Reaching Mars is a hard and unforgiving endeavor, with little room for error. More than two-thirds of the 40-odd missions launched toward Mars have been lost due to failed components, rocket glitches or grievous errors that sent probes crashing into the martian surface or missing the planet altogether.<br> <br> With NASA getting set to land its next Mars rover Curiosity on Aug. 5, here’s a look at the best – and worst – Mars landings of all time. <br> <p>-- Tariq Malik, SPACE.com Managing Editor
Mars 2, a lander built by the former Soviet Union, has the double-edged distinction of being the first human-built object ever to touch down on the red planet. Launched in tandem with its sister craft Mars 3 in 1970, the spherical 1-ton Mars 2 lander was about the size of a kitchen stove and designed to parachute to the martian surface and use rockets for final braking. <br><br> Despite surviving the long trip the Mars – a major feat in itself- the probe crashed into the martian surface somewhere west of the Hellas basin while a major dust storm churned across the planet.
Like its sister craft Mars 2, the Soviet Union’s Mars 3 landing mission is a marriage of engineering accomplishments and inexplicable failure. The lander appears as the conical top of the Mars 3 orbiter mothership in this image.<br><br> The probe launched in 1970 and landed successfully on Dec. 2, 1971 in the martian uplands of Terra Sirenium after descending through the same dust storm that thwarted its Mars 2 predecessor (see No. 10). But 20 seconds after beginning its first photographic scan, Mars 3’s TV signal went silent for good.
On Christmas Day 2003, the British-built Beagle 2 lander plummeted through the martian atmosphere with the hopes of Europe on its tail, only to vanish without a trace.<br><br> Shaped like an oversized pocket watch, Beagle 2 hitched a ride to the red planet aboard Europe’s Mars Express orbiter, but <a href=“http://www.space.com/missionlaunches/051220_ap_beagle2_found.html”>crash landed</a> on the planet rather than bouncing to a stop with airbags. A lower than expected atmospheric density may have caused the probe’s parachute and airbags to deploy too late, an investigation later found.
British and Russian researchers aren’t alone in sending space probes to Mars only to have them fail at the end. NASA’s Mars Polar Lander, launched in January 1999, crashed just before landing near the planet’s south pole in December of that year due to an engineering flaw.<br><br> Some of the probe’s leftover tools and equipment were used to build NASA’s new Mars lander, Phoenix, due to land in May 2008.
The first successful landing on Mars came on July 20, 1976, when NASA’s Viking 1 lander touched down in Chryse Planitia (The Plains of Golf). The massive 1,270-lb (576-kg) lander dropped from an orbiting mothership to make a three-point landing using a parachute and rocket engine.<br><br> Viking 1’s three biology experiments found no clear evidence of Mars microbes. The lander was powered by a plutonium decay-powered radioisotope thermoelectric generator and went silent on Nov. 11, 1982, six years after completing its initial 90-day mission.
Fresh off the success with Viking 1, NASA landed on Mars again on Sept. 3, 1976 with Viking 2.<br><br> Sister ship to Viking 1, Viking 2 set down on the broad, flat plains of Utopia Planitia, where it snapped photos of morning frost and – like its predecessor – found a sterile soil that held no clear evidence of microbial life. The lander shut down in 1980.
On July 4, 1997, NASA celebrated U.S. Independence Day in style by landing the first mobile probe on the red planet.<br><br> The Mars Pathfinder Lander used a parachute and airbags to land on the red planet, and then deployed Sojourner – a small, six-wheeled rover the size of a microwave oven that explored nearby terrain. A complete success, the mission ended with a final transmission on Sept. 27, 1997.
The success of Mars Pathfinder and its Sojourner rover led to a larger, bolder Mars landing on Jan. 4, 2004, when NASA’s golf cart-sized Spirit rover bounced to a stop inside the broad Gusev Crater.<br><br> Spirit spent more than six years – far beyond its initial 90-day mission – exploring Mars before going silent in March 2010.
The twin of NASA Spirit rover, the robotic explorer Opportunity is alive and well more than eight years after its Jan. 25, 2004 (ET) landing.<br><br> Opportunity landed on the flat plains of Meridiani Planum, which sits on the side of Mars opposite Gusev crater. Amazingly, the rover landed in a small crater, where a nearby outcrop contained evidence that the region was once soaked with water in ages past. The rover has since explored more than 20 miles on Mars and is now exploring the rim of a huge crater called Endeavour.
Phoenix, NASA’s most recent Mars lander, landed on May 25, 2008 and used some spare instruments and equipment salvaged from the lost Mars Polar Lander project.<br><br> The solar-powered spacecraft landed near the Martian north pole, where it used a robotic arm-mounted scoop to dig for buried water ice and onboard instruments to determine whether the region may once have been habitable for microbial life. The mission lasted about seven months before the harsh Mars winter ended the lander's mission.
NASA's next Mars rover is its most ambitious yet. <br><br> The Mars Science Laboratory Curiosity launched toward the Red Planet in late November 2011 and is slated to land in Mars' Gale Crater on Aug. 5 to begin a two-year mission of exploration. <br><br> The landing won't be easy, however. The 1-ton rover will be lowered to the surface on cables by a rocket-powered sky crane, a maneuver that has never been attempted before on another planet.
