This week we've got a double bill here at PVL. In dueling articles, two of our Mars Science Laboratory Collaborators, Brittney Cooper (at left in the image above) and Charissa Campbell (at center) reflect on Curiosity's 2000th martian day (or sol) on Mars. The third person pictured above is Christina Smith, PVL Postdoctoral fellow and fellow MSL Collaborator and ESTLK. Charissa kicks us off with a description of the day and is followed up by Brittney's article about how that beautiful image in the newspaper gets produced.
by Charissa Campbell
As of March 22, Curiosity celebrated her 2000th day on Mars. I was lucky enough to be on operations during this monumental moment as some members of our research group are a part of the Environmental (ENV) Science Theme Group (STG) for Curiosity. This STG is responsible for the environmental side of operations, which includes advocating and planning observations beneficial to our research such as atmospheric movies. The official name for our role is the Environmental Science Theme Lead and Keeper of the Plan, or in a much manageable form, ESTLK.
There are several key items we must consider when planning for the rover. One example is that we are not the only STG, the other being Geology (GEO) that studies various geological formation in Gale Crater. If I could, I would plan 1 hour long atmospheric movies to watch Martian clouds all day, however, we must play nice with the other kids on the playground. To ensure we don’t overuse the rover, we must work together so observations don’t overlap. There are four main science objectives that Curiosity must meet during her lifetime to fulfill the overall goal of assessing past and present habitable environments at Gale crater:
1. Assess the biological potential of a target
2. Characterize the geology of the landing region
3. Investigate planetary processes by assessing long timescale atmospheric evolution
4. Characterize the broad spectrum of surface radiation.
The STGs are responsible for making sure these science objectives are met by planning out the observations needed on a sol-to-sol basis.
Another obstacle we face with planning is that Mars is notoriously colder than Earth. Even though this might be similar to a typical Canadian winter, it still can cause problems for the rover. I’m sure it isn’t always a problem here in Ontario, but as a kid I always remember having to plug in our car at night to make sure it would start the next day. On extremely cold nights, this was a needed feature in Alberta or you’d be taking transit to work the following morning. By putting this into context, at Curiosity’s location the average temperature can range from -60° to 0°C between night and midday. However, Curiosity isn’t lucky enough to have plug-ins to charge for the following sol. Instead, the STGs must manage our observations to allow Curiosity to sleep whenever possible. That way she can charge and always be at a high enough energy threshold to still produce science the next sol. That sounds a little scary when written like that, but that is the nature of planning for a rover on another planet. We are currently in the last few weeks of winter in the Southern hemisphere on Mars, so this was always in the back of an ESTLK’s mind.
These winter months also coincide with the cloudy season on Mars. During these months, we are at the farthest point from the Sun, so the atmosphere is cool enough for ice crystals to hold onto dust particles and form clouds. Analyzing these clouds is the underlying theme for our research so the more atmospheric movies we can get during this time, the more beneficial. We also must consider that this season only occurs once every Martian year, where one Martian year is approximately two Earth years. Therefore, we must take advantage of this time by advocating for more atmospheric movies.
For sol 2000, we were aiming our drive to get to another stop in the Vera Rubin Ridge (VRR) Campaign, while also getting contact science on the way. Most of the science we do is part of the campaign to better understand the geology on our traverse towards Mount Sharp. The unique part of the atmospheric movies we use is that they are not necessarily dependent on where we are in the crater but more dependent on the time of sol. This allows us to plan these observations whenever there is room for one. Luckily, I was able to get one in the late morning to help characterize clouds. My goal for sol 2000 planning was to get an atmospheric movie in, just to have one on this historic sol, and look to our cadence to understand what other observations we need.
When planning, we must adhere to the cadence for our STG. It is a timeline to keep track of what observations need to be taken and to make a note of what goes through the plan. Most observations characterize the atmosphere and environmental properties of Gale Crater, so they must be taken at a reasonable schedule. For example, the atmospheric movies should be taken once every 2-3 sols to be able to characterize cloud activity throughout an entire Martian year. Therefore, we have them in 2-3 sol frequency in our cadence so an ESTLK will know when one should be planned. If you are interested in learning more about planning and mission operations for Curiosity, check out this link: https://msl-scicorner.jpl.nasa.gov/scienceoperations/
All-in-all planning went smoothly and the rover was healthy. It was my great pleasure to represent the ENV team for sol 2000!