Digging Wonderland

The soil has surface features similar to those found in areas of permafrost on Earth where the seasonal freezing and thawing produces a polygonal patchwork. Just as recent studies have equated other Martian features with Earth analogs, mission planners hoped that the polygons would be the right place to confirm the presence of water, at least in the form of ice.

Ever since the Viking lander missions in the mid-1970s produced mixed results concerning evidence of biological activity (see below), NASA’s follow-up to the “Is there life on Mars?” problem has focused on looking for water. Although not designed with any experiments similar to those carried out by Viking (which sought to detect metabolic processes), Phoenix is built to investigate the habitability of the Martian soil.

As per plan, for the last 60 days Phoenix has been digging and preparing to analyze the top layers of soil for water ice, organic chemicals, characteristics associated with periodic meltings, and other indicators of possible past or present environments suitable for microbial life.

Other meteorological investigations are also ongoing. Although they do not have the sparkle of soil and habitat sampling, an understanding of the dynamics of the Martian atmosphere is also important in piecing together the history of water on the planet. For the first time in interplanetary studies, for instance, a surface vehicle and an orbiter are coordinating both above and below observations of the same patch of sky. Not so long ago this could not be done even on Earth.

Nevertheless it is the search of the soil and water that draws our greatest attention.

Robotics

Phoenix’s main investigative tool is an extendable arm that ends with a scoop/scraper-rasp/drill apparatus. After collecting a sample of soil, the arm delivers it to one of two onboard robotic laboratories for chemical analysis. Each of these, TEGA (Thermal and Evolved Gas Analyzer) and MECA (Microscopy, Electrochemistry and Conductivity Analyzer), is capable of several different chemical investigations.

Working an area the controllers named “Wonderland,” so far the arm has scraped away a small trench about the size and depth of a shoebox lid (25 centimeters by 60 centimeters by 5 centimeters). This will be enlarged as experiments continue. The trench itself is informally called “Snow White.” Investigators selected these labels as a way to bring children greater accessibility to the mission. “This is Once-Upon-a-Time Land,” says principle investigator Peter Smith. “This is Wonderland because we wonder what’s under that polygon.”

With the extended funding, Smith outlined further plans for trenching during a late July news conference. We are looking for a “history of ice” he said, noting that the trough at the edge of the polygon structures will be the next study area. The two new areas will be called “Cupboard” (“because we wonder what’s in there”) and “Neverland.”

Water

The key to habitability is the presence of water. “It’s liquid water we are most interested in,” says Smith. The first indication of water ice was a hard, white layer uncovered by the thrusters during landing. Visible to the cameras on the robotic arm, the apparently icy area was unfortunately out of reach beneath the lander.

Subsequent trenching in Wonderland revealed several white pieces that over several days gradually disappeared. This sublimation—the direct change of a solid substance to a gas without an intervening liquid phase—showed that the material was not mineral. Noting the findings in mid-June, Smith declared, “We have found the proof that this is water ice and not something else.”

“We are confident now that this is ice,” added Mark Lemmon, lead scientist for stereo-imagery, Texas A&M University. “What excites me is that we can really reach out and touch the ice on Mars now.”

The Phoenix team at the University of Arizona is currently working out the procedures to scrape into this ice layer and move it to the onboard laboratories. This will require that the “pay dirt,” as Smith calls it, be acquired and moved quickly because of the ice’s rapid rate of sublimation. Although very cold—below freezing by Earth standards—the very low atmospheric pressure on Mars gives water a boiling point of only 4 degrees Celsius, or 36 degrees Fahrenheit.

First results announced in late July from the TEGA experiments confirmed the presence of water. According to lead scientist William Boynton of the University of Arizona, the heating of a soil sample showed temperature changes characteristic of heat being absorbed by ice. Donning a witch’s costume hat at the news conference, Boynton gave his best impression of the wicked witch from The Wizard of Oz, “I’m melting, melting.”

Soil

Earlier, Snow White soil samples had been analyzed in the MECA ovens. Ice and volcanic soil alone will not support life; there must be carbon-based or organic molecules to maintain anything similar to the biological systems known on Earth. It is “energy and building blocks that we are looking for,” says Smith.

By “cooking” the sample and examining the molecules that are evaporated, investigators hope to see those organics. In a similar Viking experiment called the GCMS Molecular Analysis (Gas Chromatograph–Mass Spectrometer), no organic material was detected. While there remains some debate over these findings, the mainstream consensus is that the ultraviolet-exposed and oxidative chemical environment on the surface makes it inhospitable to life.

