European Space Agency's Mars Express
The Mars Express spacecraft's MARSIS collects data on the subsurface of Mars.
Credit: ESA, C. Carreau

Mars Express is the European Space Agency's first spacecraft built to explore another planet. The orbiter is still circling the Red Planet after more than a decade in space, but lander Beagle 2 lost contact with Earth in December 2003 before it reached the surface.

Among other achievements, Mars Express found methane in the Martian atmosphere, mapped the composition of polar ice and flew close to the Martian moon Phobos. 

Some of the instruments on Mars Express were originally intended for a mission called Mars 96, which failed shortly after launch on Nov. 16, 1996. Mars Express' high-resolution stereoscopic camera, and a mineralogical mapping spectrometer, both originated with Mars 96.

Mars Express would give these scientists a second chance to map Earth's neighbor. The mission got its name from its speedy development. The European Space Agency, seeking to reduce the size of the development team, gave primary responsibility to prime contractor Astrium.

The company used commercial off-the-shelf technology to finish the spacecraft faster. The orbiter cost just $195 million (150 million Euros) in 1996 prices.

Beagle 2 was a lander mainly developed by universities and companies in the United Kingdom, costing between $65 million and $80 million (40 to 50 million British pounds.) It was named after the HMS Beagle, a ship most famous for naturalist Charles Darwin's voyages in the 1830s. Darwin used his observations of nature on those trips as a basis for formulating his theory of natural selection.

Orbiter and lander launched successfully June 2, 2003, from Kazakhstan and arrived at Mars just six months later, in December 2003.

Beagle 2 was a particularly exciting part of the mission. It was scheduled to land on Mars and unfurl several petals of solar panels. Although the lander would remain in place, it had a robotic arm that could scoop samples and take pictures from its perch on the surface.

However, ESA lost contact with the lander after its scheduled touchdown date on Dec. 25, 2003. Controllers kept trying to hail the spacecraft, but came up empty. The mission was declared lost in February.

A government-private industry commission examining the loss of Beagle 2 did not find a single cause for the failure, which is common in spacecraft investigations.

Among other theories, the group said that the spacecraft likely had a problem with its landing air bag, which either collided with the main parachute or released the lander at the wrong time. Also, the commission said inadequate management, risk evaluation and funding contributed to the failure.

In January 2015, NASA's high-resolution Mars Reconnaissance Orbiter found the Beagle 2 lander, its rear cover and possible signs of a parachute on the Martian surface. It was about 3 miles (5 kilometers) from the center of its landing zone in Isidis Planitia.

The evidence demonstrated that Beagle 2 did make it to the surface, but didn't unfold itself correctly, according to the UK Space Agency.

Arabia Terra is one of the three equatorial regions where Europe¡¦s Mars Express PFS instrument detected both water vapor and methane concentration. The other two areas are Elysium Planum and Arcadia Memnonia.
Arabia Terra is one of the three equatorial regions where Europe¡¦s Mars Express PFS instrument detected both water vapor and methane concentration. The other two areas are Elysium Planum and Arcadia Memnonia.
Credit: NASA/JPL/Malin Space Science Systems

While Beagle 2 never began its mission, Mars Express carried on. The spacecraft made its first major discovery while its orbit was still being finalized. On Jan. 23, 2004, Mars Express spotted water ice and carbon dioxide ice at the Martian south pole. This meant the spacecraft already met its objective of finding water on Mars less than a month after reaching its destination.

Mars Express' team confirmed the water find in March 2004, saying the south polar cap is made up of 85 percent carbon dioxide ice and 15 percent at its center.

Weeks later, investigators came up with a second major discovery: finding methane on Mars. This excited scientists because methane is not expected to last long in the atmosphere.

This means there had to be some fuel for the methane on the planet's surface. Scientists theorized it might come from volcanoes, but said the matter required further study. There have been varying amounts of methane measured in Mars' atmosphere since then, including by the NASA Curiosity rover that arrived on the surface in 2012

Mars Express experienced a major hiccup with MARSIS, a radar instrument that was supposed to be deployed in April 2004. Last-minute simulations indicated there could be a "whiplash" effect on the spacecraft if the deployment was not done with care, so controllers waited until more tests could be performed.

ESA moved ahead with the deployment in May 2005, encountering one snag as part of an antenna did not lock as planned. MARSIS became operational that June.

One of the strengths of Mars Express is the higher resolution of its instruments. Camera pictures provided one of the best views of the Martian surface to date, allowing scientists to revisit the same areas and get more information. [Photos: Red Planet Views from Europe's Mars Express]

One famous example is the well-known "Face on Mars." First snapped by Viking 1 on July 25, 1976, the jumble of rocks and shadow on the Cydonia region appeared to form a human-like head. Conspiracy theorists and some members of the public became excited about the find despite NASA's cautions that the rocks only appeared as a face, and were not actually a face.

Viking 1, although it was a groundbreaking mission at the time, had a camera that pales with the capabilities of imagers today. Thus, researchers eagerly revisited Cydonia with newer spacecraft and better cameras, once they were available.

In 1998, NASA took another picture of the "face" using the Mars Reconnaissance Orbiter, revealing the face was a trick of shadow and poor resolution. Mars Express targeted the same area in 2001 and confirmed MRO's findings.

Mars Express' high definition camera also came in handy when scouting out the landing site for the Mars Curiosity mission. Its resolution of 330 feet (100 meters) per pixel helped planners reduce the planned landing site of the spacecraft, and helped narrow the landing zone.

Curiosity dropped to Mars just 1.5 miles (2.4 km) from the center of this target when it landed Aug. 6, 2012.

Mars Express' capabilities aren't just limited to surface features. MARSIS, which is now working fine, can map the interior of Mars as well as anything that happens to scoot nearby.

The spacecraft periodically flies near Phobos, one of the two tiny moons of Mars. During one pass in 2010, Mars Express became the spacecraft to get the closest to the moon. In 2013, it passed only 45 kilometers (27 miles) above the surface to learn more about the inner structure of Phobos, which may be mostly empty space. 

The lumpy moon is just 14 miles (22 km) in diameter. Some scientists, basing their findings on Mars Express data, believe the moon was formed after a comet or meteorite hit the planet in the ancient past. More observations were planned using the Russian Phobos-Grunt mission, but that spacecraft failed shortly after launch in November 2011.

In 2012, Mars Express spotted a possible ancient ocean on Mars: sediments on the planet's northern plains appeared to resemble what is seen on an ocean on Earth. The information came from more than two years of MARSIS data and buttressed previous observations showing possible Martian shorelines in the area.

To celebrate Mars Express' 10th anniversary at Mars in 2013, the team& released several global maps showing where minerals have been formed by water and where minerals have been distributed by volcanic activity. The maps also pinpointed areas that could be worthy of future landing missions, such as cliff flanks that may be laden with ice deposits.

Mars Express has been through several mission extensions and is now projected to work at Mars until at least 2018. “This will give the High Resolution Stereo Camera ... numerous additional opportunities to record the entire surface of Mars in high resolution, colour and, above all, in 3D,” the German Space Agency (DLR) wrote of the latest two-year extension in 2014.

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