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Alex Longo

Why Return to the Columbia Hills?

Posted by Alex Longo

23-10-2015 13:06 CDT

Topics: Mars 2020, Spirit, Mars Exploration Rovers, Mars

Where should NASA’s next Mars rover, the Mars 2020 sample caching mission, land? This question has come up in some form at virtually every Mars-related meeting this year. The powerful Mars Reconnaissance Orbiter (MRO), with its high-resolution imaging system and mapping spectrometer, has been busy gathering data on nearly 30 candidate landing sites. The choice has significance beyond 2020, because the Mars 2020 landing site will host a series of future sample return missions.

One site under consideration is the Columbia Hills. Located in Gusev Crater, the hills are named for the astronauts of the Space Shuttle Columbia STS-107 mission. The Mars Exploration Rover Spirit studied them from 2004 to 2011. Launched on what was supposed to be a three-month mission, Spirit dramatically exceeded its lifetime, making many scientific discoveries along the way and persevering through seemingly impossible odds. The historic mission became an inspiration to children worldwide, including me. I am 15 years old, and Spirit was the mission that inspired my love for space exploration. The rover, which seemed almost human to my generation, was an inspiration and a positive role model to us.

The Columbia Hills

NASA / JPL-Caltech / Cornell / ASU

The Columbia Hills
This enhanced false-color mosaic image from the Mars Exploration Rover Spirit panoramic camera shows the view acquired after the rover drove approximately 50.2 meters (165 feet) on the martian afternoon of sol 89 (April 3, 2004). The view shows the direction of the rover's future drive destination. In the distance are the eastern-lying "Columbia Hills." This image was assembled from images in the panoramic camera's near-infrared (750 nanometer), green (530 nanometer), and violet (432 nanometer) filters. The colors have been exaggerated to enhance the differences between cleaner and dustier rocks, and lighter and darker soils.

Why revisit a site that's been explored before? There have been only seven successful Mars landings, and the planet is huge; shouldn't Mars 2020 go to a novel site? But "go to a novel site" is not one of the Mars 2020 mission's science goals. Spirit went to the Columbia Hills to search for evidence that water influenced the geology of ancient Mars. The Mars 2020 mission and goals are different. Mars 2020 is being designed to investigate a geologically diverse and habitable environment, to search for direct evidence of ancient life, to assemble a cache of samples for a future mission to return to Earth, and to prepare for human exploration of Mars.

To accomplish the habitability investigation, Mars 2020 will need access to a variety of minerals formed in ancient aqueous environments.  The geologic diversity present in the tiny 3 by 5 kilometer footprint of the Columbia Hills is astounding: Clays, carbonate minerals, and sulfates all formed in either ancient, long-lasting lakes or in more recent, ephemeral lakes of varying salinity. Rock outcrops made out of nearly pure silica are evidence of an ancient hydrothermal system. Sampling the extensive volcanic basalts present will allow the age of the planet’s surface to be determined. This in turn could shed light on how the solar system formed.

New research by a team led by Dr. Steve Ruff also suggests that the Columbia Hills would be an excellent place to look for evidence of ancient life on Mars—the second major Mars 2020 mission objective. A hydrothermal system, such as that present in the Columbia Hills, has long been suggested as a niche where the molecules required for early life could have been assembled. The silica deposits discovered by Spirit on Mars bear a remarkable similarity to silica deposits found in the El Tatio hydrothermal field in Chile, an arid, Mars-like environment. The El Tatio outcrops have nodular shapes potentially associated with a biological origin, and they are teeming with microbial life. The ground truth from Spirit, coupled with a known analog environment on Earth, could make this hydrothermal system a good place to begin our dedicated search for past life on the surface of Mars. If we explore this ancient environment with a more modern instrument suite, could we answer the timeless question, “Are we alone in the universe?” It is possible.

Mars vs. Earth

NASA / JPL-Caltech / Cornell / ASU

Mars vs. Earth
The Columbia Hills as viewed by the Spirit rover (left) compared to the El Tatio hydrothermal field in Chile.

The Mars 2020 rover’s reason for being is to collect up to 30 diverse and exobiologically relevant samples to be returned to Earth with the objective of answering questions about astrobiology and planetary evolution. The compact and geologically rich Columbia Hills allow such a cache to be assembled from rocks and minerals identified for potential past habitability by Spirit. The Columbia Hills also meet the objectives for a Mars 2020 landing site because they are safe. The landing site is free of large obstructions and has a known topography, allowing the rover’s time to be spent doing science immediately rather than driving to distant regions of interest.

