Kepler, the spacecraft on the hunt for Earth-like planets, may have  reached the end of its mission.

NASA, on a call Wednesday, sang the mission’s praises, highlighting the variety of discoveries and reams of data the program had produced. But hanging in the air was the question of whether the mission could continue in the wake of a failure of one of the observatory’s reaction wheels.

“I don’t think I’d be a pessimist here,” said William Borucki, Kepler science principal investigator at Ames Research Center in California. ”I really wouldn’t write it off at this point.”

Kepler costs $20 million a year with a $600 million operating budget to date. It has delivered reams of data — terabytes worth — that, according to Burocki, is anticipated to be used for at least a decade.

The hunt for Earth-like planets far predates Kepler, of course. As The Post’s Joel Achenbach put it in April:

The first exoplanet — a planet outside our solar system — was found in 1995, and since then a frenzy of planet-hunting using a variety of techniques has produced hundreds of discoveries. Extrapolating from what has been observed so far, astronomers increasingly think that planets are commonplace in the universe, and that our galaxy alone could have billions of planets in life-friendly orbits.

In the meantime, regarding Kepler’s future, we are left to wait as NASA analyzes the data regarding the spacecraft’s condition.

Joel Achenbach contributed to this report.

READ: NASA’s Kepler space telescope malfunction may end hunt for planets