The European Space Agency's Rosetta probe has been orbiting Comet 67P/Churyumov-Gerasimenko for over two years. During that time, the probe has taken thousands of measurements, taken high-resolution photos, and even sent a small lander to the surface of the comet.
But now, it's almost time to say goodbye.
The Rosetta probe is set to end its mission by crashing into the comet later this month, and the team will turn back its focus back to Earth to analyze that huge amount of data the probe has gathered during its historic mission.
The probe was launched in March of 2004, arriving at Comet 67P in August 2014. The probe provided researchers on Earth with the first close-up view of the comet's irregular and asymmetrical structure. The researchers hoped the particularly ancient comet would provide insight into how the solar system formed.
And the probe delivered.
“Rosetta has returned reams of data we are only beginning to analyze,” Mark McCaughrean, a senior science adviser at ESA, told the Guardian. “It is transforming our understanding of the way the solar system was put together.”
According to the ESA's website, the decision to end the Rosetta mission comes out of necessity. The comet is heading out towards Jupiter and away from the sun, leaving the solar-powered craft with a dubious power supply. In early October, the problem would become even worse as a solar conjunction would put Earth and he comet in between the probe and the sun. While the team considered putting the probe into hibernation, 12 years of space travel (two of which left the probe in the tail of a comet) has taken its toll, making it far from sure that Rosetta would be able to "wake up" after a period of hibernation.
Therefore, on September 29th, the probe will undergo a controlled burn to cancel out the orbital velocity about 20 kilometers (12.43 miles) from the comet's surface. Rosetta will then fall towards the comet, according to Phys.org. The descent will be slow due to the small gravitational pull of the comet – about walking speed – but the velocity will likely be enough to damage the Rosetta on impact, making the descent the last chance for gathering data on the comet.
The probe will crash into a region of the comet known as Ma’at, according to the ESA. Ma'at is full of active pits where the dust jets of the comet originates. The region also contains small structures known as "goosebumps," which are thought to be signatures of early "cometesimals" that created the comet billions of years ago.
“We will go down very slowly, under a meter a second, so we can take as many high-resolution pictures and spectrographic measurements as possible,” McCaughrean told the Guardian. “With luck we will get some very interesting data.”
Even if Rosetta survives the descent, it will not be able to receive enough light on the comet's surface to function. Without power, the probe will stop transmitting forever.
"That will be the end of Rosetta,” said McCaughrean to the Guardian. “It will be an emotional moment. This has been a wonderful mission and a great team effort.”