Mars, Like Earth, is not a Simple Planet to Understand

This confusion was not the result of the presenters speaking a week before they had planned. Rather, it was the result of several years of data from Mars colliding with old models and assumptions of how the planet was supposed to behave. Paradigm revision was happening – almost in real time.

° Replay the entire press conference (RealVideo), Discovery.com

The substance of this press conference was a number of features that have been found on Mars – features that can be best explained by the presence of liquid water. What is confounding is the fact that these features are found in some of the coldest regions of Mars – places where prevailing Mars models show permafrost (if present) frozen solid for several kilometers.

The co-author of this research article, Ken Edgett, from Malin Space Science Systems (MSSS), said several times that he was “dragged kicking and screaming” to the conclusion that liquid water was behind the phenomena they had discovered. Edgett’s co-author Michael Malin, also of MSSS, and the other participants all voiced similar stories of being brought reluctantly to the conclusion that water was at work on Mars.

The press conference was surprisingly smooth and well-organized despite the fact that until just a day or so ago everyone involved had expected to have another week to prepare. The press conference was moved up by NASA and the journal Science after news reports containing partially correct/partially incorrect information began to take on a life of their own. One of the participants noted that the “science fiction” had started to eclipse the actual facts contained within their paper.

Not to have gone ahead and released the paper and allow the investigators to speak for themselves would have been an error. Luckily, NASA and Science met and decided to do the right thing.

According to NASA’s Associate Administrator for Space Science Ed Weiler, Malin had approached NASA about a month ago with the news that he had submitted a paper to Science magazine with some rather exciting data. NASA had sought to work to honor Science magazine’s embargo. That worked well until a few days ago. As Michael Malin said “we’re paying people back” who had paid for this research by releasing this information as soon as they could.

Weiler broadly described results as showing the presence of water on Mars not hundreds of millions or billions of years ago, but rather, within thousands of years – perhaps even more recent. He added that if indeed there is active, liquid water near the surface of Mars, that this could have profound implications for the prospect of life on Mars. Placing this in context, Weiler noted that we orbit one star in a galaxy of billions of stars, in a universe of billions of galaxies. If the first place off of our Earth we look in depth has evidence of life this would have profound implications for what might be found elsewhere.

The images and data presented today were the culmination of a year of data collection one that began only after the Mars Global Surveyor’s (MGS) mission got a start – one year late. The images were taken by the Mars Orbiter Camera (MOC) after the MGS had reached its circular mapping orbit. What they found was not what they were looking for leaving the researchers “surprised and confused”, by what they saw, according to Malin.

Malin said “we had a hint of these features 2 years ago – but at 20 meters per pixel it was not science, just speculation.” As they collected more and clearer images, the broader picture became clearer. What they saw ran contrary to prevailing models of Mars which suggested that any active water deposits, if present, would be found at or near the equator where solar heating was greatest and that they would point toward the equator i.e. at the sun.

The features they found were landslides where material has moved down a slope creating an “alcove” at the top, a “channel” along the way down, and forming an “apron” of debris at the bottom. These formations were found to occur mostly in clusters, with larger groupings in the southern highlands. On Earth, such features would likely be the result of water percolating through the ground and causing material to move once the water emerged out of a hill or cliff. Such features are often called “weeping layers” and are found in many places including the Colorado plateau.

According to Malin, the features they found are rare and only appear in 200 – 250 of the 65,000 images taken thus far by MGS. Most of the features have been found south of 30 degrees South or north of 30 degrees North. Moreover, they are oriented in a poleward direction – facing away from the sun. This was a bit confusing. The features were in the coldest – not the warmest portions of Mars and they were oriented away, not towards, the direction of the sun – places where you’d least expect liquid water.

The location and orientation of the features were not the only things that drew attention – and caused some confusion. These features were characteristic of rather young formations. One of the standard ways of dating features on Mars and other planets is counting the number and size of craters. The more craters you see, the older something is. None of these features had craters. Ken Edgett showed an image of one feature where a debris apron came down a crater wall and covered a dune field. Dune fields are rather temporal features forming and changing rather rapidly. As such, the apron itself must be rather young – certainly younger than the dunes it was laid down on top of – dunes that are rather young themselves.

Edgett also showed debris aprons stretching across a series of polygonal features. On Earth, similarly shaped polygons have been found in arctic and Antarctic locations that are the result of repeated freeze/thaw cycles of water in the ground.

