After a brief scare, the Kepler spacecraft is running safely once more.
The scare came on April 7 during a scheduled contact with the spacecraft. At that time, mission operations engineers discovered that Kepler had set itself to Emergency Mode (EM), the spacecraft’s lowest operational mode. This mode of operation is fuel intensive.
The EM event began hours before the scheduled contact with NASA. The mission operators were going to maneuver Kepler so that it would point toward the center of the Milky Way.
Once oriented, Kepler would continue its search for other planets through “gravitational microlensing.” Through gravitational microlensing, the spacecraft can detect warped or deflected light caused by a large body.
The report on April 7 was the first time in seven years that Kepler went into EM. NASA’s mission operations engineers are still unsure about what forced the change.
“An investigation into what caused the event will be pursued in parallel, with a priority on returning the spacecraft to science operations,” Sobeck said in a statement released on April 8.
On Sunday, April 10, Kepler missions operations engineers successfully recovered it from Emergency Mode (EM).
“On Sunday morning, the spacecraft reached a stable state with the communication antenna pointed toward Earth, enabling telemetry and historical event data to be downloaded to the ground,” Charlie Sobeck, Kepler and K2 mission manager, said in a statement on April 11.
Once NASA receives the data, it will assess Kepler’s on board systems to ensure it is capable of returning to science mode and continuing its search for other planets.
Kepler is a space telescope that searches for and identifies “exoplanets,” or planets that orbit other stars. It identifies these planets by noting changes in brightness as planets pass between the telescope and their host star.
Kepler, currently 75 million miles from Earth, has identified 4,696 exoplanet candidates, with 1,000 confirmations. In May 2013, malfunctions in the spacecraft’s reaction wheels forced the Kepler mission operators to constrict the scope of Kepler’s search capabilities.
The new mission, called K2, still seeks out exoplanets but on a more limited scale. It also studies various cosmic objects and phenomena, such as supernovae, asteroids and comets. The Kepler spacecraft will continue this study until 2017 or 2018.
The distance between Kepler and Earth makes communication slow, making it more challenging to make adjustments.
“Even at the speed of light, it takes 13 minutes for a signal to travel to the spacecraft and back,” Sobeck said.
Even so, Sobeck credits “the quick response and determination of the engineers” with Kepler’s recovery.
Observations will continue as engineers continue checking Kepler’s health. If all goes according to plan, Kepler will continue observing the Milky Way’s center until July 1.