Image: Mars Science Laboratory
NASA  /  JPL
This all-terrain, all-purpose machine will explore Mars like never before.
By Senior Space Writer
updated 2/11/2004 9:45:38 PM ET 2004-02-12T02:45:38

While the Spirit and Opportunity rovers wheel themselves into the history books of Mars exploration, get ready for the next giant leap in rolling across the Red Planet.

The Mars Science Laboratory is an all-terrain, all-purpose machine, akin to an extraterrestrial Sport Utility Vehicle.

To be rocketed toward Mars in 2009, this long-range, long-duration robot is a trend setter. It will scope out Mars like never before to assess that puzzling planet as a potential habitat for life — past or present — and help verify if human explorers could exist there in the future.

Imaginative engineering
Work on the Mars Science Laboratory is under way here at the Jet Propulsion Laboratory. And it is obvious from the get-go that just getting this mega-rover onto Mars takes a strong dose of imaginative engineering.

The Mars Science Laboratory would make the first wheels-down landing on the planet. No need for airbags, nor lengthy preparations to get the mobile robot "down-and dirty" on Mars.

This Mars vehicle is lowered onto the surface via a Skycrane and ready for action, said Brian Muirhead, JPL's chief engineer for the MSL.

Muirhead admits that the Skycrane idea evokes "this is crazy … you've got to be kidding" comments from some people.

"I heard exactly those same words on the airbags," said Muirhead, who was a key leader in the Mars Pathfinder/Sojourner project — NASA's first Mars craft to use airbags. Spirit and Opportunity rovers now scuffing up Martian landscape also utilized airbags to reach their respective landing zones.

"But once you think about it a little bit … the Skycrane is absolutely better than airbags," Muirhead advised.

Hang time
After diving through the Martian atmosphere and then under blossomed parachute, the Skycrane/MSL hardware would be set free to maneuver over Mars.

The Skycrane frame carries propellant tanks topped-off with hydrazine propellant, as well as two "outriggers" — each outrigger equipped with a set of 700-pound thrust rocket motors. These controllable engines first run hot and heavy to slow the structure down. By reducing motor thrusting, the Skycrane eases on down toward Mars.

Image: Skycrane concept
NASA  /  JPL
By using the skycrane concept, the Mars Science Laboratory can immediately begin exploring on impact.
Using guidance and navigation gear, the Mars-bound hardware enters hover mode for a nominal five seconds. In a steady-as-she-goes manner, it hangs in midair a mere 15 feet (5 meters) above a predetermined slice of Martian real-estate.

From there the Mars Science Laboratory slips down a tether to reach Mars. Its depositing duty complete, the Skycrane departs the scene for a crash landing distant from the rover's arrival area.

No fuss. No muss. No miles of bouncing. MSL's touchdown speed would be modest: one yard (meter) per second. "That's like falling from 3 inches on Earth," Muirhead told Space.com. "We're six wheels on Mars instantly.

"The concept is very solid. One of the things that we really like about this … it's very testable on Earth," Muirhead said. A facility to help flesh out the Skycrane idea is being built at China Lake — a large Navy test complex about 150 miles (240 kilometers) northeast of Los Angeles.

Energizer bunny
The Mars Science Laboratory's landing ellipse — the zone within which a spacecraft attempts to land — is 6 miles by 3 miles (10 kilometers by 5 kilometers). That accuracy is nearly a factor of 10 better than the aiming for Spirit and Opportunity.

Where exactly on the Red Planet the Mars Science Laboratory is destined to put down is still to be determined. "We want to be able to go plus or minus 60 degrees in latitude at any season," Muirhead said.

The mobile lab is five times larger than the current wheeled robot design now busily at work on Mars. That class of rover is around 400 pounds (180 kilograms). The heftier MSL could tip the scale at 1,980 pounds (900 kilograms).

What drives that weight up is the science gear that will be toted across the Martian terrain — 10 times the payload of a Spirit/Opportunity-class rover.

The Mars Science Laboratory is designed to operate a full Martian year, or two Earth years.

At present, Boeing Co. and Lockheed Martin are working on competing nuclear battery designs for the laboratory. Boeing's Canoga Park, Calif.-based Rocketdyne Propulsion and Power unit is designing a so-called Multi-Mission Radioisotope Thermoelectric Generator, or RTG, a more powerful version of the RTGs that powered NASA's Viking 1 and 2 Mars landers in the 1970s.

While the Multi-Mission RTG would not be as powerful as the RTGs aboard NASA's Cassini Saturn probe, it is designed to be more flexible, adaptable to both the orbiter and lander missions on the space agency's drawing boards.

Given a nuclear power plant that it carries, the rover would be the energizer bunny of Mars by going … and going … and going … for a number of years.

On Mars, size matters.

"We believe that a bigger vehicle has a lot more mobility," Muirhead said. With MSL's large wheel diameter, it can steer itself to exotic sites as well as chalk up serious distance much easier. And thanks to a more precise landing ellipse, the rover could touch down in a reasonably safe place and then trek to a much more hazardous region, he said.

The now-forbidden, "do not trespass" canyon region of Valles Marineris is a possibility for MSL roving.

Clean as a whistle
One of the big and costly challenges facing the MSL program is planetary protection.

MSL is being sent to Mars to storyboard just how habitable the planet was in the past, or whether that faraway world now serves as a haven for life.

That means the rover must be free of any hitchhiking Earth bugs, and be organically clean, too. Great care must be taken, therefore, in assuring that any microbial life detected by MSL aren't hangers-on from our own planet.

That being said, going to a chosen region that may be an abode for life means MSL must be sterilized. Without taking a clean-as-a-whistle approach, MSL could "foul the nest," so to speak, at Mars.

"If you were to crash in a mud puddle on Mars — if such a thing existed — you would have created an environment where terrestrial bugs could grow. And that would be terrible …contaminating the planet big time," Muirhead said.

In the event of a crash-landed rover, the robot's nuclear-energized power supply could possibly create a liquid water region - an unwanted Martian meltdown of ice.

A major assessment is under way to agree on a plan for spacecraft sterilization.

Chemistry of whatever
Development cost of the Mars Science Laboratory is slated to be below $850 million. With the price tag of either a Delta 4 or Atlas 5 booster tossed in, along with a rover-ready nuclear power pack, sterilization expenses and mission operations, MSL adds up to a billion-dollar-plus probe.

Later this year, the type of science gear loaded on MSL will be determined. What's wanted is an analytic suite of instruments. Already included is a core drill and crusher that delivers ground-up samples for detailed, onboard study.

"We can get into soil, rock and ice. We can core anywhere," Muirhead said. "We actually have the capability to understand the chemistry of whatever we find on Mars," Muirhead said.

The MSL is a "discovery-driven" mission. It will be dispatched to a scientific sweet spot on the Red Planet, picked because of the findings from earlier orbiters and landers.

"What this mission is about is habitability … understanding the ability of Mars — past, present, or future — to sustain life," Muirhead concluded.

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