Five Pictures from Ten (Earth) Years of Curiosity

 

The photos that our robot geologists (and robot atmospheric scientists) bring back to us from other worlds help us to relate to these places on a human scale. No one at the PVL have looked at more images of Mars than Alex and so, who better to take us on a visual trip down memory lane on this auspicious anniversary?

By Alex Innanen

August 6^th marks 10 (earth) years since Curiosity (AKA the Mars Science Laboratory or MSL, because space people love a good acronym) landed in Gale Crater on Mars. If you’ve been around the blog, you’ll know that many PVL-ers have had the chance to work on the mission (myself included) and there have been a plethora of posts over the years about what doing ENV operations is like, or what cool science MSL is doing, or other big mission events, like the 2018 global dust storm or passing 2000 sols on Mars. To add to this collection, and to celebrate 10 years of Curiosity (or 5 Mars years, a milestone reached this most recent January), I’m going to journey through some of my favourite pictures the rover has taken over the past decade.

First we have the above picture, a classic selfie. Curiosity regularly poses for MAHLI (the Mars Hand Lens Imager) to take these self portraits, which are actually mosaics of tens of MAHLI images. There’s a fantastic video of Curiosity’s arm moving around to get all the pictures that make up a selfie. This particular selfie was captured during the 2018 global dust storm, and you can see dust in the background obscuring the crater rim. This is the same dust storm that heralded the end of Opportunity’s mission, but Curiosity came through with lots of science (and nifty pictures) to show for it.

Going all the way back in time to 2012, this is a 360° panorama of Curiosity’s landing site, named ‘Bradbury’ for the sci-fi author Ray Bradbury. Right in the centre of the picture is Mount Sharp (or Aeolis Mons), the mountain in the centre of Gale Crater. Mount Sharp is made up of sediments laid down in Gale Crater over a long period of Mars’ history, and as Curiosity has climbed up it, it’s as though the rover has been travelling through that history. But first it had to get to the base of Mount Sharp, a trip which took around 2 years trundling through the remnants of ancient lakes and rivers. I love looking at this panorama because it gives a great idea of how far Curiosity has traveled – over 28 km and 600 m of elevation, now. It's also a great ‘big picture’ shot – every new location Curiosity visits is (in my humble opinion) stunning and unique in its own way, with so much new and exciting to look at. This image lets you take a step back and take it all in.

It would be remiss of me to not include a cloud picture, so here it is, my absolute favourite cloud shot. I may be slightly biased, as I was on shift when this image was planned, but it’s so dramatic, with the cliff face (called ‘Mont Mercou’) in the foreground and the glowing clouds behind. These are Noctilucent clouds, which means ‘night shining’, and were captured at twilight early this Mars year (which was actually March of 2021 – Mars years are long). These kinds of clouds are high up in the atmosphere, and are illuminated by the setting sun, even visible when the sun has gone below the horizon. This is what makes them appear to glow, still being illuminated while the rest of the sky darkens. These particular twilight clouds seem to form more readily in Gale crater near the beginning of the Mars year, something the team discovered in Mars year 35. At the start of Mars year 36 (the current Mars year) we started looking for them and were not disappointed. One of the great things about Curiosity having been on Mars for so long is the fact that we can see yearly repetitions like this and come up with a better idea of what the Martian environment is up to year after year.

Mars’ blue sunset is spectacular and well known to fans of the ‘red’ planet. But “what colour is the Martian sky?” is a question I’ve been asked more than once by those less familiar with Mars. And it’s a great question! Sometimes – like in this picture or the cloud picture above, the sky looks more blue, almost like earth’s sky. But at other times, like in the selfie or the Mount Sharp panorama, it looks more orange or yellow. There’s a few factors behind this – often images are colour-corrected (‘white-balanced’) to show what a scene might look like under earth-like lighting. This can help scientists interpret features within a scene, making them look more familiar to better compare to earth, but doesn’t accurately represent what you might see if you were standing on the surface of Mars, which would be more of a yellowy-orange sky.

Except when you get close to the sun, like in this sunset picture. Much like how earth’s scatters light, giving us a blue sky, so too does dust in the Martian atmosphere, but the blue wavelengths of light mostly scatter forwards, so the blue colour appears closer to the sun. As the sun sets, there is more atmosphere and more dust for the light to scatter through, so that blue effect near the sun becomes more pronounced. 

I’m going to finish with this absolute stunner of an image, which combines two NavCam (Navigation camera) mosaics of the same scene, one taken in the morning and one in the afternoon. They were combined to show different landscape features that are highlighted as the sun illuminates some regions and casts others into shadow. After talking about the colours of Mars, you may be wondering what gives this image its striking blue and yellow palette. The NavCams on Curiosity only take pictures in black and white – colour was added to this image after the fact to highlight the lighting changes, with blue showing morning features, yellow showing evening features, and their combination showing just that – a combination of the two. This picture is looking back down Mount Sharp towards the crater rim in the distance, and it seems like a fitting image to close this blogpost on, looking back over the last great 10 years with Curiosity.

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. 

