It may come as no surprise to those who know NASA's penchant for coming up with amazingly cool solutions to major problems, but its still pretty intersting when you some major innovation pulled off.
This maybe the case with NASA's planet-hunting space telescope Kepler, which has been out of commission since May and thought to be kaput.
But this week the space agency said it has come up with a way to make use of the Sun and Kepler's orbit around it to stabilize the craft and let it start taking images of space again.
The story goes that in May, Kepler lost the second of four gyroscope-like reaction wheels, which are used to precisely point the spacecraft for extended periods of time, ending new data collection for the original mission. The spacecraft required three working wheels to maintain the precision pointing necessary to detect the signal of small Earth-sized exoplanets, which are planets outside our solar system, orbiting stars like our sun in what's known as the habitable zone -- the range of distances from a star where the surface temperature of a planet might be suitable for liquid water, NASA stated.
With the failure of a second reaction wheel, the spacecraft could no longer precisely point at the mission's original field of view where it would look for these exoplanets.
NASA Kepler and Ball Aerospace engineers say they have developed a way of recovering this pointing stability by maneuvering the spacecraft so that solar pressure - the pressure exerted when the photons of sunlight strike the spacecraft -- is evenly distributed across the surfaces of the spacecraft.
NASA says by orienting the spacecraft nearly parallel to its orbital path around the sun, which is slightly offset from the ecliptic, the orbital plane of Earth, it can achieve spacecraft stability. The ecliptic plane defines the band of sky in which lie the constellations of the zodiac.
This technique of using the sun as the 'third wheel' to control pointing is currently being tested on the spacecraft and early results look good, NASA said. During a pointing performance test in late October, a full frame image of the space telescope's full field of view was captured showing part of the Sagittarius constellation.
"Photons of light from a distant star field were collected over a 30-minute period and produced an image quality within five percent of the primary mission image quality, which used four reaction wheels to control pointing stability. Additional testing is underway to demonstrate the ability to maintain this level of pointing control for days and weeks," NASA said.
NASA says the Kepler "Second Light" concept has been presented to NASA Headquarters and a decision on whether or not to proceed with it could come by the end of December.
So why is Kepler so important? Some of the newer stats on Kepler findings include:
- From the first three years of Kepler data, it has spotted 3,583 planet candidates. Recently released analysis led by Jason Rowe, research scientist at the SETI Institute in Mountain View, Calif., determined that the largest increase of 78 % was found in the category of Earth-sized planets. Rowe's findings support the observed trend that smaller planets are more common.
- A research team led by Erik Petigura, doctoral candidate at University of California, Berkeley using statistical analysis of nearly all four years of Kepler data suggests that one in five stars like the sun is home to a planet up to twice the size of Earth, orbiting in a temperate environment.
- Kepler's mission is to determine what percentage of stars like the sun harbor small planets the approximate size and temperature of Earth. For four years, the space telescope simultaneously and continuously monitors the brightness of more than 150,000 stars, recording a measurement every 30 minutes. More than a year of the collected data remains to be fully reviewed and analyzed.
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