MRO and Water on Mars

This is a significant development, as it appears to confirm that water — albeit briny — is flowing today on the surface of Mars.

– John Grunsfeld, associate administrator of NASA’s Science Mission Directorate

So, the big news from Mars that everyone’s talking about – so big that we’ve even heard about it here on simulated Mars – is: NASA confirmed evidence of liquid water flowing on Mars.  As it happens, I have a personal connection with this news, and would love to tell you the story…

…but first, we need to talk about NASA’s missions to Mars.

NASA currently has five robotic missions exploring the red planet: two rovers traversing the surface and three orbiters flying overhead.  The rovers, Opportunity and Curiosity, are operated from the Jet Propulsion Laboratory in Pasadena, California, but the operations of the three orbiters are contracted to Lockheed Martin Space Systems Company.  These orbiters, as well as the Spitzer Space Telescope and Juno, are controlled from a single control room, the Mission Support Area (MSA) in Littleton, Colorado.  They are:

• Mars Odyssey – Odyssey is currently the oldest orbiter still active around Mars, and holds the record for the longest mission ever to operate there.  The spacecraft launched in 2001…fans of Arthur C. Clarke might note the significance of the spacecraft’s name.
• Mars Atmosphere and Volatile EvolutioN – MAVEN, which launched in November of 2013 and arrived at Mars just over a year ago, is NASA’s newest Mars orbiter.  It studies the atmosphere of Mars, using a highly elliptical orbit that allows it to take shallow dives into the upper layers.
• Mars Reconnaissance Orbiter – Launched in 2005, MRO returns data at near-broadband speeds. Over the last decade, MRO has returned more data than all other users of the Deep Space Network combined.  This is the spacecraft that discovered flowing water on Mars, so let’s talk more about it.

Artist’s concept of the Mars Reconnaissance Orbiter. Image courtesy NASA.

As I mentioned, MRO returns massive amounts of science data from Mars. In November 2013, it surpassed 200 terabits of pure science data, and is still producing even more.  All of these data are measured and collected by a suite of six science instruments:

• Mars Climate Sounder (MCS) – MCS, built by JPL, is a nine-channel spectrometer used to measure the Martian atmosphere, in order to study the climate of Mars and obtain daily global weather maps.
• Shallow Subsurface Radar (SHARAD) – SHARAD is an instrument provided by the Agenzia Spaziale Italiana.  It uses radar waves to study the structure underneath the rock and ice layers of the planet’s surface.  Depending on the wavelength used, SHARAD’s radar waves can penetrate anywhere from from 7m to 1km under the surface.
• Mars Color Imager (MARCI) – MARCI is a low-resolution color camera provided by Malin Space Science Systems.  Its images are used to study daily, seasonal, and yearly climate variations.
• Context Camera (CTX) – CTX, like MARCI, is also provided by Malin Space Science Systems, and the two are frequently commanded together.  It’s a low-resolution grayscale camera.  Although it can provide large-area mosaics of the planet’s surface, it was primarily designed to provide context images for the targets of the next instruments on the list: HiRISE and CRISM.
• High-Resolution Imaging Science Experiment (HiRISE) – HiRISE, built by Ball Aerospace & Technologies and run by the University of Arizona, is MRO’s high-resolution imager.  It’s the largest telescope ever flown on a deep-space planetary mission, and is powerful enough to resolve objects as small as a beach ball on the Martian surface.  This is the instrument that originally observed evidence of flowing water on Mars.
• Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) – CRISM, provided by John Hopkins University Applied Physics Laboratory, is a spectrometer used to identify and map the surface mineralogy of the planet. This is the instrument that made the most recent findings.

As I’d mentioned before, MRO is flown mostly from the MSA (one day a week, a second team at JPL flies the spacecraft).  This is where I worked prior to joining HI-SEAS IV.  My main job there was as a Pointing Control Subsystem engineer for Spitzer.  However, many of the engineers in the MSA have multiple jobs, either working in the same discipline for several spacecraft, working in multiple disciplines, or working on the development of new spacecraft.  I was no exception: I spent roughly a quarter of my time as a Real-Time Operator, or “ACE”.

“ACE” is one of the coolest jobs – and job titles – I’ve ever had.  The job of an ACE is to communicate directly with the spacecraft, sending the commands built by the subsystems and systems teams.  We’re considered a shared resource, and all of our spacecraft use a common ground commanding system.  As a result, we’re trained to command almost all of the spacecraft in the MSA (the exception is Spitzer, which is commanded by a dedicated ACE team at JPL).  All of those instruments and all of the data being collected by MRO mean that it’s one of our most heavily-commanded spacecraft.  As a result, I’ve spent more time on console in my ACE role and sent more commands for MRO than any other spacecraft.

So, flashback to Spring of 2011.  I’d just received my certification for Spitzer Pointing Control, and was in the middle of my ACE training.  I was in Phase 3, which meant that I was allowed to send commands to a spacecraft as long as I was supervised by a certified ACE.  During a commanding window on MRO, I was handed an uplink summary labelled “Horowitz Crater Special Observation for HiRISE”.  Being just a trainee, I didn’t realize it was anything out of the ordinary, and dutifully sent the command to the spacecraft as normal.  After the command cleared the dish, the MRO systems engineer on console, Mykal Lefevre, told me, “Congratulations, you just took a photo of water on Mars!”

…wait, I just did what?

It turns out, I’d just commanded some of the last HiRISE images in a science campaign to track growing streaks seen on the slopes on Mars.  By that point in the campaign, the scientists already had a pretty good idea that they were looking at water.  I’d just done one of the coolest things I’ve ever done in my career, and I hadn’t even known I was doing it!

…and I couldn’t tell anyone about it!

You see, science data collected by NASA spacecraft isn’t made available to the public immediately.  Most of it is placed under embargo for a period of several months, sometimes up to a year or more.  This gives the principal investigators time to evaluate their data and publish their papers.  If these embargoes weren’t in place, other scientists would have free access to the principal investigators’ hard-earned data straight away.  So the data embargo makes sense, but it also means that I couldn’t tell anyone outside the MSA about what I’d just done, including my friends and family.

Subsurface flows on the slopes of Newton Crater, imaged by HiRISE. Image courtesy NASA/JPL-Caltech/Univ. of Arizona

The big news was finally released in a NASA press release in August of that year.  The HiRISE photos and the measured climate conditions suggested that the streaks were caused by water ice under the surface melting and flowing downhill.  As the temperature was slightly below freezing, the most likely explanation for the fact that the water was able to exist in liquid form was that it was briny water.  Salt lowers the freezing point of water (that’s why we sprinkle salt on icy sidewalks).  These measurements – the evolving streaks, the measured temperature – effectively eliminated the chances that some other volatile material was causing these observations.

In other words, in 2011, while NASA had a pretty good idea of what they were seeing, they weren’t completely sure…until now. That’s what this recent news is all about.  In the last four years, MRO has flown over the sites where the streaks were previously observed and used CRISM to measure the composition of the materials at these sites.  The CRISM spectra confirm what scientists suspected before: the streaks are indeed due to subsurface brine flows.

Does this give strong evidence that life may currently exist on or near the surface of Mars?  Not exactly.  While it’s not entirely impossible, the water may be too salty to support life.  But what this does indicate is a certain abundance of water on Mars.

For those of us interested in the human exploration of Mars, this means that if astronauts take along equipment to remove the salt, they may have a supply of water already waiting for them when they arrive. For me, it’s a personal point of pride to see work I’ve performed directly contributing to our knowledge of the Solar System.