50th Anniversary of the Moon Landing Blog Post

This week, PVL Undergraduate Researcher Ariella Sapers reflects on a significant anniversary for space exploration: the 50th anniversary of the Apollo Moon landings. Above, a photo of a plaque like the one left on the lunar surface by Apollo 11. And yes, folks, that is Richard Nixon's signature on the bottom (to my knowledge the only politician whose name is written on a monument off the Earth) - it took the efforts of three different administrations to pull off this event.

By Ariella Sapers

With the 50th anniversary of the Moon landing just passing, I thought it was only appropriate to dedicate a blog all about the event and the celebrations that occurred here at York University!

On July 20th 1969, three brave men, Neil Armstrong, Edwin “Buzz’’ Aldrin, and Michael Collins took a leap of faith as part of NASA’s Apollo 11 lunar mission and headed to the moon. The Apollo Lunar Module, The Eagle, landed on the moon at 20:17 UTC in which Neil Armstrong became the first person to walk on the surface of the moon on July 21st at 02:56 UTC. With this walk, human beings had officially walked on the surface of a planetary body that wasn’t Earth. 

Water on Mars : A Brief History

RSL animated gif. (Image: NASA/JPL-Caltech/Univ. of Arizona)

Today, our newest MSc at PVL examines a large and well-known problem in planetary science: the water inventory of Mars and how we achieved the state of knowledge we now posses. Grappling with such big picture issues is as important for trainees as is the fine details of their own research.

By Brittney Cooper

The internet was recently abuzz with the latest results from the Mars Advanced Radar for Sub-Surface and Ionosphere Sounding (MARSIS) instrument, as it returned evidence for a sub-surface lake near Mars’ south pole. Of course, that’s not how a lot of us saw it communicated in the news and on social media. It can be incredibly hard to distill intricate and niche scientific findings for the public’s palate, and often you see media outlets striving less to find that balance in favour of simply slapping on a sensationalist title and making sweeping assumptions.

A misleading headline that once again reared its ugly head in many publications was the age-old classic “Water Discovered on Mars!”. The important distinction with this newest discovery is that the water is “liquid”, and while making that distinction may seem like a small oversight, it makes a big difference when considering the geologic, atmospheric, and astro-biological ramifications. Furthermore, water has been known to exist on Mars in both gaseous and solid states  since the 1970s, and in 2015 scientists also claimed to have found salty liquid water on Mars’ surface in the form of recurring slope lineae (see photo above).

Ice on Mercury and the Moon: Why So Different?

 

 A comparison of the poles of Mercury and the Moon illustrates similarities and differences that PVL PhD Candidate Jake Kloos explores in this blog post. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/National Astronomy and Ionosphere Center, Arecibo Observatory.

By Jake Kloos

The research I am conducting for my PhD pertains to the polar regions of the Moon, which have been active regions of study within the planetary science community for over half a century. For a variety of reasons, interest in the lunar polar regions is centered around the presence of volatile compounds, principally water ice. Ice deposits have been detected within permanently shadowed regions (PSRs), which are regions within impact craters near the poles that are permanently shielded from the Sun. Due to the lack of direct sunlight, temperatures within PSRs are extremely low, enabling them to trap, and potentially preserve, molecules such as water that are wandering about the surface. While ice has been detected within lunar PSRs, the concentrations that have been inferred from remote sensing observations appear to be unexpectedly low, at only a few percent by weight.

The low concentrations of ice found on the Moon is surprising given what we know about ice concentrations on the planet Mercury. Mercury and the Moon share certain key similarities that led many to predict that the two bodies would posses similar amounts of ice: both are considered “airless” bodies and host PSRs near the poles that exist within similar temperature regimes (although Mercury’s PSRs are slightly warmer). Despite this, ice appears to be abundant at the polar regions of Mercury, with inferred concentrations in the range of 50 to 100 % by weight. Moreover, radar data unambiguously show enhancements in nearly all of Mercury’s PSRs, whereas many PSR craters on the Moon lack similar radar enhancements. In fact, some of the lunar PSRs that do show radar enhancements are subject to debate, as some researchers feel that ice may not be the best explanation as to the cause of the enhanced signal. The large discrepancy in ice concentrations on the Moon and Mercury does raise the question: why?

The Observatory Blues

HD189733, a star with a particularly deep transit, as seen by the York Observatory 60 cm telescope. Giang, who joined us in May from McGill University, is obtaining a dataset for our Planets and Planetary Systems (PHYS 3070) students to use in class this fall.

By Tue Giang Nguyen

In preparation for the upcoming term, I was tasked with observing a transit of an exoplanet across a star in the constellation Vulpecula, known as the “little fox”. This is not my first time observing a transit and I cannot help but think that this would not be my last. Accompanied by Jake, a warm-hearted space enthusiast, we set out to take a series of images of what seems to be a tiny sliver of the vast darkened sky.

Forecasts leading up to the transit had not been promising; the hot humid air created a risk of thunderstorm. With the transit expected to last for two hours, the fear of poor visibility occurring during the transit loomed over my mind. My previous attempt at observing this particular transit had been foiled by rolling clouds high above. Whether it be frustration or sorrow, I can relate to the feeling of being inhibited by forces beyond our control, especially on the subject of astronomical observation.