14 DAY TRIAL // NASA's Spirit Mars rover is cruising through the Gusev crater and now it has arrived to a site called the "Home Plate", the most spectacular layered rock the rovers have found so far. As images arrive, the scientists are baffled. The Home Plate stood out in overhead images taken by Mars Global Surveyor's Mars Orbiter Camera and has been set as target for Spirit since shortly after the robot landed in January 2004.
Steve Squyres, lead Mars Exploration Rover scientist at Cornell University describes the atmosphere at NASA: "Many of us were pretty much reduced to incoherent babble? like 'WOW!!', 'Holy Toledo!' ? in our e-mails to one another as the first good pictures were coming down."
"I think it is one of the most picturesque views that we have encountered in either mission thus far. It is a spectacular scene, with Home Plate and all the ridges and buttes." said Jim Rice, a rover science team member at Arizona State University in Tempe. Rice points out that the nature of the layered site is not yet known - "we're not sure what it is yet".
As the rover got closer and closer to the plate and studied the surrounding area, the speculations about the nature of the plate had diversified. One initial idea was that it might be the remains of what once was a water basin.
"It has a shape when seen from above that is reminiscent of a playa or evaporite basin? so that has made it a point of possible interest in a mission seeking evidence for past water on Mars," said Larry Crumpler, research curator for volcanology and space sciences at the New Mexico Museum of Natural History and Science in Albuquerque.
Other hypotheses suggest the plate is made out of impact deposits, volcanic deposits, maybe wind-deposited or water-lain sediments. Another more audacious hypothesis is that it is a volcanic of a hydrothermal vent structure.
However, Crumpler said that to settle the debate more detailed rover images are needed and it is needed for Spirit to make use of its instruments on its robot arm. "Everything is on the table until we've gotten more data down", Squyres said.
Photo credits: NASA / JPL-Caltech