Another location showed evidence of rocks where the dust has been cleaned off. On Mars, dust is constantly being deposited. Structures were the dust has yet to really accumulate are indicative of structures that may be only a few years old.

According to Edgett, the features clearly have a relationship to sunlight – one that is backward to what they had thought. He showed a diagram that represented what the team thought was happening. Material emerges from a specific layer of rock within a few hundred meters of the surface and flows out onto the sloping wall of a crater. As the material moves down the slop, material is loosened from above and also falls down. The sun meanwhile, is hitting the opposite slope.

Both sides of the crater have the same layer – but only the darker, colder side has these features. Edgett hypothesized that on the darker side, the water comes out, freezes, builds a dam of sorts, pressure mounts, the dam bursts, and material rushes outward and downward creating an apron of debris once it stops.

On the sunlight slope, Edgett suggested that water comes out, hits the low atmospheric pressure and explosively sublimates into a very cold steam. The result is little or no landslides – or alcove and channel formation.

In addressing the issue of how they might further pin down the age of these features and frequency with which the form and change, Edgett said enthusiastically “keep taking pictures in these areas. If it changes -WOW, we’ll be back!”

Michael Carr, from the US Geological Survey in Menlo Park, then spoke. Carr was asked to review the work as an outside observer. He described himself as worrying about water on Mars for 30 years. He said that these results are “exciting” – in fact, according to Carr, “the images are very compelling – as is the evidence that liquid water is responsible for them”.

Carr’s concern was that these things were showing up in the places where you’d least expect liquid water to be. The average temperature in these regions is -70C to -100C. In these locations at high latitudes the ground should be frozen solid. Yet here these features are.

According to Carr “Carl Sagan used to warn us about terrestrial chauvinism. We tend to interpret photos in light of our experience on Earth. Things are different on Mars.”

Suggesting that there might be alternative mechanisms that explain these features, Carr mentioned clathrates. Clathrates are formed from water and CO2 under pressure at low temperatures. A number of researchers suspect that they are present on Mars. Clathrates are stable underground while under pressure but not on the surface. Carr suggested that sudden exposure of clathrate deposits could unleash gas eruptions similar in effect to volcanism resulting in these features.

Carr concluded his comments be repeating his concern with our ability to understand what we are seeing by noting that “there is still a gap between our observations and interpretations of Mars.”

Bruce Jakosky from the Astrobiology program at the University of Colorado in Boulder also spoke as an outside reviewer. Jakosky focused upon the astrobiological aspects of these discoveries. Noting that “we did not expect to find this”, he went on to describe these confusing discoveries as an opportunity to revisit models of how water might behave on Mars. Jakosky referenced Carr’s clathrate model and then suggested one of his own – a mechanism akin to letting a trickle of water flow though your pipe in the winter to keep them from freezing. Perhaps allowing water to flow through regions of permafrost might allow some portion to remain liquid for significant periods of time.

Jakosky echoed Carr’s reference to Carl Sagan’s admonition about terrestrial chauvinism saying that “Mars is not the simpler than Earth planet that we have been treating it as. Mars is just as complicated as Earth.”

Moving to the topic of life, Jakosky suggested thinking about the requirements that would believed upon the Martian environment to support the origin and continued existence of life – liquid water, the specific chemical elements to make (assemble) life, and some sort of energy source – be it solar or geochemical.

Jakosky noted that “on Earth, every where you find water below boiling point, you find life.” Referring to these new discoveries, he said “this is the smoking gun – there is liquid water and Mars meets all the requirements for supporting life”. He added that assessing this water for analysis would now be much more straightforward since it is now closer to the surface than previously thought.

Jim Garvin, the Mars Exploration Program Scientist at NASA Headquarters, spoke of the “follow the water approach” recently adopted by NASA to guide its Mars exploration program. Referencing all that had been said thus far, he said that these discoveries “filled in a missing piece of Mars’ hydrologic cycle”. He suggested that future missions would be structured so as to focus further on this hypothesis. He closed by saying that “the story is just unfolding. As we follow the water we need to understand that water is more available to our robotic exploration tools than we had previously thought.”

Ed Weiler then sought to summarize the previous presentations as they applied to upcoming missions. He said “we have to make a decision on the 2003 missions rather soon.” NASA intends to fly two missions. One is an orbiter, the other is a lander with a rover. The schedule for these missions is rather tight since they are only 3 years from launch.

