NASA Returning to Mars With Tough Twin Rovers

More eager than ever to explore the surface of Mars for traces of water and life, NASA officials announced Thursday that they will double the size of their next mission in 2003 and send identical twin rovers to probe the planet.

“We are returning to Mars, this time in force, with twins,” said Scott Hubbard, director of NASA’s Mars program.

The twins are bigger, faster and more rugged cousins of their diminutive predecessor, Sojourner, which enraptured the world when it ambled across the Red Planet in 1997. “This is the SUV of Mars rovers,” said Steven Squyres, a planetary geologist from Cornell and lead scientist for the experiments on the rover.

Dubbed “robotic field geologists,” the new 4-foot-square rovers will be able to scan the horizon with 20/20 and infrared vision for traces of ancient water, use sophisticated software to travel around obstacles without human help, and extend lanky arms to scrape open Martian rocks and examine them through magnifying lenses.

“We haven’t seen the underbelly of Mars at this scale before,” said Jim Garvin, a geologist and NASA’s chief scientist for Mars missions. “That’s a discovery no matter what it shows.”

Once they land in January 2004, the rovers will be able to move 100 yards, the equivalent of a football field, each day. That’s farther than Sojourner moved in its entire 90-day life span.

The new-generation rovers will borrow one thing from the past: They will use the same “bounce and roll” air bag landing that proved successful in 1997.

Stung by repeated failures of Mars missions last year that were attributed to excessive cost cutting, NASA has taken several steps to increase the likelihood of this mission’s success.

First, not only are the new rovers technologically superior, they are considerably more expensive. The cost for the first rover is $350 million to $400 million, which includes launch costs and healthy cost buffers for unexpected overruns. The second rover is expected to cost $200 million. The rover that was lost last year cost $235 million, including $70 million for the launch.

In addition, the two spacecraft will emit tones continually through entry into the Martian atmosphere, descent and landing, so that the fate of the rovers can be determined if they are lost.

The spacecraft will be launched separately on Delta II rockets from Cape Canaveral on May 22 and June 4, 2003. Sending two rovers will help offset the higher costs of the mission because engineers at the Jet Propulsion Laboratory in Pasadena can make two for the price of about one and a half.

NASA officials made the decision to send two rovers because the lineup of planets in 2003 is opportune for launching heavy spacecraft toward Mars and communicating with them from the planet’s surface. Orbit configurations limit launch windows to every two years, but opportunities to land occur at considerably longer intervals. The next one won’t occur again until 2009, said Ed Weiler, a top NASA administrator.

Launching two spacecraft also will allow scientists to pick two very different landing sites. “Perhaps one that is safe, perhaps one that is more aggressive,” said Weiler.

NASA will spend the next two years analyzing images of the planet now being taken by the orbiting Mars Global Surveyor to detect possible landing sites.

One possibility is a 200-foot-wide crater called Holden, considered geologically interesting because it contains layered rocks that suggest a lake once filled the crater. Another possibility is a site at the equator that contains large amounts of iron oxides, minerals formed in the presence of water, said Philip Christensen, a geology professor at Arizona State University. His team detected the minerals from the orbiting Surveyor.

In a stunning announcement earlier this summer, NASA said that recent photos from the Global Surveyor show what appears to be the seepage of water in the very recent geological past or even today. But engineers will not try to land craft near those sites, which are on steep slopes and could be reached only with precision landing or a rover that could climb a 45-degree slope. “We don’t have that technology right now,” said Weiler.

While the rovers also will not conduct tests to search for life per se, they will be able to analyze a variety of martian rocks up close to search for traces of life or ancient water that may have once supported life.

Unlike previous missions, including last year’s failures, the 2003 missions will not use outside contractors to build the rovers. They will be built in-house, at JPL. Contractors may be used, but only for portions of the spacecraft. And engineers already have a head start.

In a recent successful test, scientists directed a prototype rover remotely from JPL while it ambled across the Nevada desert examining rocks--coming to the same conclusions as a human geologist at its side.

Still, JPL scientists must figure out how to manage two rovers on the planet at the same time, said Firouz Nadiri, who manages the Mars program at JPL. If launched as planned, the rovers are expected to land 18 days apart in January 2004 and explore the planet for about 90 days--or until their solar panels become so covered with dust that they stop functioning.

They primarily will search for areas that contained water in the past and therefore may have contained life. It is known that oceans once covered Mars, but they have evaporated and frozen into ice.

Certain minerals provide telltale traces of previous water because they are formed only in water. These include the carbonates that make up limestone, iron oxide and special minerals that form at hot springs or when lakes evaporate. The rovers will carry an instrument that can detect the unique infrared signatures of different mineral types.

While an infrared scan of the planet is now being done from space, the rovers will be able to examine individual rocks for the first time. “I’m really excited,” said Christensen, the scientist from Arizona in charge of the infrared instrument. “It’s almost like being able to walk across the surface yourself and put rocks in your pocket.”

The rover prototypes look like robotic dogs. They have six wheels underneath stout bodies. A panoramic camera--one of several on the vehicle--sits atop a thick mast. A small antenna sends out data. An arm about the length and dexterity of a human’s can extend from the body to scrape open and examine rocks.

Each of the short, squat rovers will weigh 330 pounds. “That’s almost exactly as much as Shaquille O’Neal,” said Nadiri, an avid Lakers fan who has begun to use his favorite player as a unit of measurement. He compared the 24-pound Sojourner rover to “a baby Shaq.”

NASA plans to broadcast every minute of the mission over the Internet so the movements of the rovers can be tracked by the public. “It’s going to be a shared adventure,” said Squyres, who added that broadcasting a live mission means that scientists cannot hide behind massaged or edited images. “If the rover gets in trouble, you’re going to see that too.”

The plans for the rovers will change from day to day, depending on where they land and what they see around them. NASA engineers plan to send a rover new commands each morning at 10 a.m. and have it work until 3 p.m. “This rover,” said Nadiri, “essentially keeps banker’s hours.”