Spacecraft Draw Closer to Mars

John Roach
for National Geographic News

December 12, 2003

Spacecraft from three different space missions are drawing closer to Mars. Over the next six weeks, landers and rovers are scheduled to touch down on the red planet's surface. Together with orbiting spacecraft, the probes will poke, scratch, sniff, and image the Martian environment for clues to the existence of past or present life.

Mission scientists will clear a significant hurdle to see their spacecraft simply reach Mars.

"Mars has been a most daunting destination," said Ed Weiler, NASA's associate administrator for space science at a press briefing earlier this month in Washington, D.C. "Some, including myself, call it the 'death planet.'"

Historically, two out of every three missions to Mars have failed—a testament to the difficulty of enduring a 300-million-mile (480-million-kilometer) journey from Earth. NASA's Mars Polar Lander and Mars Climate Orbiter were lost upon arrival in 1999.

But space scientists around the world hope the current wave of spacecraft scheduled to reach Mars in the coming weeks, one as early as Sunday, will yield at least a few success stories.

The five spacecraft from three agencies are on unrelated but complementary missions to study the red planet's atmosphere, soil, and rocks for signs that Mars could have—or still does—harbor life.

The first among the current wave of spacecraft to reach Mars is Nozomi, a spacecraft operated by Japan's Institute of Space and Astronautical Science. Nozomi was scheduled to enter Mars' orbit Sunday, but owing to an unresolved electrical problem the agency has adjusted the spacecraft's altitude so that it will shoot past Mars and become an artificial planet in orbit around the sun.

The next chance for success is the European Space Agency's Mars Express mission. The Mars Express probe is expected to release the Beagle 2 lander on December 19 for a Christmas Eve touch down. Mars Express will enter Mars' orbit Christmas Day.

The first of NASA's current Mars Exploration Rovers, Spirit, is scheduled to arrive January 3, 2004. Opportunity will arrive January 24.

As the spacecraft make their way to Mars, mission scientists are striving to ensure a safe arrival and, in the event of problems, avert harm to the Martian environment.

"Everybody knows there's a potential that bad things can happen to good spacecraft. We are trying to avoid that," said John Rummel, a NASA researcher in Washington, D.C., who chairs the Paris-based Committee on Space Research's planetary protection panel.

Doomed Nozomi

Nozomi, which means "hope" in Japanese, was launched in 1998 and originally scheduled to enter Mars' orbit in 1999 on a two-year mission to study the red planet's atmosphere. Problems for the spacecraft began soon after launch.

A glitch in the engine system developed as Nozomi broke free from Earth's gravitational field, causing the spacecraft to consume too much fuel. To make up for the loss, its flight path was altered. Mission engineers sent the craft looping around Earth twice for a gravity assist.

Then, while on track for a 2003 arrival, a solar flare in April 2002 disrupted the spacecraft's electrical systems. Engineers have worked without success since July 2002 to fix the problem.

To avoid a one percent chance of a crash landing on Mars, which would potentially contaminate the planet with microbes the craft has collected since its 1998 launch, mission scientists announced Tuesday their plans to adjust Nozomi's altitude and send it into orbit around the sun.

"They've stated publicly if they can't guarantee a successful Mars orbital entry they will take steps to avoid Mars altogether. That is all you can really ask of anybody," said Rummel.

Mars Express and Exploration Rovers

Mission teams for the European Space Agency's Mars Express orbiter and rover and NASA's twin Mars Exploration Rovers are busy preparing for on-schedule and error-free arrivals at Mars.

Dave Lavery, a leader of solar system exploration, including the Mars missions, for NASA in Washington, D.C., said the spacecraft have nearly completed the easy leg of their mission, from development to interplanetary travel.

"The really hard part starts when we get to Mars and begin the EDL process—entry, descent, and landing," he said. "That will slow the spacecraft from an approach speed of 12,000 miles per hour [19,000 kilometers per hour] down to zero in just six minutes. That will be followed by a very intense three months of operating the rovers on the surface of Mars."

Mars Express, the European Space Agency's first mission to Mars, launched June 2. If the lander drop-off and orbiter insertion go according to plan, mission scientists should receive data from the Martian surface on Christmas Day.

The Beagle 2 lander will study the red planet's rocks and soil for signs of past and present life while the orbiter will examine the Martian atmosphere and use remote sensing instruments to study the planet's structure and geology.

The first of NASA's golf-cart sized Mars Exploration Rovers, Spirit, launched June 10 and its twin, Opportunity, launched July 7. The pair will touch down at locations thought to have once contained water, a key ingredient for life.

"Can we guarantee success? Of course not," said Charles Elachi, director of NASA's Jet Propulsion Laboratory in Pasadena, California, during a press briefing earlier this month in Washington, D.C.

"On the other hand, I would say the team deserves it," he said. "Because they have done everything humanly possible that we know about to be able to minimize the risk and enhance our possibility of succeeding."