NASA’s Kepler spacecraft is back from the dead and back to finding exoplanets, though it’s technically a new mission.
The Kepler space telescope was the agency’s most accomplished exoplanet hunter until last year when it suffered a devastating hardware malfunction. Two of the four reaction wheels designed to keep the spacecraft steady while it observes extremely distant and dim stars stopped working, effectively taking away Kepler’s ability to see clearly enough to spot possible exoplanets. Kepler looks for planets as dips in a star’s light. If it can’t see that star as a steady point of light to begin with, it can’t detect exoplanets. Still, losing the reaction wheels didn’t mean it was lights-out for the mission. Backlogged data continued to reveal exoplanets, but that was a finite store.
Now astronomers and engineers from NASA and Ball Aerospace have come up with a clever way to repurpose the space telescope for a new mission called K2 that will continue its hunt for worlds beyond our solar system. They figured out how to use pressure from sunlight as a “virtual reaction wheel” to help manage the spacecraft’s orientation in space. This K2 mission won’t just extend Kepler’s mission, it will also expand the search for life-harboring exoplanets in advance of the James Webb Space Telescope, a more advanced exoplanet hunter and successor to Hubble, that will hopefully launch before the end of the decade.
And it’s already paying off. Andrew Vanderburg, a graduate student at the Harvard-Smithsonian Center for Astrophysics, has already found a new exoplanet in publicly available data from a K2 test earlier this year. He confirmed its existence with ground-based measurements using the HARPS-North spectrograph of the Telescopio Nazionale Galileo in the Canary Islands.
The new exoplanet, “HIP 116454b,” is two-and-a-half times the diameter of Earth and orbits its star, which is cooler and smaller than the Sun, once every nine days. That means it’s far too hot to support life, but it’s still significant. Finding a small planet like HIP 116454b orbiting so close to its star makes K2’s scientific sweet spot different than Kepler’s. Kepler revealed that planets between the size and mass of Earth and Neptune are common. K2 might be able to find some much smaller bodies that are worth looking at again once the Jame Webb telescope is in space.
So we may find a tropical paradise, vacation-land version of Earth yet!