NASA got a great deal of mileage out of the Mars rovers Spirit and Opportunity, which have lasted far longer than the 90 days originally expected of them when they landed in January 2004. Just this week, in fact, NASA said that Opportunity has surpassed the longevity record of 6 years, 116 days for operation on Mars, surpassing the Viking 1 lander. Spirit, meanwhile, may be done for. Bogged down in loose Martian soil, it may not have been able to position itself to get a good recharge from its solar panels.
Back on Earth, NASA is working on the next generation of Mars rover, named Curiosity, a bigger model that the space agency this week said it hopes to launch between November 25 and December 18, 2011, with a landing on Mars to occur between August 6 and August 20, 2012.
As this artist's depiction suggests, the new rover will be packing heat.
"Curiosity will have a laser on its mast that can take aim at a rock and vaporize a small spot on it," Joy Crisp of NASA's Jet Propulsion Laboratory said in a NASA Science post in October. "This produces a plasma cloud that tells us about that rock's chemistry. We'll look at the light reflected off the cloud to characterize rocks and soils from up to 9 meters away. We'll be able to classify minerals, ices, and organic molecules without having to drive as much."
Curiosity, at left in the artist's rendering here, is much larger than the Spirit/Opportunity generation. That extra size will let the new rover carry more instruments and what NASA promises will a bigger, stronger robotic arm. "The most important difference is that Spirit and Opportunity aren't analytical labs--they are more for observing. This newest rover will be performing a more comprehensive study of the Martian environment," NASA's Michael Meyer said in the October post.
Well, there is at least one other, rather notable difference: Curiosity will be nuclear-powered. The rover will draw its electricity from the heat generated by the radioactive decay of plutonium. NASA says that the radioisotope system will give Curiosity more ample and more consistent power than was the case for the solar-powered Spirit and Opportunity. The expected operational life span for Curiosity will be at least a full Martian year, or 687 Earth days.
This isn't the first time NASA will have packed plutonium in a spacecraft. That was the power source for the Viking landers, which visited Mars three decades ago, as well as for missions including Pioneer, Voyager, Galileo, Cassini, Ulysses, and New Horizons--in short, every spacecraft ever launched beyond Mars.
Known formally as the Mars Science Laboratory, Curiosity is the third in three generations of Mars rovers. In the middle here of this family portrait of scale models, in between Spirit/Opportunity at left and Curiosity at right, is the first generation, the Sojourner rover that landed in the Mars Pathfinder mission of 1997. The image, from May 2008, has the models posing in front of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The full-size, mission-ready Curiosity will stand about 7 feet tall, 9 feet wide, and 10 feet front to back, not counting its robotic arm. It'll weigh close to 2,000 pounds, making it much heftier than Spirit and Curiosity (about 384 pounds) and even more so than Sojourner (24 pounds).
Curiosity will be on the prowl for, among other things, organic molecules--which would indicate whether Mars was ever capable of supporting life. "The rock record is of particular interest," Crisp said in a statement. "It has a record from billions of years ago and can answer questions like 'Where and for how long might Mars have been habitable?' 'Was it cold or warm there in the past?' 'Was the water there acidic or salty?'"
While the actual Curiosity is still in its test and assembly phase, JPL's stand-in has been making the rounds. This full-scale model is making an appearance at the July 2009 edition of the Fortune Brainstorm conference.
Curiosity was originally scheduled to take off for Mars in October 2009. "Despite exhaustive work in multiple shifts by a dedicated team, the progress in recent weeks has not come fast enough on solving technical challenges and pulling hardware together," JPL Director Charles Elachi said in a December 2008 statement. NASA says that the new 2011 date is the next launch opportunity, given that the positioning of Mars relative to Earth means that there's a favorable alignment for only a few weeks every other year.
Here we see the real thing, just above the trio of JPL workers; it's mounted in the backshell that will hold it in the rocket en route to Mars. The backshell is about to be joined to the heat shield at right; together, the two pieces create the Mars Science Laboratory's aeroshell.
In this closer view of the rover, we get a better look at one of its tires, along with the descent stage that will carry Curiosity from the interplanetary rocket to the surface of Mars. (A pair of the descent stage rockets are at top left, with the red caps.)
Laid bare in a JPL facility, the descent stage wraps protectively over the rover. For its several minutes of work, following the heat shield-protected entry to the Martian atmosphere and the deployment of a parachute, the descent stage of the Mars Science Laboratory will use rockets to decelerate as it approaches the surface of Mars.
At a certain point above the surface, the descent stage will hold its position and the rover will ride a tether the rest of the way down.
"Curiosity will even land in a new fashion," JPL's Joy Crisp said in October. "Spirit and Opportunity were sitting on top of a lander that hit on the surface and bounced, protected by airbags, before coming to rest and opening up. They then had to drive off the top of the lander. A descent stage called Sky Crane will gently lower Curiosity (no airbags needed) via cables, which will be cut once the rover's wheels set down."
This spring, NASA has been conducting tests of the landing radar that the MSL descent stage will use. The test flights follow various simulated descent paths factoring in the expected angles and altitudes for the potential landing sites.
Another thing to be checked out in the spring 2010 tests is whether the radar might be confused by the suspended rover itself. Here, the helicopter dangles a mockup of the rover at the Hawthorne (Calif.) Municipal Airport.
The terrain on Mars will make for some rough going for Curiosity. In the "Mars Yard" at the Jet Propulsion Laboratory, an engineering model dubbed "Scarecrow" (because it's not attached to the rover's brains) shows off its flexible suspension during mobility tests.
NASA says that Curiosity should be able to travel as 90 meters in an hour, or just less than the length of a football field, but will probably average just a third of that depending on steepness, soil, power levels, and other variables.
Curiosity's robotic arm undergoes testing at JPL. Scientific instruments on the arm will include the Alpha Particle X-Ray Spectrometer, which will measure chemical elements in Mars' rocks and soil, and the Mars Hand Lens Imager, which will act as a combination magnifying glass and digital camera.
In the body of the rover itself will be other instruments, such as a "sniffer" called SAM, for Sample Analysis at Mars, that will used to detect the presence of gases--methane, for instance, could be a sign of liquid water or microbial activity, NASA says.
The "science-imaging workhorse" aboard Curiosity will be the MastCam, which will consist of two component cameras, identical except for the lenses. One will have a fixed focal length of 34mm for wide-angle views, the other, 100mm, for telephoto shots. The camera supplier, Malin Space Science Systems, is also working on zoom-lens versions that could take the place of the cameras with the fixed focal lengths. That project is being done in conjunction with...
/ Photo: NASA/JPL/Malin Space Science Systems
Mars rover Curiosity
Comparing Curiosity with Spirit
Three generations of rover
Curiosity at Brainstorm
Backshell and heat shield
Rover in backshell
Rover on a string
Wheels within wheels
Landing site candidates
...Hollywood director James Cameron (left), the man behind "Avatar," "Titanic," "Aliens," and "The Terminator." He's seated here with NASA Director Charles Bolden. The cameras (whether zoom or fixed-length) will be capable of taking both still images and high-definition video.
NASA is still working to determine the optimal site to deposit Curiosity, and in late 2008 narrowed its list to four finalists: "Eberswalde, where an ancient river deposited a delta in a possible lake; Gale, with a mountain of stacked layers including clays and sulfates; Holden, a crater containing alluvial fans, flood deposits, possible lake beds and clay-rich deposits; and Mawrth, which shows exposed layers containing at least two types of clay."