Vivian Sun: Mars Explorer

 

Vivian Sun spends most of her time investigating certain minerals – the building blocks of rocks – to gather hints about when and where water once flowed on Mars. Between her stints in the lab and poring over images from the Red Planet, though, she helps out with science planning for the Mars rover Curiosity. How did she get a cool job like that? Read on to find out.

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Vivian studying the surface of Mars!

What is your role in space exploration?

My current research focuses on identifying hydrated minerals and characterizing past (possibly) habitable environments on Mars.

Editor’s note: Minerals are the building blocks of rocks – if you think of rocks as books, then minerals are the words. “Hydrated” minerals contain water locked away inside of them!

This involves looking at a lot of spectra and images returned from Mars as well as measuring spectra of minerals in the lab so that we can better evaluate the orbital data.

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A fresh impact crater on Mars. [Courtesy NASA/JPL]
My favorite project so far has been looking at clays found at central peaks of impact craters. Most clays are thought to have formed during the Noachian period (>3.7 billion years ago), suggesting that the most habitable conditions on Mars existed a long time ago. Some of the evidence supporting this paradigm are clays found at central peaks, which are assumed to excavate deep, old materials. Our work used CRISM and HiRISE data to determine the origin of clays at 630 central peaks. We found that although most clays are indeed excavated and indicate older habitable periods, a third of central peak clays could have formed (e.g., in impact melt) or been transported (by wind or water) into the crater after the impact event. Many of these craters are Hesperian or Amazonian-aged, suggesting that habitable conditions could have existed more recently than previously thought.

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An example of the images Vivian uses to identify minerals on Mars. By using two photographs captured with slightly different lighting, 3-D models of the terrain can be developed. Spectra then help scientists determine what minerals are present. [Courtesy: V. Sun]
My thesis work focuses on opaline silica, which is an interesting hydrated mineral because it can be found as different phases (opal-A, opal-CT, opal-C) depending on how much it has been altered by water. Currently I am developing spectral parameters to distinguish between these different opal types so that we can identify them from orbit. I’m also measuring opals under simulated Mars atmospheric conditions so that we can better compare our lab data to the orbital data. We find that different types of opals do exist on Mars when we apply these laboratory results to CRISM detections, but it will take more morphologic analyses of using high-resolution images to determine why that is the case.

Why is it important to understand where opaline silica is on Mars?

Identifying the type of (opaline) silica tells us how long water may have lasted in that environment, which is an important factor to consider for habitability. For example an environment that was only able to form opal-A might not have been able to sustain water long enough for life to develop, whereas an environment with opal-CT might have been more habitable, with longer-lived water.

What’s your role in Curiosity’s mission?

Like most student collaborators on the mission, I usually act as the Documentarian (Doc) or Keeper of the Plan (KOP).

A typical planning day is composed of many meetings and involves a lot of coordination between the science, instrument, and engineering groups. At the beginning of the day the science groups (Geology and Environmental) make plans of their desired science activities for the day. The science plans are submitted to the Science Planner, who integrates all of the engineering and science activities into a single plan.

The team then walks through this collated plan at the SOWG (Science Operations Working Group) meeting to finalize the plan and ensure that the planned activities are feasible and meet rover mobility and data/power restrictions. The last major meeting is to get a head start planning the next day’s activities. The Long Term Planner (LTP) helps guide the discussion by laying out our longer-term goals so we know how to pace activities and manage data/resources.

These are the daily planning meetings, but there is also a lot of work that happens in the background. Science team members are constantly analyzing newly received data and presenting them at Science Discussions so that the team can plan appropriate activities in the short-term and long-term.

As KOP, I assist the Geology group in assembling the day’s plan of our desired science activities. As the group discusses and finalizes which targets we’d like measurements on, which instruments to use, what the optimal time of observation is, etc., I gather these inputs into the Geo plan. At the last planning meeting, I play a similar role in putting together a basic plan for the next day.

As Doc, I take notes at the SOWG meeting, where the entire plan is walked through and finalized by the science, instruments, and engineering groups. Doc reports provide a short summary of each day’s plan and keep a record of the team’s planning decisions.

Cool! How did you get that job?

My advisor Ralph Milliken is a participating scientist on the mission and it’s thanks to his involvement that I am able to take part in rover operations. I’m very grateful for this opportunity and it’s been a great experience to see how scientific ideas get translated into actual rover activities.

What piqued your interest in space exploration? Was there a certain person or event that inspired you?

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The Spirit rover captured this image of a dust devil racing across the surface of Mars. [NASA/JPL]
There wasn’t a specific moment or event. I was interested in astronomy in high school, but quickly found out in college that I did not like the physics that entailed. But in my freshman year I took the introductory geology/planetary course sequence and really liked how you could build a history of Earth and other planets by looking at the rock record. During my undergraduate summers, I was lucky enough to take part in several research projects that guided my interests in planetary science. In my last year I worked on a Martian dust devil and wind streak project with Leslie Tamppari at JPL, and I loved it so much that I decided to apply to graduate school to study Mars!

 

If you got to land anywhere on Mars, where would you go? Why?

As much as I would love to land somewhere that I’ve done a lot of research on, I would have to pick Mawrth Vallis or Nili Fossae. Almost all categories of hydrated minerals that have been identified on Mars can be found in these regions. Most aqueous activity on Mars is thought to be restricted to the Noachian period, but there’s a lot of debate about whether that period was “warm and wet” or “cold and dry” and how quickly climatic changes occurred. Maybe going to one of these ancient sites can help unravel some of these complexities since they have such diverse mineralogic exposures. So much of what we’ve learned at Gale Crater [Ed: rover Curiosity’s landing site] at the rover-scale is unobservable from orbit due to dust cover and coarse spatial resolution. If we can already see so much at Mawrth and Nili from orbit, I imagine the view on the ground must be spectacular.

 

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Mawrth Vallis on Mars, where minerals suggestive of ancient water linger on the surface. [Courtesy: NASA/JPL]

The Apollo moon landings were a defining moment that inspired an entire generation of scientists and engineers. What do you think was, or will be, the defining space exploration milestone of our generation?

I definitely hope it will be landing a human on another terrestrial planet, hopefully Mars! That would be an incredible technological accomplishment and would open up so many possibilities for the in situ science we could do beyond rover capabilities. Sample return would also be amazing, particularly from a body with an atmosphere, like Mars. We’ve had successful sample return missions in the past, but making these types of missions more “routine” would help a lot with groundtruthing our orbital observations.

What advice would you give kids who also want to study Mars?

Always try to be learning something new. Mars, in particular, has a wealth of datasets from multiple orbiters, rovers, and landers that are available for anyone to explore. Of course these data can also (and should) be correlated with terrestrial analog, laboratory, or theoretical modeling work. It’s often a combination of observations across multiple datasets that leads to exciting discoveries, and nowadays it is advantageous to be proficient in multiple areas of study. Along the same lines, don’t be afraid to dabble in projects that you don’t think may necessarily pay off. My thesis work was motivated by a chance observation at a crater that I was exploring in between projects.

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