Space telescope that found new worlds probably lost

The Kepler space telescope's honeycombed main mirror wieghs 86 percent less than solid designs. /NASA photo

After extending its 3.5-year mission by about six months, NASA's revolutionary Kepler space telescope is crippled and probably only has months to live.

Kepler has collected data leading to the stunning conclusion that there are potentially billions of Earth-like planets in our Milky Way galaxy. Kepler has discovered 132 planets that Earth-based telescopes have confirmed. There are 2,700 other Kepler planet discoveries awaiting confirmation.

The Goldilocks Principal underlies Kepler's mission: finding planets that are not only Earth-sized but also orbiting a Sun-like star in a "habitable zone." This orbital sweet spot is not too warm and not too cold; it's just right to support life.

With two of its four gyroscopes now inoperative, Kepler has enough fuel onboard to steady itself for about six months. The second "reaction wheel" broke last week, and Kepler's wobble is posing a daunting challenge to NASA engineers.

In a May 15 prepared statement, NASA reported: "With the failure of a second reaction wheel, it's unlikely the spacecraft will be able to return to the high pointing accuracy that enables its high precision (photo imaging)."

The following images are artists' conceptions of planets Kepler has observed:

Kepler-47 is a circumbinary solar system in the constellation Cygnus, one of the space telescope's primary study areas. Multiple planets orbit two stars in Kepler-47. /NASA image

Kepler-62f is the smallest Earth-like planet discovered in a solar system's habitable zone. /NASA image

Kepler-69c is a super-Earth-sized planet in the Cygnus constellation. /NASA image

KOI-961 is a compact Cygnus solar system similar in size to Jupiter and its moons. The KOI-961 planets orbit a red dwarf star. /NASA image

Kepler-35b is a Saturn-sized planet orbiting two stars. /NASA image

Kepler-22b is the first Earth-like planet found orbiting in its solar system's habitable zone. /NASA image

Kepler-11 has a Sun-like star and six planets. /NASA image