According to Weiler, NASA’s “Mars Czar”, Scott Hubbard, will make recommendations to Weiler in July and they will be announced at a press conference in the 3rd week of July. Weiler said that NASA is now restructuring NASA’s Mars overall exploration Program. In so doing, he said that NASA would be looking at developing a long term plan that will look ahead 20 years. Weiler said he hoped to announce that plan in the Fall of 2000.

When asked about the prospects for human missions to Mars, Weiler said that much more needs to be done in terms of human physiology and other issues before humans can go to Mars. He also hinted at the benefits of in situ propellant generation and the benefits that this would have upon the materials that would need to be brought to Mars from Earth.

Weiler closed by saying that “Mars is not that small little red dot I saw in my telescope as an amateur astronomer. Mars has the same surface area as the Earth It is a very very large place. Before picking a landing spot, we need to make sure it is the right one.”

In describing the work to come in terms of assuring eventual human missions, Weiler said that it might be prudent to have a more robust planetary communications infrastructure – logistics too. As for lading precision, he cited the need for smart intelligent landing systems. “We want to be able to land robots in very specific places – and need to be able to do this before we send humans”. To guide spacecraft in, he suggested that we might need a Martian GPS system of sorts. “We have to teach computers to be like cruise missiles on Mars as they home in.”

When asking a question, I suggested to Weiler and Jakosky that NASA’s ‘follow the water” strategy took them only indirectly to finding possible past or present life on Mars. I asked them when NASA would move forward from searching for indirect evidence for life to direct evidence – and how these recent discoveries might affect such decisions.

Weiler responded that NASA’s ‘old architecture’ for Mars was to spend a billion dollars, go to Mars, land in one or two places, and bring samples back. Any further work would have been simply to go and bring more rocks back.

Weiler said that he wants to try and broaden our thinking as all Mars plans are revisited. He said that there was “no long term vision beyond sample return” in the current approach. He said that he is trying to open the box – and to get people to think a little more broadly. Specifically, he asked – can we do astrobiolgy experiments on Mars in situ by miniaturizing spacecraft and putting them on Mars?”

Noting that “Mars is a diverse place” he chided the old approach of “putting a lot of assets in one place”. Instead. Weiler said that NASA needs to be looking to put instruments in a large number of locations. Specifically, in support of this plan, he spoke of a line item in the President’s budget – a few million dollars. He spoke of an interest of ding an NRA (NASA Research Announcement) to solicit the best proposals. [Editor’s comment: given the immensity of the task the $6 million in the proposed FY 2001 budget and the slight increase over the next few years is not all that will be required.]

Jakosky added that the search for life is very difficult. “We do not know what it is like on Mars” he said. ‘We can’t just go and say we’ll use this instrument to look for that aspect of life.” He said that we need to know more about the entire context of life against a Martian backdrop before we go off designing instruments.

In summary: the 1996 announcement regarding possible fossil organisms within the ALH 84001 Mars meteorite gave us tantalizing evidence that life might have existed on Mars billions of years ago. This discovery regarding liquid water near the surface of Mars provides tantalizing evidence that the conditions supportive of life could exist on Mars today.

Curiously, just as Mars provides a new, tantalizing reason to go visit, we find it harder to do the things it takes to get there – things we once did with ease.

We still have a lot to learn – and relearn – before we head back to Mars.

Related Links

° New Images Suggest Present-Day Sources of Liquid Water on Mars, NASA

° Evidence of Recent Groundwater Seepage and Surface Runoff on Mars, Science Magazine

° Malin Space Science Systems

Background Information

° The Whole Mars Catalog

° Mars Missions, SpaceRef Directory

° The Planet Mars, SpaceRef Directory

° NASA to Make Major Announcement Regarding Water on Mars, SpaceRef

° The Whole Mars Catalog

° Workshop To Examine NASA’s Mars Exploration Program, SpaceRef

° Two Mars Mission Reports Delivered to NASA; A Third to Follow

° NASA Releases Eighth-degree topographic shade maps of Mars

° A Feast for the Eyes: A Large Collection of Stunning High Resolution Views of Martian Polar Terrain has been Released

° NASA Releases Eighth-degree topographic shade maps of Mars

° Mars Exploration: AAAS Ponders: “Where do we go from here?”

° Nomad the Robot Finds a Meteorite in Antarctica

° Astrobiology Reports and Plans, SpaceRef Directory

° Workshops, Meetings, and Conferences, The Astrobiology Web

° Mars Deep Water Sounding Workshop, NASA ARC

° Mars Deep Drilling Workshop, Los Alamos National Laboratory