subsurface liquid-water lake. It was theorized the lakes would be extremely salty, bringing the freezing temperature down and allowing the water to stay liquid. In 2021, a York U professor, Dr. Isaac Smith, released a paper explaining that the radar observations are better described by hydrated and cold clay-rich deposits (https://doi.org/10.1029/2021GL093618), rather than salty lakes. 

Liquid water on Mars is an exciting notion because it leads to many questions about the habitability of the planet, both past and present. But liquid water is not the only interesting phase of water – it is clear we really love the clouds here at PVL. Nonetheless, if liquid water is ever found, you can sure expect to see a bold headline declaring “Water Discovered on Mars!”, in which case, you can refer back to this blog post. 

I, Robot – InSight’s Struggle to Keep the Lights On

Our spacecraft are more than just our robotic avatars on other planets. They carry our culture with them, sometimes literally as with the Voyager golden record. But they also have an effect on those who remain back here at home. This can take the form of becoming the topic of memes, of having fan fiction written about them or being completely anthropomorphized. This week, undergraduate student Vennesa Weedmark considers the Opportunity Rover, InSight lander and their ultimate fate.
Image above: InSight's first selfie.

By Vennesa Weedmark

For as long as humans have been launching things into space, we’ve been anthropomorphizing them as extensions of our global self, bravely venturing into the void. These little (or sometimes very large) friends are given nicknames, celebrated, and eventually, mourned. Opportunity, a robotic rover that lived 55 times longer than its planned 90 sol lifetime, drove over 45 kilometers, knew its own birthday, gained a massive online following, and became a symbol of perseverance in the face of overwhelming odds. When NASA finally confirmed its death on February 13th, 2019, and its last message was translated as “My battery is low and it's getting dark”, there was an upwelling of condolences and life-celebrating responses across the internet.

I may have shed more than one tear.

Now, the end seems nigh for InSight aka. Interior Exploration using Seismic Investigations, Geodesy and Heat Transport. Designed to study the interior of the red planet and determine the rate of Martian tectonic activity and impacts, the planets “vital signs”, it launched in 2018 and has been active on Mars for over 1100 sols, slightly beyond its planned mission duration.

Since landing, it has recorded the first sounds of Martian winds, attempted to dig into the surface of Mars, detected marsquakes, found fluctuations in the magnetic field at the landing site, and provided invaluable information about soil at the landing site and the possible methods for drilling into Mars, and successfully emerged from an emergency hibernation caused when its solar panels became covered with dust. Since that first storm, InSight has been trying to clear the sand from its panels using saltation. By using its robotic arms to sprinkle sand near its solar panel, the sand would blow away, touching the solar panels and taking some of the dust with it as it left the solar panel. This, luckily, resulted in a temporary boost in power.

Then, because the bad luck of previous years isn’t done with us yet, January 2022 brought another drop in sunlight due to a regional dust storm, causing InSight to re-enter safe mode. The storm that shuttered InSight was only about 18% as strong as that which brought about the demise of Opportunity, and its safe mode ended again with no lasting signs of damage.

The overarching problem is what will become of InSight as its access to life-giving sun continues to decline, and what working on reduced power will do to the experiments and tests that it has yet to complete. As power drops, it’s saltation cleaning method will also become more difficult to perform.
Opportunity’s arrays were cleaned regularly by atmospheric activity, but InSight has continued to accumulate dust, and its outlook is looking increasingly dim (pun fully intended). Obviously, efforts to clean the Solar panels continue, but short of a “cleaning event”, it is likely that we’ll be mourning another brave explorer in the next year.

Like Oppy, InSight is active on social media and has a sizeable following, tweeting “Skies seem to be clearing overhead, so I’m out of safe mode and back to more normal operations”, as it emerged from its most recent slumber. Hopefully I won’t cry as much when InSight sends its final tweet. 

Note: while two members of PVL (Charissa Campbell and John Moores) are collaborators of the InSight Team, this post is completely independent of our work on that mission and was written by a member of our lab who is not affiliated with the InSight mission.

