New Signs of Water Found on Mars
NASA scientists have discovered evidence that liquid water may have recently existed on Mars. Water has long been sought on the surface of the Red Planet because it is thought to be an essential prerequisite for life.
The findings, which were still being kept a closely guarded secret Wednesday, are expected to reveal that deep springs may have allowed water to reach the planet’s surface. The National Aeronautics and Space Administration plans a news conference today in Washington to discuss the new images from the Mars Global Surveyor, a spacecraft now circling the planet.
Although many planetary scientists were excited about how the finding could reinvigorate Mars exploration, others cautioned that the results were preliminary and not proof that the planet was capable of supporting life.
It is thought that there would need to be a long-standing lake or pond for life to evolve. But that is unlikely for a planet with temperatures that dip to 220 degrees below zero Fahrenheit and a thin atmosphere in which liquid water evaporates almost instantly.
“I don’t think there’s any great shift in paradigm,” said David Paige, a planetary scientist at UCLA and a leading Mars researcher. “We need to hear more before we start jumping up and down.”
It is clear, from canals and other features on the planet’s surface, that vast amounts of water flowed across Mars more than 3 billion years ago, when the planet was much warmer and wetter. As the planet cooled, much of that water froze.
The current finding, an amplification of one initially made two years ago, suggests that heat sources from within the planet--volcanoes and radioactive decay of natural elements--may be enough to melt ice deep under the surface so it can bubble to the surface in streams.
“It’s not unexpected,” said Victor Baker, who heads the hydrology department at the University of Arizona and is among a group of scientists who have maintained for several years that liquid water exists on Mars underneath the surface ice.
An image from the Global Surveyor two years ago showed V-shaped trenches on the wall of a crater that could have been carved by flowing water. It also showed what looked like the remains of a pond or lake.
At the time, NASA cautioned that the features could also have been caused by flowing lava.
Baker said word among planetary scientists was that new images of the same area confirm that the changes to the crater appear to have been caused by water and not lava.
“What it indicates is that water is still there on Mars at places quite near the surface that are accessible. These then become high-priority areas for robotic missions or, eventually, if we send people to explore Mars,” he said.
There are many challenges to exploring the area. NASA would need to land a spacecraft in a precise location and have a rover navigate difficult terrain to reach the crater. Baker said it would be wise to use different imaging instruments to search the planet for more possible stream locations because they could be widespread.
Scientists involved in the project refused to comment until their news conference today. The scientists heading the study are Michael Malin and Ken Edgett, staff scientists of Malin Space Science Systems in San Diego.
The findings were originally scheduled to be announced June 28, the day before they were to be published in the journal Science.
The announcement was moved up because preliminary reports of the finding were posted Wednesday on a Web site, https://www.space.com. NASA officials said many published reports about the findings were erroneous and exaggerated the importance of the findings.
“The reports so far have been overblown,” said one NASA official. “I think people are going to be disappointed” when they hear the full results, the official said.
It is not certain, scientists said, whether certain features of the planet are seeping water. They would be of less interest if they were ancient and only indicated, as scientists already know, that water flowed freely on the planet in its warmer past. It is possible that the features are up to a million years old--geologically recent, but too old to harbor current life.
It is also unclear whether the streams, if currently active, would provide a stable area of liquid water like a puddle or a lake, that might have the potential to harbor life.
“It’s another data point on a very long journey,” said John P. Bradley, a planetary scientist and adjunct professor at Georgia Tech’s School of Material Sciences and Engineering who is an expert on the possibility of life on Mars.
Most scientists are interested in the findings because of what they say about the evolution of life forms and how water behaves on a planet other than Earth. While some media reports have discussed the idea of astronauts or future colonists using the water, most scientists scoff at that notion.
“The water could be really salty--there’s no guarantee it’s Evian,” said Paige, who was not involved in the current study.
NASA officials did apparently deem the findings important enough for a White House briefing. Vice President Al Gore told reporters on his campaign plane Wednesday that he had learned of the finding two weeks ago.
NASA Administrator Dan Goldin is seeking funding for next year’s budget while contending with congressional inquiries about mishaps that led to the loss of two Mars spacecraft in 1999. Some scientists wondered if the timing of the announcement was made to improve NASA’s budget prospects.
Even though a finding announced by NASA in 1996 about potential signs of life in a Martian meteorite has since been largely disproved, funding for research on life in space has increased dramatically. Hundreds of scientists are now involved in the pursuit.
Astrobiologists have recently become more excited about the prospect of finding life on Europa, one of Jupiter’s moons. Evidence suggests that a large ocean may exist underneath its frozen shell and that warm plumes may partially melt the ice in places and provide possible niches for life.
For now, though, most eyes are again back on the Red Planet.
“Mars doesn’t disappoint. It keeps coming back,” said Louis Friedmann, executive director of the Pasadena-based Planetary Society and an unabashed fan of Mars exploration. “Mars is special because it’s the nearest thing we know of that’s like Earth. It’s this almost reachable place.”
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Search for Water
Scientists have discovered an area of Mars where liquid water may recently have flowed, which could indicate the potential for life. But planetary experts cautioned that the findings are preliminary.
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The image below, from the Mars Global Surveyor, originally published in 1998, shows an area in the southern highlands of Mars called Noachis Terra. The age of the features is unclear, but they could have been created relatively recently in geologic time.
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Sources: NASA, Jet Propulsion Laboratory
