Mars is getting crowded. A new NASA orbiter slips into Mars orbit on Sunday, followed closely by India's first interplanetary probe, a comet, and then a rush of countries proposing their own entries to the new space race to Mars.
NASA's Mars Atmosphere and Volatile EvolutioN mission (MAVEN) is scheduled to enter Mars orbit Sunday night after a ten-month journey. The $671 million mission joins NASA's two robotic rovers on the surface and two orbiters circling Mars, plus the European Space Agency's Mars Express orbiter. (Read "Visions of Mars" in National Geographic magazine.)
That's if nothing goes wrong, of course—the red planet also holds the wreckage of NASA's Mars Polar Lander and Europe's Beagle 2, reminders of the history of Mars mission mishaps: Roughly half of all spacecraft sent to the planet have crashed or gone off course.
Undeterred, a host of nations are planning or contemplating more trips to Mars. And then there's space entrepreneur Elon Musk of SpaceX, who dreams of putting human colonists on the planet.
Mars, say space policy experts, looks like the planetary destination of choice for the rest of the decade. (Related: "Top 5 Challenges in Store for Mars MAVEN Mission.")
"Bottom line—all the major spacefaring countries have had, will have, or hope to have robotic Mars probes," says space policy analyst Marcia Smith of SpacePolicyOnline.
Why Mars? "Fundamentally, all the investigations seem to revolve around the question of life on Mars," says space historian Roger Launius of the Smithsonian's Air and Space Museum in Washington, D.C. Though the search has shifted over the decades from finding Martians to simply looking for evidence the planet was habitable in the distant past, "we have not completely abandoned those beliefs" in Mars as an abode of life, he says. (Related: "Making Mars the New Earth.")
And MAVEN is "our next big step on our journey to Mars," says NASA's Lisa May, speaking at a Wednesday briefing on the mission. MAVEN is "on schedule and ready to go," she added, with a rocket burn set to nudge the spacecraft into orbit around Mars.
MAVEN aims to tell the story of how Mars went from a warm and wet planet more than four billion years ago to the cold, dry desert of today. These days Mars has a tenuous atmosphere, only 0.6 percent as thick as Earth's. By measuring the rate at which light gases such as hydrogen escape into space, MAVEN will let scientists backtrack the history of the planet's atmosphere.
Next, India's Mars Orbiter Mission (MOM) spacecraft arrives on September 24. The Indian Space Research Organisation pronounced the $73 million spacecraft in the "pink of health" on Twitter last week, ready for a steering rocket firing that will place the mission on track to arrive at Mars.
Only U.S., European, and Russian space agencies have sent an orbiter to Mars until now. That means India would join an exclusive club.
MOM is explicitly aimed at developing India's space capabilities, with all of its instruments built in India. The spacecraft is equipped with cameras, atmospheric gas sensors, and surface chemistry spectrometers, all providing India its own eyes on Mars.
Just as the two new spacecraft settle into operation, the comet Siding Spring will swing close by Mars on October 19. The comet will pass within roughly 82,000 miles (132,000 kilometers) of the red planet, about a third of the distance between Earth and the moon.
Dust trailing from the comet, traveling at 125,000 miles per hour (about 200,000 kilometers per hour), might pose a threat to spacecraft, so NASA has announced plans to park its Mars satellites on the far side of the planet during the passage. Afterward, the orbiters should enjoy a ringside seat to observe the comet's effects on the Martian atmosphere.
"The risk is really minimal," says MAVEN principal investigator Bruce Jakosky of the University of Colorado in Boulder. "We should learn a lot about the atmosphere from this natural experiment," he adds.
Mars has a lot more in store for explorers. On the planet's surface, NASA's Curiosity rover has finally reached the foothills of Aeolis Mons, or Mount Sharp, after a two-year journey to the place that was the true target of the mission.
Curiosity's analyses there are seen as the best chance yet for determining whether Mars ever possessed a habitable environment. A NASA Planetary Review Board panel over the summer criticized the Curiosity team for planning too few surface measurements of the foothills, with only eight scheduled on its currently approved extended mission.
Defending the mission plans, Curiosity mission science chief John Grotzinger of Caltech said at a congressional panel on September 3 that every analysis carries a risk of breaking the rover's drill, so taking fewer, better samples from a wide diversity of outcrops on Mount Sharp was a safer way to explore.
While Curiosity traverses some 5 miles (8 kilometers) of Martian mountain, NASA's Insight lander and Europe's ExoMars Trace Gas Orbiter mission, conducted with help from Russia, will reach the red planet in 2016. Insight will bore into Mars, looking for signs of seismic activity and subsurface heat.