SpaceX, Starlink, and the Commercialization of Space

This week, masters student Conor Hayes tackles a thorny issue: how to balance the expansion of private actors in space and the benefits their work can have for those of us on earth with the needs of astronomical research. It's not inconceivable that such an expansion could change the night sky forever, not just for scientists working with sensitive instruments, but also for most of the world's city-bound population for whom a starry sky could be replaced by criss-crossing lights. Must we give up wonder to achieve a better life for each another? Image: 19 Starlink satellites unintentionally imaged by the Blanco Telescope at the Cerro Tololo Inter-American Observatory. (CC BY 4.0, NOIARL/CTIO/AURA/DELVE, https://nationalastro.org/news/starlink-satellites-imaged-from-ctio/)

by Conor Hayes

One of the consequences of the way that our economic systems are structured is an ongoing competition between public and private interests to exploit various resources. This competition rolled through astronomical Twitter like a bowling ball through a set of pins in November 2019, when the image above first made its way onto the internet.

Taken using the Victor M. Blanco 4-metre telescope at the Cerro Tololo Inter-American Observatory in Chile, it shows 19 bright streaks caused by a train of Starlink satellites passing through the telescope’s field of view. Unsurprisingly, this greatly reduced the quality of the data, leading to widespread concern about the long-term impact of Starlink on astronomical observations.

The mere fact that Starlink satellites are visible in telescope imagery isn’t the problem. Outside contamination of CCD images is nearly inevitable with a long-enough exposure time. If you ever get a chance to look at raw data from a telescope, you will probably see similar, though shorter, bright streaks caused by cosmic rays impacting the detector. Furthermore, artificial satellites have been occasionally ruining images for as long as there have been a significant number of them in orbit. So what is the problem then?

Part of what concerns astronomers about the Starlink constellation is the sheer number of satellites involved. SpaceX currently has authorization to launch 12,000 (!) Starlink satellites, and has submitted paperwork to approve another 30,000 (!!). For comparison, the United Nations Office for Outer Space Affairs currently lists about 10,400 objects launched into space since 1957. When the constellation is completed, the number of visible Starlink satellites may even outnumber visible stars in heavily light-polluted areas like Toronto. Given that the constellation is intended to surround the Earth at many different orbital planes, having a small handful of Starlink satellites streak across your telescope’s field of view may become a regular occurrence.

In addition to antagonizing astronomers who work in the optical, the development of Starlink has also worried radio astronomers. Ground-based radio astronomy is already hard enough thanks to the fact that many of our modern-day technological conveniences are constantly blasting radio waves into the environment. Consequently, much like how optical telescopes are located in dark areas away from major population centers, radio telescopes are often surrounded by “radio quiet zones”, large swaths of land where radio emissions are strictly regulated. But when those radio sources are passing overhead, as the Starlink satellites will be, those radio quiet zones may become significantly louder.

If nothing else, the conflict over Starlink shows how vital it will be for the scientific community and private businesses to communicate with each other to find a mutually beneficial way forward. Though SpaceX is now looking into ways to make their satellites less bright, including darker paint, sunshields, and shutting off transmissions when passing over radio quiet zones, these kinds of after-the-fact adjustments are not sustainable in the long term. Though I personally find the commercialization of space somewhat distasteful, I also recognize that as the barrier to entry gets lower, thanks in large part to the innovations championed by companies like SpaceX, it is almost inevitable that commercial interests will want to spread outward. Because astronomers have held a near-total monopoly on space for so long, learning to let other people in will be a difficult process, one that will require sustained, genuine cooperation from all interested parties.

I didn’t start writing this post with the intent to argue for the termination of the Starlink program. It’s a difficult needle for me to thread because on one hand, I am an astronomy grad student whose future career could be hindered by a poorly-managed privatization of space. On the other hand, I recognize that SpaceX’s goal with Starlink is an admirable one. The past year has demonstrated how global access to reliable, high-speed internet is now more of a necessity than a luxury, and demanding that Starlink be shut down just because of the challenges it presents for astronomy would be irresponsible and short-sighted. This goes both ways, of course. It was incredibly disheartening to scroll through some of the replies to the original tweet and see how many people were calling ground-based astronomy little more than a vanity project with no real worth to humanity (Elon’s tweets dismissing astronomers’ concerns out of hand and telling them that they were overreacting certainly didn’t help, either).

