Comet-chaser Rosetta’s mission comes to an end next week – with a literal bang. More than 12 years after launch, the European Space Agency’s probe will drop and crash onto the surface of Comet 67P/Churyumov–Gerasimenko, scanning its surrounds and beaming information to Earth until we inevitably lose contact.
It will be the latest in a long line of kamikaze space missions. Destroying an expensive probe may seem like a gigantic waste of time and money, but they are often unable to measure some aspects of a planet, asteroid or comet without getting up close and personal.
Sometimes crashing a spacecraft is the only way to glean particular information from a celestial body.
Besides, terminal plunges into the hostile atmosphere of, for instance, Jupiter, also protects precious moons from biological contamination.
So let’s take a look at a few memorable suicidal spacecraft and what they told us in their final moments.
Launched in 1959, Luna-2 was the first spacecraft to land on the moon, and the second spacecraft to be launched in the Soviet Union’s Luna program.
Its crash landing east of the vast lava plain Mare Imbrium, and the impact of the third stage of its rocket on the moon, suggested that the moon had no noticeable magnetic field.
NASA’s Ranger 7 was designed to transmit images in the final minutes before it crashed into the moon in 1964.
It sent pictures showing the moon was very rocky and strewn with debris, but suggested that some areas were smooth enough – and potentially hard enough – for humans to land safely.
Lunar Crater Observation and Sensing Satellite (L-CROSS) and Lunar Reconnaissance Orbiter were sent by NASA on their way to the moon on 18 June, 2009.
Crashing L-CROSS would produce a plume of buried lunar material. This could be analysed for water, hydrocarbons and other hydrated materials. And when the craft’s upper stage smashed into the surface, it confirmed the presence of pure ice, as well as methane, ammonia, hydrogen gas, carbon dioxide and carbon monoxide, believed to be the remnants from a comet impact.
The Venus-mapping probe was deployed in May 1989 by NASA and reached Venusian orbit 15 months later, spending four years dutifully snapping images of Earth’s neighbour.
In September 1994, it was commanded to plunge into the Venusian atmosphere to gather information on its upper layers. In mid-October, radio contact was lost after the probe was likely torn apart.
Carrying a probe to drop into Jupiter’s atmosphere, NASA’s Galileo spacecraft took off in October 1989, whizzed round Venus and Earth and arrived at the Jovian system in December 1995.
After dumping the probe (which found the atmosphere was hotter and denser than expected), Galileo spent eight years keeping Jupiter and its moons company. But by September 2003 its mission had drawn to a close, and was given orders to plunge into the atmosphere too.
Ebb and Flow
The twin spacecraft were given their orders in December 2012 after a year mapping the moon’s gravity as part of NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission.
The crash target was chosen far away from moon landing sites to help preserve their cultural heritage.
NASA’s Mercury Surface, Space Environment, Geochemistry and Ranging spacecraft, or Messenger, was sent to the planet closest the sun (via Venus) in 2004, where it slotted into Mercury orbit in 2011.
After running out of propellant, Messenger entered into its terminal orbit in late 2014. It continued to snap images and sniff the planet’s chemistry, finally crashing onto the surface of Mercury on 30 April 2015.