It’s called perihelion. The time when Comet 67P makes its closest approach to the sun. ‘Close’ is relative in space. For Comet 67P, close is 115 million miles away from the sun. Here’s how that compares to the inner planets in our solar system.
– Mercury (35.98 million miles from the sun) – Venus (67.24 million miles from the sun) – Earth (92.96 million miles from the sun) – Mars (141.6 million miles from sun)
Last night at around 10 p.m. ET, Comet 67P – with Rosetta in tow – reached perihelion. Even with the vast distances, you can see the spike in activity on the comet’s surface. Check out the animation below. Look for the bright jet shooting towards the top left.
The increase in surface activity is expected to last through August. “Activity will remain high like this for many weeks, and we’re certainly looking forward to seeing how many more jets and outburst events we catch in the act, as we have already witnessed in the last few weeks,” says Nicolas Altobelli, acting Rosetta project scientist.
With surface activity spiking, the ESA’s Rosetta probe had to back away from the comet. The Rosetta probe is sitting between 325 km and 340 km away from the comet right now according to spacecraft operations manager Sylvain Lodiot.
Lodiot says the move was necessary so “Rosetta’s startrackers can operate without being confused by excessive dust levels – without them working properly, Rosetta can’t position itself in space.”
And there’s a lot of dust coming off the comet. The ESA estimates the comet is shedding 1000 kg of dust per second. That’s on top of up to 300 kg of water vapor every second. That’s nearly two bathtubs worth.
This is how much dust Rosetta was seeing in images captured on July 6 (released today).
It’s not just gas and dust either. Check out this boulder flying by the comet.
Mapping the rest of the comet
Perihelion is also giving scientists a fresh look at the comet’s southern hemisphere. Back in May, the seasons on the comet began to change. After more than five years in darkness, the southern hemisphere lit up as it entered a 10-month long summer.
Four new regions (seen below) were identified. This brings the total number of regions on the comet to 23. In keeping with the naming after Egyptian gods and goddesses, the four new regions are: Anhur, Khonsu, Sobek and Wosret.
Once the comet’s surface activity dies down, Rosetta will move back in closer to see how the comet’s surface has changed. “We also continue to hope that Philae will be able to resume its scientific operations on the surface and give us a detailed look at changes which may be occurring immediately surrounding its landing site,” says Nicolas.
Philae gave scientists at the ESA a wonderful surprise when it woke up in June. But, the lander quickly went silent again and has stayed that way for more than a month. Now, scientists’ priorities are getting data from the lander to Rosetta and conducting drill experiments.
“The problem is not power, but communications,” Aurelie Moussi from space agency CNES said in a webcast on Thursday according to Reuters. “We have to find something to do in a shorter duration.”
The communications issue wasn’t that much of a surprise as Rosetta repositioned itself to avoid dust and gas coming from the comet. But, it has been in range to receive communications from Philae since August 11th. So far, only silence. Data from the last communications received from Philae showed one of its transmitters is broken, and two receivers were malfunctioning.
Want to learn more about Rosetta and the comet? Check out the Google Hangout with several Rosetta mission experts from this morning.