The technique of examining below the surface gives access to a hopefully friendlier microhabitat. As JPL’s lead scientist for the MECA instrument, Michael Hecht stated at a news conference in July, “What native Martian microbes might be able to live and survive and grow in that same soil?”

Samuel Kounaves, wet chemistry lab lead from Tufts University, described the first MECA results during the same conference. “This is the first wet chemical analysis on the Martian soil and any other planet besides Earth by our robotic lab assistant. We basically have found what appears to be the requirements, the nutrients to support life, whether past, present or future.” By “nutrients,” Kounaves did not mean organic materials but salts and other inorganic chemicals.

Kounaves explained that the mix of salts and pH levels were not extreme. “There’s nothing about it that would preclude life.” The preliminary results, he said, show that “The sort of soil you have there is the type of soil you’d probably have in your backyard, alkaline. You might be able to grow asparagus in it really well. This is very similar to the sort of analytical results we got from Antarctica dry valleys.”

In conclusion, Kounaves noted the soil environment seems very livable. “In fact, it seems very friendly. If you had it here on Earth, you could grow something in it very straightforward. There’s nothing about it that’s toxic to an average, ordinary plant here on Earth.”

Life

The bottom-line of our human interest in Mars is the question of life. For one man, that question has already been answered. “The status of the issue of life on Mars may be briefly summarized,” according to Gilbert Levin. Now Director of Science and Technology at Spherix Inc., a health sciences corporation, Levin designed the Label-Release experiment (LR) on the Viking landers.

“Despite all the knowledge now in hand,” Levin writes, “the spectrum of ‘informed’ opinions covers a very broad spectrum with strongly bipolar ends, one populated by those stating that the conditions on Mars make life impossible, and those at the other end accepting life on Mars as proven fact.”

Levin does not merely reside at the “proven fact” end of the continuum; he is the anchor of it. By 1997, he says in a spacedaily.com interview, “it became obvious to me that, all facts considered, the LR had, indeed, discovered living microorganisms on the surface of Mars.”

In his experiment, radioactively-labeled nutrients were added to a surface soil sample collected by the Viking robotic arm, a precursor to the Phoenix system. The results were positive: the materials were broken down and the labeled elements released. These, Levin insists, were the product of living metabolism. Certainly, as Levin readily admits, others do not agree. They argue that a nonliving chemical process created the positive result.

But when combined with the negative (GCMS) organic molecule test, the nonlife end seems to have the more solid ground. Norman Horowitz, another Viking experimenter, was adamant about putting the kibosh to the idea of any life on Mars in his 1986 book To Utopia and Back.

“Since Mars offered by far the most promising habitat for extraterrestrial life in the solar system,” Horowitz wrote, “it is now virtually certain that the Earth is the only life-bearing planet in our region of the galaxy. We have awakened from a dream.”

For many, including Levin, those conclusions are premature and dated. The seemingly simplest arbiter would be, as most learn in grade-school science, to repeat the experiment. But no further label-release experiments have been conducted on the Martian surface. “The failure to pursue NASA’s highest priority (the search for life in the solar system),” Levin says, “cannot be logically explained.”

Levin has suggested new versions of the experiment that would clearly demarcate positive results as either biological or simply chemical in nature, but to no avail, he says. Why NASA’s apparently deaf ear? Levin responds, “It results from NASA's fear of finding out that its original conclusion about Viking was wrong, supplemented by philosophical and religious elements who insist, for non-scientific reasons, there can be no life elsewhere but Earth.”

Digging by Hand

“Stay with us. . . . We have promised to have answers by the end of August,” Phoenix’s Peter Smith assures. These answers will certainly be key to discovering certain aspects of Martian habitability. And, as The Mars Society president Robert Zubrin says, these new revelations will open great panoramas of new insight into the potential of life beyond Earth.

What have the Phoenix results revealed so far? “They certainly make it clear that Mars was once habitable [i.e., had liquid water],” Zubrin told Vision.

But to Zubrin, and to those who will be gathering in August at the University of Colorado, Boulder, for the Mars Society’s 11^th international meeting next week, the challenge lies not in how to design another robot, but in how to visit the place in person. “I think the Viking results were inconclusive. They basically said: ‘If you want to know the truth, come here and find out.’”