NASA announces extension of nine spacecraft missions

Just before the spacecraft Juno finishes a fiveyear trip to Jupiter on Monday, NASA has decided to extend the missions of nine older robotic explorers that have lived beyond original expectations.

The agency announced the decision Friday, saying the nine still are producing bounties of observations for scientists.

Most of the extensions were expected. The New Horizons spacecraft, which flew past Pluto last year, already had been steered toward a new target, known as 2014 MU69, one of the small icy objects in the ring of debris beyond Neptune.

But one of NASA’s decisions, about the Dawn spacecraft orbiting Ceres, the dwarf planet in the asteroid belt, was somewhat of a surprise — as well as a disappointment to some working on the mission.

It was a bit unexpected because Dawn is low on fuel. “Less than a year ago, I would have thought it was ridiculous that the spacecraft would even be operating at this point,” said Marc D. Rayman, the chief engineer for the Dawn mission.

The Dawn spacecraft was designed to use four spinning wheels to pivot in different directions. But at its previous destination, the asteroid Vesta, two of the four wheels overheated and failed. At Ceres, the wheels stayed off, and the spacecraft used its thrusters instead to pivot.

In December, Dawn reached its lowest orbit, just 240 miles above Ceres. Rayman said he and his team had expected Dawn to exhaust its remaining propellant by March.

But they spun up the wheels again. That succeeded, cutting the use of the thrusters. That left enough fuel to contemplate doing something more.

On Thursday, Rayman’s blog made the announcement: Dawn would leave Ceres and head toward a flyby of a third asteroid, Adeona, in 2019. The posting was yanked. A member of Dawn’s social media team had mistakenly published an unfinished draft Rayman had started writing in case NASA selected that course.

On Friday, Rayman received word from officials at NASA headquarters they had decided on the other option proffered by the Dawn team: Dawn will stay where it is, continuing observations of Ceres.

Rayman said Dawn could continue until next spring, as long as the spinning wheels kept working.

The other missions receiving extensions are the Lunar Reconnaissance Orbiter and a flotilla of spacecraft at Mars: the Mars Reconnaissance Orbiter, the Mars Atmosphere and Volatile Evolution mission, the Mars Opportunity and Curiosity rovers, the Mars Odyssey orbiter, and NASA’s support for the European Space Agency’s Mars Express mission.

NASA officials periodically ask managers of the long-lived missions to justify the cost of their continued operations. Final decisions depend on whether NASA has enough money in its budget for all of them.