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.
