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Where should NASA land its next Mars rover?
THIS WEEK
WITH NASA’s rover Curiosity due to blast off for Mars in November, the debate over the most interesting place to send it is coming to a head. The stakes are high: the $2.5 billion mission offers the best chance yet of finding hints of past life on the planet. Curiosity, aka the Mars Science Laboratory, weighs 900 kilograms. The biggest and most capable rover yet by far, it is the first to carry instruments designed specifically to detect complex carbon-based molecules that could signal life. It will also lay the groundwork for a future mission that will drill below the surface, where organic material would be better preserved. “Awesome science is going to come out of this,” says John Mustard of
Gale Crater A 5-kilometre-high mountain of sedimentary rock that probably formed in the presence of water rises in the middle of the crater. The rocks, which include clays, form distinct layers laid down progressively over time. This offers a gold mine of information about past climate conditions on Mars, probably over a longer time span than any of the other sites. It’s too dangerous to land on the mountain itself, so the rover would drive there from the crater’s periphery. But the landing site has interesting science of its own to offer, boasting a fan of sediment from a river that once flowed into the crater. Mawrth Vallis This is the most mysterious of the sites and appears to be the oldest. Some of its rocks probably date to just 500 million years after Mars
12 | NewScientist | 21 May 2011
Brown University in Providence, Rhode Island. Curiosity will land in August 2012, and over the past few years scientists have put together a shortlist of the best sites for it to explore. This week, researchers debated the merits of the four finalists (see below) at a meeting in Monrovia, California. “They all have deposits that appear to have been put in place by running water,” says Ross Irwin of the Planetary Science Institute, which is based in Tucson, Arizona. One key factor in deciding between them is the distance Curiosity would have to drive to get to the site’s most interesting rocks. “If you have to wait six months to do the science you want, that’s going to be a nailbiting six months,” Mustard says, explaining that the rover or its
–Mawrth Vallis, lovely in August–
instruments could potentially break down along the way. Another point of contention is whether it is necessary to understand the site’s basic history. For example, it is agreed that a river once flowed into a lake in Eberswalde crater, leaving behind a fan of sediment. That is the sort of feature that traps organic material on Earth, so if it were chosen, scientists would know what to look for and where. Mawrth Vallis (circled above) is more mysterious. It has clay minerals that must have formed
Proposed landing sites
Previous landings
PHOENIX
VIKING 1
MAWRTH VALLIS (pictured above)
PATHFINDER OPPORTUNITY EBERSWALDE CRATER HOLDEN CRATER
formed. Clay minerals are especially abundant here, but it is unclear whether the water that formed them came from lakes, rivers or underground reservoirs. That means researchers have a hazier idea of what they might find here. The rover could land directly on the clay-
VIKING 2
GALE CRATER SPIRIT
rich area, though, rather than having to drive there. Eberswalde Crater A river once flowed into this crater lake, dumping a huge fan of sediment on its floor. The river may have run for thousands of years,
in liquid water, but the water’s source is unclear. Still, it has the oldest rocks of all the sites, offering a unique window into the first few hundred million years of Martian history. “That’s when life got started on Earth,” says Mustard, suggesting the same might be true of Mars. NASA will decide on a landing site in June or July. n win a piece of mars See page 38 for a chance to win your very own Martian meteorite
giving any life plenty of time to get a foothold here. The sediment may have trapped organic material that could be a sign of any such life, but the terrain containing the sediment fan is too rugged to land on. Curiosity would drive there from a flatter part of the crater, which was once a lake bed. Holden Crater Right next to Eberswalde, it hosts several fans of sediment that were deposited by water that gushed into the crater in several places. The fans are good places to look for trapped organic material. There are also outcrops that might be the remains of hot springs, which would be good places to look for signs of past life. The area containing the fans in Holden crater is flat enough to land on. However, it is not clear whether Holden hosted a long-lived lake like the one in Eberswalde.
usgs
David Shiga
jpl/nasa
Where to land the next Mars rover?
