Open science promised for Phoenix
The US space agency (Nasa) has quashed any idea that it is hiding information related to discoveries made on Mars.
Nasa has acknowledged that its Phoenix probe has seen an unexpected compound - perchlorate - in the Martian soil but says the analysis is incomplete.
Scientists said they had not discussed the issue publicly earlier because they were unsure of the data's significance.
They said the discovery - if confirmed - was fascinating but made "life on Mars" neither more nor less likely.
Peter Smith, the Phoenix principal investigator from University of Arizona, stressed that his team would be completely open about its investigations.
"Our policy from the beginning has been to show all our pictures as they come in and to try to involve the world, along with us, in exploring Mars for a habitable zone," he told reporters.
"We really feel it's time to let everybody know what we're finding and get that window into our project."
The fuss had kicked off over the weekend when rumours swept the web that major findings from Phoenix were being held back.
The source of this internet storm was an Aviation Week article that claimed the "White House has been alerted by Nasa about plans to make an announcement soon on major new Phoenix lander discoveries concerning the 'potential for life' on Mars".
The respected magazine further claimed that scientists working on one of the Phoenix instrument suites had even been kept out of a press conference last week to avoid the risk they might have to answer questions on the subject.
That subject - Nasa has now confirmed - is the detection in the Martian soil of a strong perchlorate signal.
Water story
Perchlorate (a compound containing chlorine and oxygen) is a potentially oxidising substance often seen in arid soils on Earth, such as in the Atacama desert in Chile.
Although the super-dry Atacama was often regarded as being hostile to life, the same assumption should not be made about the presence of perchlorates, the Phoenix team said.
"[On Earth] there are a large number of plants that concentrate perchlorate and grow in perchlorate at certain levels; there are a variety of species of bacteria that utilise perchlorate as a substrate in their metabolism," explained mission scientist Sam Kounaves, from Tufts University.
The apparent perchlorate signal was seen by the probe's Microscopy, Electrochemistry, and Conductivity Analyzer (MECA), but Nasa stresses that complementary analysis is needed to confirm the data and finesse the details.
On Earth, perchlorates are created in the atmosphere by the interaction of aerosols or dust particles in sunlight, and are dry-deposited onto the surface.
In a desert setting, they stay at the surface; but in wet regions, they will quickly move through the soil.
"Perchlorates will tell us quite a bit about the history of water, not just at the Phoenix landing site but in other parts of Mars as we continue our exploration," explained Richard Quinn, a Phoenix researcher from Nasa's Ames centre.
"Currently, we've seen the perchlorates at the surface and a future line of research will be to look at where else they are on the planet and whether or not water and salt mobility was involved in that transport."
Phoenix scientists have more time to work up their findings. The US space agency recently agreed to add another five weeks to the original 90 days of the prime mission.