Vast Ice Fields Suggest Life on Mars Possible
Just days after starting its science mission, a new spacecraft orbiting Mars has struck pay dirt, detecting vast fields of ice that scientists say provide evidence of sufficient water to make it possible for the planet to have harbored life.
The discovery is a coup for NASA, whose leaders are using a “follow the water” strategy to understand the evolution of Mars and look for signs of past and present life there. The presence of water would also be key to any future attempt to have astronauts explore the Martian surface.
“Water is vital to life. Water has changed the surface of Mars in the past. And water is essential to the future exploration of Mars,” R. Stephen Saunders, the Jet Propulsion Laboratory’s project scientist for the Odyssey orbiter, said at a news conference Friday in Pasadena to release the findings.
Results from planetary missions often take months, if not years, to be collected, analyzed and released to the public. The new results are unusual because they come so early in the mission, “from the first few days, in some cases the first few hours, of exploration,” Saunders said.
The normally cautious scientists were able to make strong conclusions so quickly because “we really have a whopping large signal,” said William Boynton, a planetary scientist from the University of Arizona who directs the instrument that detected the ice. “It really just blew us away when we looked at it.”
Boynton’s team used a gamma ray spectrometer to probe the chemistry of the Martian surface. The instrument can detect the chemical constituents on the surface, including the hydrogen atoms contained in water molecules, by analyzing the unique gamma ray signatures emitted by each element.
The instrument has been called a “virtual shovel” because it can read signals from underground, in the shallow surface layers of Mars.
“The signal we’re getting is loud and clear. There’s lots of ice on Mars,” Boynton said. “We’re not just looking at surface frost. It’s a fair amount of ice.”
Scientists have long known that Mars had some water. But until now, there were not enough data to tell whether water was found only in a few isolated places or was widespread on the planet’s surface. The wider the distribution of water, the more chance there may have been for life to develop on the planet, scientists believe.
The ice was found on the southern hemisphere of the planet, where it is now approaching fall. Scientists know the water is frozen, Boynton said, because of temperature readings showing “it’s just too darn cold for it to be liquid.”
Boynton could not say how much ice is there. The findings are so new that his team had not yet done the complex calculations necessary to make such an estimate.
Odyssey, the first spacecraft to reach Mars since two Mars missions failed in 1999, will enable scientists to conduct the first chemical analysis of the entire Martian surface and map the surface with great detail.
The instrument doing much of this work is a thermal emission camera called Themis that takes regular images of the surface during the day and infrared images at night.
Thermal images show temperature differences on the surface: Rocks that have been heated by the sun look bright while cold rocks in shadow or under dust look dark.
The images are “the equivalent of super night-vision goggles,” said NASA project scientist Michael Meyer. The new images are the first taken of the Red Planet at night.
While night-vision images taken on Earth are often muddy and grainy, the new Themis images are so crisp and clear they surprised Philip Christensen, a planetary scientist from Arizona State University who leads the team operating the camera system.
“We had no idea what to expect,” he said. “Mars turns out to have remarkable variability,” he added. “We see craters. We see mesas. We see rocky places.”
Entire Surface to Be Mapped
Images taken in the first six hours of the mission are already yielding some insight into Martian geology and provide clues to which areas might be most likely to harbor signs of life and which would be best to avoid.
The images show that rocks ejected out of the centers of craters remain warmer than crater bottoms and that some of the sinuous channels crossing Mars are much colder than the surface--filled with cold dust about 150 degrees below zero.
A different camera that has been orbiting Mars for several years aboard a spacecraft called the Mars Global Surveyor takes daylight pictures of small patches of Mars at very high resolution. The new camera takes lower resolution pictures that cover large swaths of the surface and can be used to create a detailed map of geological features across the entire surface of the planet.
Such details, NASA officials said, will help pinpoint the safest and most geologically interesting places to land robotic vehicles on Mars in future missions.
Things are not going as well for the orbiter’s third instrument, the Martian Radiation Environment Experiment known as “Marie.” These sensors, built to measure radiation that could harm future astronauts traveling to Mars, stopped communicating in August.
Now that Odyssey has settled into orbit, engineers will begin trouble-shooting the instrument and attempt to repair it, said Frank Cucinotta, who is leading the experiment from the Johnson Space Center in Houston.
Measurements made before the instrument failed, he said, suggest that astronauts traveling to Mars would experience twice as much radiation as those working in the international space station.
Scientists said the images released Friday are just the beginning of a flood of information that will unveil the basic geology and chemistry of Mars. “Our odyssey,” said Saunders, “has just begun.”
It’s about time for Boynton, who was heartbroken in 1993 when a gamma ray instrument he’d worked on for years was lost along with the spacecraft carrying it toward Mars.
“I kind of feel I’ve been on my own odyssey for 16 years trying to make this happen,” he said.