More rovers will land on Mars starting in 2018, when Europe's ExoMars rover arrives, again with Russian help. The ExoMars will join the Curiosity rover in the search for signs of organic chemistry in the Martian past.
Finally, NASA's Mars 2020 rover will arrive in that year, equipped with new instruments atop a chassis copied from the Curiosity rover. The rover will also have tougher wheels—pointy rocks on Mars have chewed up the ones on Curiosity unexpectedly soon. The new rover will pick up the search for past habitable conditions on Mars at a new site, with sampling technology refined by Curiosity's discoveries.
"The orbital dynamics do put a damper on things for a few years," SpacePolicyOnline's Smith says, as Mars moves out of the optimum orbital sync with Earth after 2020. Mars orbits the sun once every 687 days, nearly twice as long as an Earth year. As a result, the planets are regularly out of perfect orbital alignment, and only every 26 months or so do month-long "windows" open for fuel-efficient paths for spacecraft to travel there from Earth.
But more muscular rockets, such as a heavy one now under development by NASA, might help make up for the difference, she adds, before and after the planets once more align.
Just as the Cold War saw a "moon race" ensue between U.S. and Soviet rocketeers, "a number of simultaneous Asian space races currently exist," writes Jeff Kingwell of Geoscience Australia's National Earth and Marine Observations Group, in Symonston, in the June Space Policy journal.
Tensions between China and Japan, for example, or between Asia's growing economies and older spacefaring ones, might drive future space endeavors in the same way as the race with the Soviets to the moon, Kingwell suggests.
Along those lines, a number of nations are talking about joining India in the Martian club. Both Russia and China, for starters, have announced plans for the kind of heavy-lift rocket under development by NASA, the kind needed to carry new nations to Mars:
China—In June, Ouyang Ziyun of the Chinese Academy of Sciences said his nation will land a rover on Mars by 2020. China put a rover on the moon last year called the Jade Rabbit, which is still in radio contact but otherwise moribund after its robotics failed.
Russia—Earlier this year, Victor Khartov of Russia's Lavochkin aerospace firm announced a plan to send a first probe to a Martian moon, Phobos, with the Boomerang mission for 2020. An earlier attempt, the Phobos-Grunt mission, failed after a launch mishap in 2012.
"What's happening is that a number of countries have gotten the technology to send probes to Mars—we have reached a point of international technological maturity," says Syracuse University's W. Henry Lambright, author of Why Mars: NASA and the Politics of Space Exploration. "Mars is a natural attractor for nations, as part of this bigger trend we call globalization."
"Mars is the 'big enchilada' for manned space [exploration], the natural target for people moving off the planet," says Smithsonian's space historian Launius. "That will always drive a lot of interest."
Right now, the U.S. has the most solid plans among space nations for sending astronauts to Mars in the 2030s, depending on funding, partners, and rockets. Elon Musk of SpaceX has also discussed sending colonists to Mars on a heavy version of his Falcon 9 rocket, famously saying, "I'd like to die on Mars, just not on impact," in a speech last year.
Ironically, Launius notes that Mars was a bit of a backwater in space exploration for a few decades, after the Viking missions of the 1970s found no signs of life there. NASA's 1997 Mars Pathfinder mission revived interest in the red planet and in the space agency's Mars program. A series of orbiters and rovers, notably Spirit and Opportunity, received tremendous public interest and revived NASA's prestige.
We may be coasting on that success, Lambright notes, pointing to recent budget cuts made to NASA's planetary science program, a $1.28 billion part of the $17.6 billion agency, have hit Mars exploration efforts.
Both houses of Congress this year requested more money for planetary science in NASA's budget than the Obama administration asked for, but that budget still awaits a vote. Within a long-term decline in NASA's share of government spending, now down to about 0.6 percent of the federal budget, the agency has dialed back its Mars plans.
On hold is the big-ticket item desired by both the space agency and planetary scientists, a Mars "sample return" mission. It would rocket back to Earth samples of Mars rocks, perhaps one scooped up by the Mars 2020 rover.
NASA chief Charles Bolden and others have suggested that manned Mars exploration will be too arduous for any one nation to undertake, requiring international cooperation. Some cost estimates for sending astronauts to Mars have ranged around $300 billion over 40 years.
As for the cornucopia of Mars missions, Lambright says the real question is whether they will lead to cooperation among spacefaring nations. NASA canceling participation in Europe's ExoMars missions over the past three years, citing costs, was a step in the wrong direction, he says.
"What we need to see is a point in time where national endeavors give way to more sustained international ones," he says. "We're not there yet, but maybe we will be sometime in the future."
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