Hope probe: What are the risks during Mars orbit entry attempt?

Spacecraft will try to be captured by the planet’s gravity at 7.30pm GST on Tuesday

The PSLV-C25 rocket carrying the Mars Orbiter Spacecraft blasts off from the launch pad at Sriharikota on November 5, 2013. Courtesy: Indian Space Research Organisation

A rocket carrying the Mars orbiter streaks across the sky after taking off from the east-coast island of Sriharikota, India, on November 5, 2013. Arun Sankar K / AP photo

On August 20, 1975, Viking 1 is launched by a Titan/Centaur rocket from Cape Canaveral in Florida to begin a half-billion mile, 11-month journey through space to explore Mars. The four-tonne spacecraft went into orbit around the red planet in mid-1976. Courtesy: Nasa

Viking 2 landed on Mars in September 1976 -- immediately following the first successful spacecraft landing on Mars by Viking 1 -- and was part of Nasa's early two-part mission to investigate the Red Planet and search for signs of life. Courtesy: Nasa

Technicians work on the construction of Beagle 2, a new Mars lander craft, on December 19, 2002. It was launched from a Soyuz-Fregat rocket in Kazakhstan and is part of the Mars Express mission but failed to land on the Red Planet. AFP

The Beagle 2 landing zone on Mars pictured about 18 minutes after the probe was scheduled to touch down on December, 25, 2003. A large dust storm reduced the quality of the image. The probe was launched by the European Space Agency but failed to land on Mars. AFP

The European Space Agency's ExoMars 2016 mission, combining the Trace Gas Orbiter and Schiaparelli landing demonstrator, launches on a Proton launch vehicle from the Baikonur Cosmodrome in Kazakhstan in 2016. Courtesy: Nasa

Taken by the Viking 1 lander shortly after it touched down on Mars, this image is the first photograph ever taken from the surface of Mars. It was taken on July 20, 1976. Courtesy: Nasa

Nasa's Viking 1 Orbiter spacecraft photographed this region in the northern latitudes of Mars on July 25, 1976, while searching for a landing site for the Viking 2 Lander. Credit: NASA/JPL-Caltech

More than half of previous missions to Mars have not succeeded due to reasons ranging from rocket failures after lift-off and failed landing attempts, to unsuccessful orbit entries.

At 7.30pm on Tuesday, the UAE’s Hope spacecraft will attempt to enter Mars' orbit, where it will remain for the duration of its mission to collect data.

It has already completed several key stages, including launch into space and vital course correction manoeuvres, in which the thrusters it will use to enter orbit were tested.

As the probe prepares to reach Mars, The National explores some of the potential risks associated with the orbit insertion attempt.

History of failures

There have been so many failed Mars missions that the planet was often called the "spacecraft graveyard" or "where spacecrafts go to die".

However, a lot of these unsuccessful attempts took place between the 1960s and 1990s.

The former Soviet Union – which encompassed what is today Russia, Ukraine and other countries – had the worst luck.

It launched several unsuccessful Mars missions in the 1960s.

They began with the Marsnik-1 spacecraft, which was meant to do a fly-by of the planet. It failed to reach Earth’s orbit and was destroyed.

Another seven attempts in the same decade and early 1970s all failed.

Reasons varied, from the spacecraft exploding after reaching Earth’s orbit, failed radio communication, going off course, to batteries dying or solar panels being lost.

In 1971, a Soviet Union spacecraft was finally placed into orbit. The lander that flew with the same mission, however, crashed.

US space agency Nasa managed to send two spacecrafts to Mars in 1969.

Between the 1970s to 1980s, the former Soviet Union attempted more Mars missions with no notable ones giving desired results. Most of their landing attempts failed.

In 1976, Nasa managed to send its Viking 1 and Viking 2 orbiters and landers to the Red Planet, both ending in success.

However, Nasa has also experienced failures. In the 1990s, mission control lost communication with the Mars Observer shortly before entering Martian orbit. The reason behind communication loss is unknown, but it was said to have been because of fuel tank damage.

Japan launched a mission to Mars in 1998, but the spacecraft failed to enter orbit.

Nasa’s Mars Climate Orbiter failed to enter orbit in 1999 because engineers programmed in the wrong measurements and it burned up in the atmosphere.

The 2000s was a more successful period for Mars missions, specifically orbiters. The European Space Agency managed to place the Mars Beagle 2 probe in orbit but the lander failed.

Nasa’s Spirit and Opportunity rovers were sent successfully. Both discovered key findings on dried river beds.

In 2016, ESA sent the Trace Gas Orbiter to Mars, which is still operational. The lander on the same mission failed to reach.

China tried launching a spacecraft to a Mars moon in 2011. It failed to reach Earth’s orbit after the Russian rocket that was carrying it failed. However, China’s Tianwen-1 orbiter and lander is expected to reach Mars on February 10, 2021.

In 2014, India became the only country to reach orbit in a maiden mission.

What chances does Hope probe have?

Statistics show more than half of Mars missions fail, but a lot of them were in the early era of space exploration when technology was not as advanced.

The success rate of placing spacecraft into Martian orbit grew significantly in the 2000s.

The risks that need to be considered now are thrusters not firing at the right time or failing entirely, fuel tank issues, going off course, missing the target orbit and doing a fly-by instead, damage to radio and losing communications, among many others.

The spacecraft has three pairs of Delta V thrusters. It cannot afford to lose more than one pair.

The orbit entry burn will run for 27 minutes, with a success signal expected at 8.08pm.