Science managers have conceded failure in attempting to restore the Kepler Space Telescope to full functionality, and will focus on what the telescope can do with only two of its four reaction wheels working.

Designed to find extra-solar planets by detecting the faint flicker in light from distant stars when planets pass in front of them, Kepler lost the pointing accuracy it needs for the task when a second wheel failed in May.

A system-level performance test Aug. 8 concluded the situation can’t be fixed, and mission managers have turned their attention to evaluating responses to an Aug. 2 call for proposals to use the spacecraft with its two surviving wheels and thruster system for attitude control.

The mission science team will also continue evaluating data from its prime mission and a follow-on that started in November 2012 to confirm planets in the “Goldilocks” zone where temperatures permit liquid water.

“Now, at the completion of Kepler observations, the data holds the answer to the question that inspired the mission: Are Earths in the habitable zone of stars like our sun common or rare?” says William Borucki of Ames Research Center, principal investigator for the missions.

NASA says any follow-on mission will compete with other astrophysics missions for funding, which would last two years if available.