NASA’s Daybreak spacecraft, seen right here in orbit round Ceres, will stay there via the remainder of its mission, more likely to finish within the second half of 2018. Credit score: NASA/JPL-Caltech
WASHINGTON — NASA has granted a second, and sure last, extension for the Daybreak mission, permitting it to proceed observations of the dwarf planet Ceres via 2018.
The extension, introduced by the company Oct. 19, implies that the spacecraft is not going to depart orbit round Ceres, the biggest object in the principle asteroid belt, to go to one other asteroid, an choice venture scientists mentioned earlier this 12 months was into account.
The newest extension, the company mentioned, might enable the spacecraft to make high-resolution observations of Ceres. The mission group is finding out choices to position Daybreak into an elliptical orbit that will deliver it inside 200 kilometers of the floor of Ceres. Beforehand, the spacecraft got here no nearer than 385 kilometers.
These shut approaches, NASA mentioned in an announcement, would enable higher measurements of the uppermost layer of the dwarf planet’s floor utilizing the spacecraft’s gamma ray and neutron spectrometer, together with figuring out how a lot ice it accommodates. Daybreak may even gather high-resolution pictures and spectra on these shut approaches.
Daybreak’s lifetime is restricted by its provide of hydrazine gas, which the spacecraft has to expend for perspective management after the failure of three of the spacecraft’s 4 response wheels. Daybreak’s present orbit, which retains the spacecraft between 5,100 and 38,300 kilometers above Ceres, permits it to be “very frugal with its treasured hydrazine,” mentioned Marc Rayman, chief engineer for the mission, in a Sept. 27 assertion. “When the hydrazine is expended, the mission will finish.”
With the proposed shift to a decrease orbit, Daybreak will expend extra hydrazine. The spacecraft ought to be capable to function till a while within the second half of 2018. That may enable observations of Ceres because it passes perihelion, the closest level in its orbit to the solar, in April 2018.
This extension, although, guidelines out proposals to ship Daybreak out of orbit to a different asteroid. Venture officers proposed such an prolonged mission within the senior overview of planetary science missions in 2016, which might have despatched Daybreak on a flyby of the asteroid Adeona in 2019. NASA rejected that proposal, concluding that Daybreak would supply extra science by remaining in orbit round Ceres.
As that preliminary prolonged mission got here to an finish in June, venture officers once more prompt they have been contemplating a proposal to ship Daybreak to a different asteroid. “It’s an choice,” Carol Raymond, deputy principal investigator for Daybreak on the Jet Propulsion Laboratory, mentioned at a June 13 assembly of NASA’s Small Our bodies Evaluation Group. She didn’t present further particulars about that choice.
Daybreak, a part of NASA’s Discovery program of low-cost planetary science missions, launched in September 2007. Utilizing an ion propulsion system, it entered orbit round the principle belt asteroid Vesta in July 2011, remaining in orbit there earlier than leaving for Ceres, arriving there in March 2015.
NASA mentioned the prolonged mission shall be designed in order that, when Daybreak depletes its hydrazine, it will likely be in a steady orbit round Ceres with no danger of crashing into the dwarf planet.