WITH NASA’s rover Curiosity due to blast off for Mars in November, the debate over the most interesting place to send it is coming to a head. The stakes are high: the $2.5 billion mission offers the best chance yet of finding hints of past life on the planet. Curiosity, aka the Mars Science Laboratory, weighs 900 kilograms. The biggest and most capable rover yet by far, it is the first to carry instruments designed specifically to detect complex carbon-based molecules that could signal life. It will also lay the groundwork for a future mission that will drill below the surface, where organic material would be better preserved. “Awesome science is going to come out of this,” says John Mustard of
Gale Crater A 5-kilometre-high mountain of sedimentary rock that probably formed in the presence of water rises in the middle of the crater. The rocks, which include clays, form distinct layers laid down progressively over time. This offers a gold mine of information about past climate conditions on Mars, probably over a longer time span than any of the other sites. It’s too dangerous to land on the mountain itself, so the rover would drive there from the crater’s periphery. But the landing site has interesting science of its own to offer, boasting a fan of sediment from a river that once flowed into the crater. Mawrth Vallis This is the most mysterious of the sites and appears to be the oldest. Some of its rocks probably date to just 500 million years after Mars
12 | NewScientist | 21 May 2011
Brown University in Providence, Rhode Island. Curiosity will land in August 2012, and over the past few years scientists have put together a shortlist of the best sites for it to explore. This week, researchers debated the merits of the four finalists (see below) at a meeting in Monrovia, California. “They all have deposits that appear to have been put in place by running water,” says Ross Irwin of the Planetary Science Institute, which is based in Tucson, Arizona. One key factor in deciding between them is the distance Curiosity would have to drive to get to the site’s most interesting rocks. “If you have to wait six months to do the science you want, that’s going to be a nailbiting six months,” Mustard says, explaining that the rover or its
–Mawrth Vallis, lovely in August–
instruments could potentially break down along the way. Another point of contention is whether it is necessary to understand the site’s basic history. For example, it is agreed that a river once flowed into a lake in Eberswalde crater, leaving behind a fan of sediment. That is the sort of feature that traps organic material on Earth, so if it were chosen, scientists would know what to look for and where. Mawrth Vallis (circled above) is more mysterious. It has clay minerals that must have formed
Proposed landing sites
Previous landings
PHOENIX
VIKING 1
MAWRTH VALLIS (pictured above)
PATHFINDER OPPORTUNITY EBERSWALDE CRATER HOLDEN CRATER
formed. Clay minerals are especially abundant here, but it is unclear whether the water that formed them came from lakes, rivers or underground reservoirs. That means researchers have a hazier idea of what they might find here. The rover could land directly on the clay-
VIKING 2
GALE CRATER SPIRIT
rich area, though, rather than having to drive there. Eberswalde Crater A river once flowed into this crater lake, dumping a huge fan of sediment on its floor. The river may have run for thousands of years,
in liquid water, but the water’s source is unclear. Still, it has the oldest rocks of all the sites, offering a unique window into the first few hundred million years of Martian history. “That’s when life got started on Earth,” says Mustard, suggesting the same might be true of Mars. NASA will decide on a landing site in June or July. n win a piece of mars See page 38 for a chance to win your very own Martian meteorite
giving any life plenty of time to get a foothold here. The sediment may have trapped organic material that could be a sign of any such life, but the terrain containing the sediment fan is too rugged to land on. Curiosity would drive there from a flatter part of the crater, which was once a lake bed. Holden Crater Right next to Eberswalde, it hosts several fans of sediment that were deposited by water that gushed into the crater in several places. The fans are good places to look for trapped organic material. There are also outcrops that might be the remains of hot springs, which would be good places to look for signs of past life. The area containing the fans in Holden crater is flat enough to land on. However, it is not clear whether Holden hosted a long-lived lake like the one in Eberswalde.
usgs
David Shiga
jpl/nasa
Where to land the next Mars rover?