The search for planets that might support life like that found on Earth, now being carried out by the large reflector telescope on board NASA’s Kepler spacecraft, is in jeopardy, because one of the reaction wheels that keep the spacecraft pointed has malfunctioned, NASA reported Wednesday:
… the data appear to unambiguously indicate a wheel 4 failure, and that the team’s priority is to complete preparations to enter Point Rest State. Point Rest State is a loosely-pointed, thruster-controlled state that minimizes fuels usage while providing a continuous X-band communication downlink. The software to execute that state was loaded to the spacecraft last week, and last night the team completed the upload of the parameters the software will use.
This is the second reaction wheel that has malfunctioned on the spacecraft since it was launched in March 2009. Analyzing the problem with wheel 4 could take weeks to months, and at this time, officials seem to think the spacecraft has enough fuel to operate in Point Rest State until they can determine what ultimately caused the malfunction.
Kepler orbits the sun at about the same distance as Earth. Its mission is to search for planets that orbit stars in our galaxy and have features in common with Earth. The hypothesis is that if planets are like Earth and their “suns” are like our sun, those planets may be able to support life.
The way Kepler looks for possible planets around other stars is by pointing its large mirror at those stars and observing fluctuations in the brightness of the stars when possible planets pass in between the star and Kepler’s telescope.
When a planet partially blocks the light from the star, as seen by Kepler’s telescope, the intensity of the light coming from that star decreases just a little bit, and scientists conclude the temporary decrease in illumination may have been caused by the transit of a planet in front of the star. If the telescope is then able to see a planet orbiting the star, like telescopes on Earth can see Jupiter, NASA calls the discovery “confirmed.”
And unlike the reaction wheel, the telescope appears to be fine. So far, Kepler has detected several planets and has identified other stars that planets might be orbiting:
- Number of stars to be analyzed: about 150,000
- Constellations where those stars are located: Cygnus, Lyra
- Confirmed planets detected so far: 130
- Planet “candidates” detected but not yet confirmed: 2,740
- Planets or candidates that have a size like Earth: 230
- Planets or candidates that are only about twice as big as Earth: 820
Celestial bodies in the last two categories are probably rocky worlds like Earth. But if Kepler’s mission stops at this point, NASA’s scientists may have to figure out another use for the orbiting telescope.