Bad news from Mars?

Right after news started circulating that the Phoenix lander had more data from Mars relating to the planet's "potential for life", New Scientist Space Blog, as well as other sources, reported on some preliminary information that may not be what scientists had hoped for. According to the blog, a chemical with extraordinary oxidizing capability, perchlorate, has been found in Phoenix soil samples. Such a substance is very harmful for life and could even "consume any fossil remains of life", according to planetary scientist Mark Bullock. Evidence of strong oxidants in the soil on Mars had also been found by Viking landers. Because perchlorate is also associated with rocket fuel, though, there is the possibility that the soil samples were contaminated. NASA is being very cautious in drawing conclusions, as there have been soil samples taken that show no evidence of perchlorate or other chemicals that seem to be so detrimental to life.