Wispy Clouds on Mars!

Normally I use this space to make some "witty" comments to ease you, our readers, into each article. But today I'm going to get out of the way because I just can't say it better than seasoned MSc student Charissa Campbell and her animations: "Here are the beautiful movies taken on sol 1758. On the left is the SHM which shows the Martian landscape with the wispy clouds above. The right is the ZM that is taken directly above the rover but still shows the similar wispy features as the SHM. They are both taken around 7:00 am."

 by Charissa Campbell

One of my roles on the Curiosity Science Team is to process the atmospheric movies taken by the rover. They consist of 8 sequential images of the sky above the rover. There are two kinds: Zenith Movie (ZM) and Supra-Horizon Movie (SHM). The only difference between these two observations is the angle of the camera with respect to the rover. The SHM is taken at an angle of 38.5° elevation, which is right above the crater rim, while the ZM is taken directly above the rover at an angle of 85°. 

Most of these movies are taken either in the early morning or afternoon as studies show that these two periods during the sol are when clouds most likely appear. In fact, there even is a season on Mars that exhibits more clouds than other times of the year. This is known as the Aphelion Cloud Belt (ACB) and starts in the late fall in the southern hemisphere, where Gale Crater is located. It is given this name because it peaks around the Aphelion of Mars; the furthest point that Mars will be in its orbit around the Sun. Clouds can be seen at other times of the Martian year. However, the ACB is a season that distinctively shows clouds. We even use this recurring season to plan atmospheric movies for Curiosity so that we can analyze these clouds in greater detail.

For me, every week is usually the same; I process the new movies that were acquired by the rover over the last few sols. In late July, I got to work on the last atmospheric movies before Curiosity entered conjunction – conjunction being the time when Mars is on the other side of the sun as viewed from the Earth. This event is notable as we are unable to communicate with the spacecraft or conduct operations due to solar radio interference. There were a few movies available including both SHMs and ZMs but most of the movies I was processing hardly showed clouds; if any at all. This is because we are not quite into the ACB season. 

All that changed when I arrived at the last batch of movies taken on sol 1758, part of an early morning observation that takes a SHM and then a ZM right afterwards. Since all the other movies had null clouds in them I expected the same for these ones but boy was I ever wrong. Sure enough, the SHM had the most beautiful cloud that I literally gasped as soon as I viewed the movie. I could not believe my eyes as they were so distinct and nothing like we have really seen before as they had such wispy features. Noting this movie, I immediately went to process the ZM as it should theoretically show the same features since the only difference is the camera pointing. I couldn’t have been happier as this movie also showed those wispy features and as a bonus, we now had two different angles at which to examine these clouds. 

Could this cloudy day on Mars continue? There was also another SHM taken the same sol around noon. However, this observation did not show any clouds. The absence of clouds here is not entirely surprising, as we already know that this time on Mars is usually cloudless. However, given how prominent the cloud features were in the early morning movies, I figured something might have shown up during this midday movie. This null movie is still important as it shows us that these clouds dissipate within a matter of hours. Another thing that is interesting about these movies is that they are taken right before the actual ACB starts. Therefore, we did not expect to see such unique features. However, maybe this set of movies indicates that the ACB season is starting a little early this year or that ACB clouds last longer at colder times of the day.

Knowing that I had these amazing movies from the rover, I immediately brought it to the attention of John and my colleagues who agreed with me on their spectacular features. He noted that the features shown are most likely wispy cirrus-like clouds that we would see here on Earth. Those type of clouds tend to occur at high altitudes and can be difficult for the human eye to observe in the sky. John suggested that I email other colleagues from the rover to share these movies and, a few weeks later, they were put out to the general public through the Mars Science Laboratory (MSL) website (https://mars.nasa.gov/news/2017/watch-martian-clouds-scoot-thanks-to-nasas-curiosity).

The response was quiet at first but then the press release was picked up by various scientific websites including Gizmodo and, my favourite, IFLScience (http://www.iflscience.com/space/check-out-this-awesome-footage-of-clouds-on-mars/). To be honest it was quite overwhelming for me at first as I am a very introverted person, however, I couldn’t help but share the stores a few times since my name did make it on to a scientific website. The experience has made me more grateful and excited to keep doing my research but I won’t boast anymore even though I am still living off of the high of having something published like this with my name also there. 

Hope you enjoyed the movies like I did!