The Rosetta spacecraft woke from 31 months of hibernation like a bear waking from its long winter’s nap. The Rosetta spacecraft’s on-board lander, Philae, is a European Space Agency probe designed to land upon a comet this coming November. On Monday, the Rosetta spacecraft’s pre-programed alarm woke the slumbering spacecraft and sent out a signal to indicate that it was finally awake and ready to commence the next stage of its mission.
The day was “tense” according to Fred Jansen, who is the manager of the Rosetta mission, but he and the rest of the European Space Agency (ESA), he stated, are “delighted to have our spacecraft awake and back online.”
The Rosetta spacecraft embarked upon its mission to land on Comet 67P/Churyumov-Gerasimenko 10 years ago. Rosetta’s onboard lander, Philae, if successful, will be the first probe to ever land upon the surface of a comet.
In June 2011, ESA scientists in Germany put the Rosetta spacecraft into a deep sleep, shutting down almost all of its systems. The reason they did this is because the Rosetta spacecraft could no longer use its solar array to generate enough power, as it had journeyed too far away from the sun.
On Monday, the Rosetta spacecraft’s pre-programmed alarm reactivated it because the spacecraft’s orbit had once again brought it into close enough proximity to the sun so that Rosetta could use its solar array.
NASA’s Goldstone ground station, in California’s Mojave Desert, detected the signal that the Rosetta spacecraft sent out. The signal was also received by the Deep Space Network (DSN) ground station at Canberra, Australia. It’s one of three such ground stations.The other two are in Madrid, Spain, and La Canada Flintridge.
Previous comet missions, according to Rosetta mission scientist Matt Taylor, “have been flybys.” But, not so with the Rosetta spacecraft mission, which is designed to collect data for longer than a year and provide important information to help ESA scientists learn more about the role of comets “in the formation of the solar system.”
The previous flybys include, most famously, the US Stardust probe, and Europe’s Giotto. The US Stardust probe collected and brought home grains from the wake of a comet, and Giotto got within 120 miles away from the surface of a comet.
The Rosetta spacecraft overslept by more than eight hours, but when it finally sent back a signal to announce that it had awakened, the normally relatively reserved ESA scientists were ecstatic. Matt Taylor, for example, punched the air in a show of exuberant celebratory victory, and shouted “We got it!”
There is a lag in time of 45 minutes for a signal sent from Earth to get to the Rosetta spacecraft, and 45 additional minutes for scientists to get back a response.
When the signal from the Rosetta spacecraft didn’t arrive on time, according to Taylor, the mood of the ESA scientists in the control center quickly grew tense. The more time passed by without the scientists receiving a signal, the more worried they became.
Over the course of the next few weeks, ESA scientists will gradually reawaken the Rosetta spacecraft more fully, and make sure that its 21 instruments are functioning properly. 11 of the instruments are aboard the Rosetta spacecraft, while 10 are in the Philae probe. Besides checking out the instruments, the scientists will also send out updates to the instruments.
The Rosetta spacecraft is still 5 million miles away from Comet 67P/Churyumov-Gerasimenko. It won’t draw close to the comet until August, when the Rosetta spacecraft will map the comet’s surface, analyze the cloud of debris and gas (coma) of the comet, and measure how much gravity it exerts prior to sending forth the Philae probe which will land upon it in November.
This coming May, the Rosetta spacecraft will send back preliminary photos of Comet 67P/Churyumov-Gerasimenko taken from two million kilometers away. Final positioning readouts will be sent to the Rosetta spacecraft. Then, it will begin its final burn and orbit the comet in August, at a height of only 15 miles.
The 100 kg Philae probe will attach itself to Comet 67P/Churyumov-Gerasimenko much as Captain Ahab attached himself to Moby Dick, with harpoons and screws (though Ahab accomplished the task vis a vis the whale minus the screws). Then, Philae will initiate drilling operations and analyze the composition of the comet.
As Comet 67P/Churyumov-Gerasimenko travels further and further away from Earth, the Rosetta spacecraft’s solar cells will become increasingly less efficient. However, ESA scientists think that the Rosetta spacecraft and Philae probe will be able to send back good data for several years before they eventually lose contact.
Will the Rosetta spacecraft be able to unlock and decipher mysteries of comets and the origins of the universe, much as the carved stone, the Rosetta Stone which the project is named after, was used to decipher Egyptian hieroglyphics? If the Rosetta spacecraft and Philae probe continue to be successful, we might begin unlocking and deciphering many of the mysteries of comets this coming November.
Written by: Douglas Cobb