If you’ve been living in a cave, you may have missed the news on Tuesday that the New Horizons spacecraft successfully flew past Pluto.
But while the world was glued to images and telemetry returned by the spacecraft, another human-built machine had its own unique view of the flyby. Just two days before it took place (July 12, 2015), the European Space Agency’s (ESA) Rosetta spacecraft turned its cameras on the dwarf planet from comet 67P/Churyumov-Gerasimenko, capturing a distant image of the world.
The image is one of the few moments in history that one spacecraft in the Solar System has imaged another, albeit so small in this image that Pluto can hardly be seen. Nonetheless, it’s testament to how far our space exploration efforts have come.
Comet 67P, which Rosetta entered orbit around last August, is currently within the orbit of Mars. The distance between the two spacecraft when the image was taken was more than 5 billion kilometers (3 billion miles). Scientists on Earth had to scour through 20 Rosetta images to find the relatively tiny world that is Pluto, which is only two-thirds the size of our Moon.
Interestingly, both comet 67P and Pluto hail from the Kuiper Belt in the outer Solar System, and both have elliptical orbits around the Sun.
This new image of comet 67P released by ESA yesterday, showing its increased activity, was taken on July 7, 2015. ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0.
The images were taken with Rosetta’s OSIRIS camera, more commonly used to take high-resolution images of comet 67P, and the mission scientists were surprised it could see Pluto at this great a distance.
"After all, OSIRIS is not a telescope, but a camera system designed to study Rosetta’s comet from up close," said OSIRIS Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Research (MPS), Germany, in a statement.
In addition, the comet is now less than a month from its closest point to the Sun in its 6.4-year orbit, known as perihelion, which it will reach on August 13, 2015. As it gets closer, this means the comet is getting more and more active and expelling more debris. Dennis Bodewits from the University of Maryland, who worked on the images, compared looking at Pluto from the comet to watching it "through a blizzard."
Yesterday ESA released new images of comet 67P from the Rosetta spacecraft, with questionable timing, as there was the small competing matter of New Horizons returning the first ever close-up images from Pluto on the same day. Nonetheless, the ESA images give new views of several areas of interest on the comet, and reveal in greater detail some of its cliffs and other regions.
Perhaps next time, though, they should coordinate with NASA to ensure their images don’t get overshadowed by one of the most important moments in the history of space exploration.
Another image released yesterday was this view of the cliff-like areas in the regions known as Seth and Babi. It was taken on September 10, 2014, from 27 kilometers (17 miles). ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
This image shows the smooth region named Ash and exposed layers in Seth. It was also taken on September 10, 2014, from 27 kilometers (17 miles). ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.