Marsnik 1/NASA

1960
Mission: Korabl 4 (Marsnik 1)
Agency: USSR
Game Plan: Mankind's first attempt to fly past and photograph Mars.
Success? No. The Russians began the race to Mars with Marsnik 1. The missile-based probe got 75 miles off the ground before a rocket conked out, sending it crashing back to Earth.
  
  

Mariner 3

1964
Mission: Mariner 3
Agency: NASA
Game Plan: The United States entered the space race with the Mariner missions. Of nine prototypes tested, five were launched. The first was Mariner 3, with a mission to fly by the planet and take pictures and measurements.
Success? No. A dangling shield doomed the mission. The probe was supposed to shed a shield after it made it through the scorching atmosphere. But the shield failed to jettison and dragged the probe off course.
  
  

The surface of Mars, 1969

1964 - 1969
Mission: Mariner 4, 6 and 7
Agency: NASA
Game Plan: Three more shots to get a U.S. probe to Mars.
Success? Yes. Mariner 4, getting within 6,117 miles of Mars, photographed a large crater and confirmed the existence of a thin, carbon-dioxide rich atmosphere. Mariner 6 and 7, identical craft launched in early 1969, got as close as 2,131 miles and determined the size of Mars.
  
  

Olympus Mons volcano

1971
Mission: Mariner 9
Agency: NASA
Game Plan: To orbit the Red Planet, instead of just flying by.
Success? Yes. A dust storm covered the entire planet during Mariner 9's first month in orbit, hiding all but Mars' largest volcanoes. When the storm finally cleared, the probe circled for 10 months, measuring Martian gravity and atmosphere density. The probe sent back more than 7,000 pictures, giving scientists their first look beneath the atmosphere at a planet with gigantic volcanoes and a 3,000-mile-wide canyon.
  
  

Viking 2 at Utopia Planitia

1975 - 1980
Mission: Viking 1 and 2
Agency: NASA
Game Plan: For the space race's next amazing feat, a landing on Mars. A 1973 Russian mission, Mars 6, actually did land on the surface, but lost communication after just a few seconds.
Success? Yes. Viking 1 landed on Mars on July 20, 1976, exactly seven years after Neil Armstrong made his giant leap, and Viking 2 landed on the opposite side of the planet two months later. Both Viking spacecraft took thousands of images and measured atmospheric conditions. But perhaps most important, they collected soil samples with a scoop, put them through chemical analyses and sent the results back to Earth.
  
  

Phobos 1

1988
Mission: Phobos 1 and 2
Agency: USSR
Game Plan: In the 28 years since Marsnik 1, the Russians attempted 11 separate missions to Mars — all failures. The Phobos orbiters were supposed to study the sun and interplanetary space on the way to Mars, set-up in orbit and then take pictures of the moon Phobos.
Success? No. Two months into Phobos 1's flight, ground controllers accidentally deactivated the software that adjusted the craft's altitude. Its solar panels now turned away from the sun, Phobos 1 could not recharge its batteries. Phobos 2 did get into orbit and sent back some preliminary data, but after two months, its onboard computer broke and communication was lost. Russia tried, and failed, once more in 1996, with Mars 96.
  
  

Sojourner on Mars, 1997

1996
Mission: Mars Pathfinder
Agency: NASA
Game Plan: Past missions had just plunked down on the rocky Martian surface. But the Pathfinder — a six-wheeled mobile robot — was made to explore.
Success? Yes. Once the pyramid-shaped Pathfinder made it to the surface — the first to do so since the Viking missions 20 years before — it set up a weather station and released its six-wheeled Sojourner rover to explore. Scheduled to last just 30 days, both the lander and Sojourner sent images and data back for almost three months before contact was lost.
  
  

Mars Climate Orbiter

1998
Mission: Mars Surveyor '98
Agency: NASA
Game Plan: A two-part program, with an orbiter and lander. Both were meant to study long-term Martian weather and climate changes, with the lander collecting samples near the southern polar ice cap.
Success? No. What amounts to a high-school math error sealed the orbiter's fate. Engineers had failed to convert rocket thrust calculations provided in English units into NASA's standard metric units. The orbiter approached Mars at too low an altitude and was lost. The program's polar lander also crashed; a faulty software system made the rockets turn off too soon.
  
  

The Melas Chasma

2001
Mission: 2001 Mars Odyssey
Agency: NASA
Game Plan: Rainbow bright! Odyssey had infrared technology onboard to capture heat readings day and night.
Success? Yes. The probe is still in orbit, and its images help scientists determine soil composition through temperature patterns.
  
  

Beagle 2

2003
Mission: Mars Express and Beagle 2
Agency: European Space Agency (ESA)
Game Plan: The ESA's first attempt to get in the Mars game, the Express was designed to capture geologic features of Mars in more detail than ever before, and drop a tiny rover, Beagle 2, onto the surface.
Success? Partial. The orbiter is still collecting data, but Beagle 2 lost contact shortly after it separated from the orbiter. Maybe they should have sent a golden retriever.
  
  

Microscopic Martian "blueberries"

2003
Mission: Mars Exploration Rovers, Spirit and Opportunity
Agency: NASA
Game Plan: Like the 1996 Pathfinder, Spirit and Opportunity were built to explore Mars, take pictures and collect samples with two, six-wheeled rovers. But while the Pathfinder could go distances of only a few meters, Spirit and Opportunity could go thousands.
Success? Bumpy, but yes. In April 2004, the Spirit and Opportunity rovers were dropped onto opposite sides of Mars and have been roving in and out of bedrocks and impact craters ever since. Most notably, Opportunity discovered after two months what ET-advocates had been hoping for: definitive evidence that water once flowed, providing a hospitable environment for potential Martian life.
  
  

The Mars Reconnaissance Orbiter

2005
Mission: Mars Reconnaissance Orbiter
Agency: NASA
Game Plan: After the Opportunity rover confirmed the existence of water on the surface of Mars, the Reconnaissance orbiter seeks to find out the history of water on Mars, particularly if it was around long enough to sustain hospitable life. A surveyor camera – the largest for its time – is looking for any shorelines of seas and lakes, as well as identify rock obstacles that could jeopardize future missions.
Success? Yes. Despite a few recent glitches in the software, the Reconnaissance orbiter has returned unprecedented images. Earlier in 2007, mineral deposits were spotted along faults and fractures, increasing speculation that liquid or gas may have flowed along cracks deep underground, providing habitats for microbial life. It will remain in orbit until 2010.
  
  

Phoenix Mars Lander

2007
Mission: Phoenix Mars Lander
Agency: NASA
Game Plan: Armed with a portable laboratory and an "oven" to heat soil samples for further examination, the Phoenix will survey Mars' icy northern pole. During the 150-day mission, Phoenix will dig trenches up to 1.6 feet deep into the layers of the water ice with its robotic arm. These layers are thought to contain organic compounds essential for the existence of life.
Success? To be determined. The Phoenix — named after the resilient, mythological bird — arrives at Mars on Sunday.