Though I don’t have any concrete solutions right now, it seems increasingly likely that, as is the case in so many other areas of our society, the responsibility for dealing with the monumental shifts in the way that the private and public spheres interact with each other beyond Earth will ultimately fall upon the next generation of astronomers currently working their way through their undergraduate and graduate educations. I do believe that we can eventually strike the right balance, but I hope that time comes before unregulated, antagonistic competition severely damages our ability to look up at the sky and wonder what lies beyond our home.

Arecibo, A Giant in the Field

This week, Conor Hayes pays tribute the Arecibo Radio Telescope. You may know it in connection with SETI (or perhaps from movies!) but its ability to make observations along the ecliptic made it one of Planetary Science's most effective instruments. Unfortuately, the telescope recently experienced a structural failure which will require its demolition. 

Photo above:  The Arecibo Observatory as seen in June 2019. (CC BY-SA 4.0, https://commons.wikimedia.org/wiki/File:Arecibo_Radiotelescopio_SJU_06_2019_7472.jpg)

by Conor Hayes

On November 19, 2020, the astronomical community lost a (literal) giant. Following the failure of two support cables that made repair work dangerously unsafe, the National Science Foundation announced that they would be decommissioning the Arecibo Observatory. This 305-metre radio telescope has faithfully watched the skies for nearly 60 years, during which time it became perhaps the most well-known telescope on the planet, appearing in popular media like GoldenEye, Contact, and The X-Files. Its loss will be felt by all of us, most acutely by those who have dedicated their lives to radio astronomy. Given this, I felt it was appropriate to write a little bit about radio telescopes in general, as well as some of the notable discoveries made using Arecibo.

Why was Arecibo so large? When designing a new telescope, you need to balance the quality of the data it can output with how expensive it will be to build. The resolution of images taken by a telescope is covered by the following equation: R = λ / D, where R is the resolution, λ is the wavelength of the light you are observing with, and D is the diameter of the telescope’s primary mirror or objective lens.

From this equation, you can see the two-front war that radio telescopes are fighting. As with all telescopes, the larger your light collection area is, the higher resolution your data will be. However, radio telescopes face an additional problem, in that radio waves have the longest wavelengths of all electromagnetic radiation. Because the wavelength appears in the numerator of the resolution equation, observations done on, say, a 10-metre radio telescope will be significantly lower resolution than observations done on a 10-metre optical telescope. This means that radio telescopes must be significantly larger than those used to observe at shorter wavelengths if they want to achieve a comparable resolution. Fortunately, because radio waves are less impacted by small-scale imperfections in the telescope’s surface, we can get away with constructing them out of sheets of metal (or even a fine metal mesh!) rather than carefully-polished mirrors, greatly reducing the cost.

Of course, actually building and maintaining such a large structure is still massively expensive, to the point that Arecibo spent much of the last 20 years of its life under constant threat of being shut down due to funding shortfalls. To avoid this, many radio observatories, like the Very Large Array (VLA) in New Mexico, the Atacama Large Millimeter Array (ALMA) in Chile, and the upcoming Square Kilometre Array (SKA) in Australia and South Africa, use a technique called very-long-baseline interferometry (VLBI) to combine a large number of smaller telescopes into one telescope with a much larger effective collection area. VLBI was most recently leveraged to combine many radio telescopes across the planet into the Event Horizon Telescope, which took the first direct image of a black hole.

As the largest radio telescope in the world from its completion in 1963 to the construction of the Five-hundred-metre Aperture Spherical Telescope (FAST) in 2011, the Arecibo Observatory was at the forefront of radio astronomy and contributed to a number of important scientific discoveries.

In our own Solar System, Arecibo was used to determine that Mercury has a rotational period of 59 days, rather than being tidally locked as was previously assumed. Relevant to my own research into ice in the permanently shadowed regions (PSRs) of the Moon, Arecibo made some of the first radar measurements of ice in the PSRs of Mercury, observations that were later confirmed by the MESSENGER spacecraft.