The Columbia Hills also satisfy the fourth Mars 2020 science goal—to prepare for human exploration—with its extensive geologic diversity. There is a unique opportunity provided by having access to the defunct Spirit rover. By imaging Spirit on the surface, we would, as suggested by Dr. Jim Rice, learn something important about how hardware ages in the Martian environment. The last thing we would want once a Mars base is built is for a critical component to fail, leaving the astronauts stranded. By imaging Spirit, we can learn which components of a machine survive the test of time on Mars, and which do not. 

The Columbia Hills feature a safe landing site with the potential for satisfying the highest-priority objective in the decadal survey, an extremely diverse geologic history, a potential abode for past life within an ancient hydrothermal system, and a unique opportunity to prepare for human exploration by understanding how hardware ages in the Martian environment. Perhaps the question is not “Why return to the Columbia Hills?” but “Why not?”


NASA / JPL-Caltech / MSSS

This picture of a crater resembling a "happy face" was taken in January 2008, by the Mars Reconnaissance Orbiter's Context Camera (CTX). The unnamed crater is about 3 kilometers across.
See other posts from October 2015


Or read more blog entries about: Mars 2020, Spirit, Mars Exploration Rovers, Mars


Hephaestus: 10/24/2015 03:43 CDT

Alex, congratulations on this blog entry. I read dozens of articles a day by professional journalists that aren't this well written. Your points are clear and considered and your style and grammar are both excellent. Whether you choose a technical or writing career, you're going to go far. Thanks for sharing this with us.

doc: 10/24/2015 07:08 CDT

Great post Alex. >Perhaps the question is not “Why return to the Columbia Hills?” but “Why not?” Mars is big. Seems like a crime to visit the same spot twice and ignore the RSLs or many other interesting landings sites at this point. It will also draw a huge amount of public criticism: "why are we spending $X billion to go to the same place on Mars again?".

Paul McCarthy: 10/25/2015 12:55 CDT

I agree with Hephaestus re clarity, style and grammar. Throw in comprehensive and up-to-date familiarity with the science and with the relevant vocabulary, plus wondeful stylistic flourishes. Amazing. Surely not written solely by a 15-year-old.

Torbjörn Larsson: 10/25/2015 10:39 CDT

The 2nd landing site workshop for the 2020 Mars rover mission [ ] had a very clear favorite, Jezero crater. [ ] As opposed to the 2011 Mars rover, this time it isn't a close call in the beginning rounds. And one can understand why, the Jezero paleolake sample a wide variety of minerals uphill, the landing zone is am organics preservation burial area, it was a longstanding near neutral pH lake and it is a premier target for manned landings. If it is chosen it isn't a loss, it too will sample hydrothermal units and likely then including silica producing alkaline such. [ ] As interested in astrobiology it is unlikely I could be more excited about a martian landing site! The article raises a good question, should we return to earlier landing sites and if not why not? I don't know the answer to that but I note that with the 2020 rover it means sampling the same environment 3 or 4 times. The followup sample collection mission and possibly even a separate return-to-orbit mission has to enter the same area. The 2020 rover mission doesn't seem to be the best mission to start doing return missions with.

MattSidor: 10/25/2015 07:14 CDT

I second Hephaestus, this was a great piece. I hope the next time we read about the 2020 recovery mission, it's written by you again -- and this time you're ON the rover team helping to make the new discoveries.

JulieRuble: 10/25/2015 09:30 CDT

Paul, that just goes to show you that you don't know THIS 15-year-old. But I do, and I'm not even a little bit surprised at how eloquent and thoughtful this post is :) Congratulations, Alex, on a well-written argument.

StarPolisher: 10/26/2015 10:05 CDT

If you read Alex's biography, you will find that he is indeed a capable and knowledgeable young man in his own right. It is phenomenal that the work of NASA has produced the inspiration and the collective knowledge that allows our children to soar. Dream big, Alex!

RakeYohn : 10/26/2015 06:37 CDT

Great article Alex, and very well written. You make a great case for the Colombia Hills. They should let you defend your case to your peers...

jpldoc: 10/26/2015 08:12 CDT

As a soon to be retiring and rather weathered scientist, I find it inspiring that there are young, intelligent and passionate people like Alex out there. This society, NASA and other organizations can still inspire and should seek the input of such remarkable future contributors. I would highly recommend the planetary society podcast to you and your peers Alex. It will prove to be a further source of inspiration. I look forward to following what looks to be a promising future.

Mewo: 10/27/2015 09:19 CDT

Mars's southern hemisphere has been rather dismally neglected. Hellas Planitia, for instance, would make a great target for exploration. Its low elevation means it was likely a huge inland sea at some point. Is there some technical reason why putting a rover there would be impractical?

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