The soil on Mars may contain microbial life, according to a new interpretation of data first collected more than 30 years ago.
Scientists want to know whether or not Mars ever supported life.
The search for life on Mars appeared to hit a dead end in 1976 when Viking landers touched down on the red planet and failed to detect biological activity.
But Joop Houtkooper of the University of Giessen, Germany, said on Friday the spacecraft may in fact have found signs of a weird life form based on hydrogen peroxide on the subfreezing, arid Martian surface.
His analysis of one of the experiments carried out by the Viking spacecraft suggests that 0.1 percent of the Martian soil could be of biological origin.
That is roughly comparable to biomass levels found in some Antarctic permafrost, home to a range of hardy bacteria and lichen.
"It is interesting because one part per thousand is not a small amount," Houtkooper said in a telephone interview.
"We will have to find confirmatory evidence and see what kind of microbes these are and whether they are related to terrestrial microbes. It is a possibility that life has been transported from Earth to Mars or vice versa a long time ago."
Speculation about such interplanetary seeding was fueled a decade ago when researchers said an ancient meteorite found in Antarctica contained evidence of fossil life on Mars. Doubt has since been cast on that finding.
Houtkooper is presenting his research to the European Planetary Science Congress in Potsdam, Germany.
While most scientists think our next-door neighbor in the solar system is lifeless, the discovery of microbes on Earth that can exist in environments previously thought too hostile has fueled debate over extraterrestrial life.
Houtkooper believes Mars could be home to just such "extremophiles" -- in this case, microbes whose cells are filled with a mixture of hydrogen peroxide and water, providing them with natural anti-freeze.
They would be quite capable of surviving a harsh Martian climate where temperatures rarely rise above freezing and can fall to minus 150 degrees Celsius.
Houtkooper believes their presence would account for unexplained rises in oxygen and carbon dioxide when NASA's Viking landers incubated Martian soil. He bases his calculation of the biomass of Martian soil on the assumption that these gases were produced during the breakdown of organic material.
Scientists hope to gather further evidence on whether or not Mars ever supported life when NASA's next-generation robotic spacecraft, the Phoenix Mars Lander, reaches the planet in May 2008 and probes the soil near its northern pole
More about Martain soil.
Since the dawn of time, humankind has had a certain fascination with the stars, planets, and other wondrous phenomena that exist outside of the Earth's atmosphere, but perhaps one of the most intriguing is Mars. Only one planetary jump away, this reddish planet raises more questions than answers. Both the United States and Russia have launched a series of missions to the planet, hoping to survey the landscape as well as search for life. As of today, the most successful program is still the Viking program, launched by the United States in 1975. Vikings 1 and 2 did not find extraterrestrials but did map almost the entire planetary surface. The results of the Viking experiments performed on the Martian soil, however, perplex scientists even today.
The Gas Chromatograph Mass Spectrometer (GCMS) onboard the Vikings concludes that down to 10 centimeters deep the soil does not contain organic molecules. This is inconsistent with conventional wisdom because organics are inevitably produced by meteorite fall. This leads researchers to believe that the soil contains a mechanism that destroys organics. The soil itself is also known to produce oxygen in large quantities when hydrated. The rapid production of oxygen followed by a decrease in production near equilibrium levels indicates chemical as opposed to biological activity.
There are two major problems with testing the Martian soil. Firstly, samples cannot be transported back for testing because the reactions could be dependent on the Martian environment, so the landers must carry out the experiments in situ. Secondly, many techniques perfected on Earth require the use of water, but Mars is relatively dry, so the mixing of water with the soil for experimental purposes may affect the results to a large degree. The exact chemical species present in the Martian soil is unknown, but a well-supported theory suggests that a peroxide exists in the soil or atmosphere, which would explain the lack of organics and the evolution of oxygen when hydrated. This is a concern for future missions because peroxides could lead to the damage of biological and mechanical materials.
NASA researchers believe that palagonite, volcanic soil found in Hawaii, to be very similar to the Martian soil based on its spectra. As a result, palagonite has been selected as the soil of choice for a Martian analog. In this paper, cyclic voltammetry is discussed. Such techniques have never been used in interplanetary missions. Instead methods such as optics, which take up considerable amounts of energy, were used. Voltammetry should be a strong candidate for future missions because it has the ability to speciate, requires relatively little equipment, and uses less energy than more sophisticated devices. The question that arises, however, is whether such techniques would yield viable data. This paper is a pioneer work, attempting to answer that question.
- Peroxide can be detected in the ppm level with and without soil present.
- As more peroxide is added to an electrolyte solution with or without palagonite, the anodic peak current should become more pronounced because there would be a higher concentration of redox species.
- The anodic current should become less pronounced over time because peroxide decomposes over time.
- The pH of the electrolyte should affect the rate of peroxide decomposition. The anodic peak should decrease as the peroxide decomposes.
Methods/Materials & Results
This material has been withheld, because his findings have not been published yet.
These studies indicate that cyclic voltammetry could be used to study Martian soil, but an electrolyte must be carefully chosen with regard to both (1) the chemical thought to be present in the Martian soil and (2) the pH of the Martian environment. Hypothesis 1 is correct because voltammetry can detect peroxide at the ppm level with or without soil present. Hypothesis 2 correctly states that the anodic peak current becomes more pronounced with a higher concentration of peroxide. Hypothesis 3 is validated because the anodic current becomes less pronounced as time passes. Hypothesis 4, however, is incorrect: When an electrolyte's pH is changed with an acid or base, the resulting data does not yield useful information, but an electrolyte at its natural pH does yield useful information. This project concludes that cyclic voltammetry would be ideal for Martian soil experimentation. It has the ability to speciate, requires little equipment, and uses less energy than more sophisticated devices, including optical (e.g. Mars Oxidant Experiments) or gaseous-based machines (e.g. Viking Experiments), while still providing important data. Furthermore, the amount of time it takes to perform voltammetric tests is very short, making it very efficient.