The chemistry and mineralogy of soil samples gathered by NASA’s Phoenix Mars Lander over the past few weeks revealed a troubling fact for scientists who have been digging for clues on Mars habitability. The presence of perchlorate, a highly oxidizing substance, in the Martian soil suggested an unfriendly environment for life forms, but a further analysis remains necessary.

With the help of the Wet Chemistry Lab of Phoenix’s Microscopy, Electrochemistry, and Conductivity Analyzer (MECA), the team of scientists in charge of the mission found traces of perchlorate in two soil samples, but the results from the Thermal and Evolved-Gas Analyzer (TEGA), which heated the samples and analyzed the resulted vapors, found no evidence of the mentioned compound.

“This is surprising since an earlier TEGA measurement of surface materials was consistent with but not conclusive of the presence of perchlorate,” said Peter Smith, Phoenix’s principal investigator at the University of Arizona, Tucson.

The results provided by the instruments aboard the Mars Lander were contradictory: an initial MECA analysis suggested an Earth-like soil, but further analysis evidenced un-Earthlike elements in the Martian soil. So the question that comes to everyone’s mind now is whether the spacecraft may have contaminated the soil samples or the instrumentation. Scientists are working hard on figuring out if the un-Earthlike elements are in fact of Martian origin.

“When surprising results are found, we want to review and assure our extensive pre-launch contamination control process covered this potential,” explained Barry Goldstein, Phoenix project manager at NASA’s Jet propulsion Laboratory in Pasadena, Calif.

On Earth, perchlorate is known as a harmful substance for human health, and has been positively identified in the environment, including in drinking water. The substance is known to interfere with the thyroid gland, which is responsible for regulating the metabolism by releasing hormones.

The presence of perchlorate on Mars raised a lot of questions on the processes going on in the Martian soil. Why wasn’t perchlorate identified in all soil samples? Is perchlorite present only closer to the surface, rather than in depth?

It’s strange how one day, we can almost sense the taste of victory, as we expect NASA to confirm that life on Mars is possible, and the next day, news about an unexpected substance in the Martian soil takes us back to step 1, making us doubt whether life on Mars ever stood any chance.

However, the presence of perchlorate is not the end of the road, and until scientist manage to explain its origin and the ambiguity of the soil sample results, there is one discovery that we should focus on, since it’s been a longtime dream: Martian water.

Last week, NASA confirmed the presence of water in the Martian soil, in a sample taken from a trench approximately 2 inches deep. Since then, the team of scientists has been working on establishing whether the water thaws enough to be available for biology, and whether other essential life components are also present.

The latest discoveries and the good condition of the Mars Lander have determined NASA to extend the Mars mission for an extra 30 days, until September 30. The original mission was supposed to last for three months, but the presence of the spacecraft seems invaluable at this point, when the Red Planet finally began unveiling its mysteries.

NASA promised more details on the recent scientific activities on Mars in a media teleconference scheduled to take place on August 5, at 11 a.m. PDT (2 p.m. EDT). Participants will be introduced at the start of the briefing.