NATCHITOCHES, La., August 6, 2012 — NASA scientists learned that their latest Mars probe, Curiosity, had reached the end of its 8 ½ month voyage this morning at 1:32 AM, Eastern time. They learned about it 14 minutes after it happened, because Mars is currently 14 light minutes (about 156 million miles) from Earth.
Curiosity has been described as the most important Mars mission of the decade. It’s the first probe sent to Mars to look for signs of life in over 30 years. At $2.5 billion, it’s the most expensive robotic probe ever sent to another planet. At one ton, it’s the biggest and most sophisticated. Armed with its laser-powered ChemCam, it’s definitely the coolest.
The first image returned from Curiosity was a 64x64 pixel, black-and-white thumbnail of the probe’s wheel, followed by a higher resolution 256x256 image. The images show dust on the camera “window” and the lander’s shadow in the late afternoon at its landing site on Mars. Because Earth had already set below the horizon, the images were relayed to Earth by the Mars orbiter Odyssey. (Positioning Odyssey to do that was itself no mean achievement.) Color images in high definition will follow in about two days.
The huge distance from Earth to Mars meant that NASA scientists had no real-time ability to control or troubleshoot the landing. The rover’s flight computer had to do everything right the first time, and without human intervention.
Scientists, engineers and technicians at NASA’s Jet Propulsion Lab at Cal Tech broke into cheers and high-fives as Curiosity first slowed in the Martian atmosphere, slowed further as its parachute deployed at an altitude of seven miles and a speed of 900 miles per hour, then came to a near hover as the descent-stage rockets ignited, slowing the craft’s vertical velocity to under 2 mph. Curiosity was lowered by 25-foot tethers to the planet’s surface, an innovative and technologically ambitious “sky crane” procedure.
Dr. Charles Elachi, JPL director, declared this the most exciting Martian landing yet.
The sky crane was the solution chosen to place a robot the size of a car on a precise spot on the Martian surface. Earlier probes were dropped to the surface surrounded by giant airbags and bouncing to their final landing spot, or descended on rockets. Curiosity, weighing about a ton, was too large for the airbags. A descent on a traditional lander would have required powerful braking rockets on a large descent stage, leaving Curiosity stranded several feet above the ground. Getting it down from there would have been tricky and dangerous.
The dust on the camera window points to another problem with a lander; the powerful rockets would have raised huge amounts of dust.
The sky crane was itself a formidable challenge, but it worked as advertised. That isn’t a given when it comes to Mars probes.
The history of Mars probes has been filled with disappointment. Half of the 38 missions sent to Mars prior to 2011 failed. The record of failure was so dismal that writers joked of the “Mars Curse” and the “Great Galactic Ghoul.” Most of those failures were in earlier years of exploration, and most were Soviet. The American success rate was better, with 13 of 20 missions succeeding. Six of seven American Mars lander missions have succeeded. The vast distances to travel and engineering challenges put the many failures into perspective, though one particularly embarrassing American failure occurred when Lockheed Martin engineers confused metric and English units in their programming for the Mars Climate Orbiter. That vehicle was destroyed when it entered Mars’ atmosphere at a much greater than intended velocity.
Curiosity will search for chemical evidence of life, and for chemicals believed necessary to the formation of life. Beyond that, it will attempt to find evidence to explain why Mars lost most of its early atmosphere and water, becoming the cold desert planet it is today. Among the ten instruments it will use are an alpha-particle X-ray spectrometer (APXS), which fires alpha particles into rock and soil samples then looks at the X-rays produced to determine how they formed. The Sample Analysis at Mars (SAM) is a laboratory that takes up half the space on Curiosity. It includes a mass spectrometer, a gas chromatograph, and a laser spectrometer.
The ChemCam uses a laser to vaporize bits of the Martian landscape up to 23 feet away. The vapor can then be analyzed with a spectrograph to determine the exact composition of the rocks and minerals it came from. The ChemCam is located in Curiosity’s head. Just picture it!
Curiosity’s voyage to Mars was itself something of an experiment, measuring some of the dangers of a manned mission to that planet. Curiosity was hit by several solar storms - bombarded with charged particles – but suffered no damage.
Discovery of evidence for life on Mars would have huge significance to humanity. It would also raise some disturbing questions: If life arose on two planets in the same solar system, it is probably common throughout the galaxy. So why haven’t we detected signs of intelligence? Is intelligence rare, or is it ephemeral? If it’s ephemeral, what happens to it?
Another disturbing question has already been raised: What is the future of Mars exploration? The 2013 federal budget contains no money for Mars missions. NASA’s budget is already less than half a percent of the total federal budget, with Mars missions accounting for a very tiny part of that.
Curiosity is exciting at so many levels – for the science it can do, for the extraordinary engineering that went into it, for the idea of a one-ton robot armed with lasers prowling the Martian landscape. It’s the sort of project that can capture the imagination, showing kids that science, engineering and math are truly the path to the “final frontier” and are exciting subjects in their own right, and demonstrating and pushing the capacity of American science and technology.
It would be a huge shame if the opportunities opened by Curiosity were squandered. Now isn’t the time to kill Mars missions.
James Picht is the Senior Editor for Communities Politics and teaches economics at the Louisiana Scholars’ College in Natchitoches, La., where he went to take a break from working in Moscow and Washington. But he fell in love with the town and with the professor of Romance languages, so there he stayed. Now he teaches, annoys his children, and makes jalapeno lemonade. His undergraduate degree was in science, he worked at a major genetics lab, and when he watches updates on projects like Curiosity, he wishes he’d stuck with it. He tweets, hangs out on Facebook, and has a blog he totally neglects at pichtblog.blogspot.com.
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