Kepler Spacecraft Finds More Earthlike Planets

Kepler Spacecraft

The Kepler Spacecraft finds more Earth-like planets, significantly increasing number of suspects in the search for extraterrestrial life, according to a NASA press release. Launched on March 7, 2009 on a mission to find new planets among the stars, the spacecraft was named for Johannes Kepler, the 17th century astronomer best known for identifying the laws of planetary motion. In the fifth year of its mission, the Kepler spaceship has now identified a treasure trove of 715 planets circling 305 stars, which indicates that some of those planets are in multi-planet systems.

The good news is that four of the newly identified planets occupy the “Goldilocks Zone,” the human habitable region around a star where it is warm enough for liquid water to be present, but not too warm for terrestrial life to exist there. The four planets in the Goldilocks Zone are also less than 2.5 times the size of the Earth, which means that the gravity on those planets will be near Earth normal levels.

The bad news is that the planets are hundreds of light years away from us, which means that it would take hundreds of years traveling at the speed of light to get there, putting them out of range for deep space exploration.

On the basis of the information collected by the Kepler mission, it appears that one out of every five stars with characteristics similar to the Earth’s sun will have earth-sized planets revolving around them.

What the Kepler spacecraft has also found is evidence that the spaceship’s namesake, Johannes Kepler, was right when he predicted that planets would revolve around other suns in approximately the same order of precedence that the revolve around the Earth’s sun. Kepler’s observations about planetary movements are important because they were one of the foundations of Isaac Newton’s theories of gravity.

The Kepler spaceship has no telescopes on board. The only scientific research instrument on the ship is a photometer that monitors the brightness of more than 145,000 stars in a fixed quadrant of space. The photometer, which is similar to an electric eye identifies periodic patterns of dimming light from the stars under scrutiny, which indicates that a planet is passing between the star and the observation point provided by the Kepler spacecraft.

The data transmitted from the Kepler spaceship is collated and analyzed to identify the patterns of light received from the stars, from which scientists are able to determine the size, speed and orbits of the planets that Kepler has discovered.

On the basis of the Kepler Spacecraft data, combined with previous reports from Kepler and other sources, we now know that there are at least 106 Earth-sized planets among the 800-odd plants that have been found. That eight-to-one ratio is very interesting because, the Earth’s solar system has precisely same eight-to-one ratio of earth sized planets.

The Kepler Spacecraft is part of NASA’s Discovery Program of relatively low-cost primary science missions, and has a $600 million price tag. Several reaction wheels – part of the gyroscopic aiming system, failed early on, so the Kepler mission control team is getting these results using the two remaining reaction wheels and the spacecraft’s thrusters to orient the Kepler toward its targets.

The spacecraft captures the images of the planets transiting across their stars with an array of photosensitive CCDs that, together, generate more data than the system can transmit, so NASA may be leaving some crumbs on the table for future missions.  Unfortunately, Kepler will not be able to provide pictures of the new members of the family of planets.  Kepler is not equipped with a telescope and the planets in question are too far away for photography.

Generations of science fiction readers marveled at the stories written by Arthur C. Clarke, Robert Heinlein and Isaac Asimov about far distant futures and great space voyages but, while they were writing their stories, the authors themselves did not know if, indeed, there were any planets anywhere else in the universe.

All three men believed that there were other planets circling other stars and that human beings would someday visit them. Asimov said it best, at a lecture at MIT shortly before his death. “The universe simply would not make sense to me if we were the only beings in it.”  Now that the Kepler Spacecraft has shown us just how crowded our neighborhood is,  we know what Asimov could only suspect: space is filling up as more planets are found.

By Alan Milner


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