Elsewhere in the universe, Arecibo was responsible for a number of other “firsts.” In 1968, scientists using Arecibo measured the rotational period of the Crab Nebula pulsar, which provided the first direct evidence of the existence of neutron stars. Just six years later, Arecibo produced its first Nobel Prize-winning research in the form of the discovery of a binary pulsar system. This system was found to have a gradually decreasing orbital period, which is consistent with energy loss in the form of gravitational waves (though gravitational waves would not be directly measured until 2016). Though the search for exoplanets has been popularized by space telescopes like Kepler and TESS, it was actually Arecibo that first found extrasolar planets due to irregularities in the measured rotational period of a pulsar. To date, one of these still holds the record for the smallest known exoplanet, with a mass around twice that of the Moon.

Finally, Arecibo played a key role in the Search for Extra-Terrestial Intelligence (SETI) and Messaging to Extra-Terrestrial Intelligence (METI) programs. Arecibo was one of the primary telescopes used by the SETI Institute to listen for possible communications from extraterrestrial life, and in 1974 broadcast a short message containing information about humanity and our location in the galaxy to M13, a globular star cluster located 25,000 light years away. Although seen as reckless and possibly dangerous by many, it is widely accepted that nothing will come of this message due to the vast distances involved.

 

The Arecibo Message, which was sent from the observatory towards the globular cluster M13 in November 1974. It contains information on the genetic structure of humans, our physical characteristics, and how to find us. Many felt this was a dangerous amount of information to be sending to a hypothetical alien civilization whose motivations were unknown. (CC BY-SA 3.0, https://commons.wikimedia.org/wiki/File:Arecibo_message.svg)

The Arecibo Observatory will certainly be missed, but it leaves behind a vast and rich legacy of scientific discoveries. With FAST now operational and the 100-metre Green Bank Telescope still in good working order, along with a number of existing and new interferometric arrays around the planet, the world of radio astronomy continues to be well-served. Though the end of this particular telescope’s career was perhaps more abrupt than some might have imagined, it is leaving us having done more than its fair share of the hard work of advancing our knowledge of the universe.

How far can a golfer hit a drive on Mars… and the Moon?

Click Here to view an animated version of the figure above!

This week, undergrad Noah Stanton takes on a burning question in comparative planetology: how would a change of venue to another planet or Moon affect one's golf game? Read on for his deep-dive! Reminds me a little of some of the tangents I followed in my earlier years!

by Noah Stanton

Have you ever been watching golfers playing on Pebble Beach and thought, ‘What would happen if he or she took that shot on Mars or the Moon?’. I’d assume no, but I am here to tell you this important information. In order to figure out a way to model a golfer’s shot let’s start somewhere we know a little bit better, Earth. 

Modelling a golf shot involves bio-mechanics, aerodynamics, elasticity of the golf ball, etc., which is maybe outside the abilities of a mere blogpost. I will need to make some assumptions, focus on some parts of the swing, and ignore the rest. The two modeled parts of the swing will be:

1)    The initial contact and acceleration due to the club-head hitting the ball
2)    The flight of the ball after the initial contact

Video Game provides opportunity for research on impactors

In his inaugural post, PVL Summer Undergraduate Michael Tabascio takes a look at a most unusual crater that appears in popular culture, on the map of the game "fortnite" as pictured above. As frequent readers of this space will appreciate, I think it's absolutely critical to bring the public along for the ride that is planetary exploration. As such, depictions of planetary processes like these offer a unique opportunity to connect our work with that public experience and to deepen the appreciation of both perspectives.

By Michael Tabascio

Fortnite is a hunger games style third person shooter has taken the world by storm, with the objective to be the last one alive by eliminating your opponents. It can be said with great assurance that Fortnite is the biggest game of the year, with the map evolving every couple months. Perhaps the most notable change came in May, when the map was struck by a meteor leaving a gigantic crater in the middle of the map. Using the dimensions of the crater, the direction and angle of the meteor, as well as the material of both the meteor and the ground beneath it, we can estimate what the size of the meteor was that hit the map.