Cheers broke out today at the Jet Propulsion Laboratory’s mission control in Pasadena, California as pictures appeared from the EPOXI spacecraft’s closest approach to comet Hartley 2.
“These images are absolutely fantastic,” says Lori Feaga, an astronomer at the University of Maryland in College Park, who is on the mission’s science team. “We captured a perfect sun-lit side of the nucleus and a jet.”
The spacecraft—which previously visited and shot a projectile into comet Temple 1 as part of the Deep Impact mission—came within 700 km of Hartley’s nucleus, zipping by at 12.3 km/s.
With Hartley 2, probes have now visited five cometary nuclei. Feaga says that Hartley 2 shows similarities to other comets, such as having bright jets like Halley and smooth flows like Temple 1, but remains unique. For instance, Hartley 2 is the smallest and most active of the visited nuclei. Jets shooting off the surface cause it to spin randomly, which made predicting its position difficult, said team member Rich Rieber on NASA TV shortly before the flyby.
But all went according to plan during the approach, says Feaga, adding that the mission control room was full of smiling faces. Many there were eager to dig into the data once it came in from EPOXI, she says.
“It looks like we’ll have plenty of science to talk about for the next couple of years,” she says.
See also: Glimpsing a comet’s heart
Image: NASA/JPL
Updated [5:00 PM]: At a press briefing, several EPOXI team members spoke about the early scientific results gleaned from the spacecraft’s flyby.
So far the researchers have determined that Hartley 2 has rough terrain where jets are exploding from the surface while the center of the nucleus is covered in a fine, smooth material, said Jessica Sunshine, an astronomer at the University of Maryland. There are also locations with strange clumps of material, which might be remnants of previous activity, she added.
The Hartley images offer a unique opportunity because, for the first time, researchers can track jets to individual topographic features on the nucleus, said principal investigator Michael A’Hearn.
But A’Hearn emphasized that it will take time before the data is fully assessed and joked that, in the end, the mission “will increase our understanding of comets by at least 3 Hartley’s.”