sábado, 3 de mayo de 2014
NASA : Kepler Mission Manager Update: Leadership Change
Kepler's Second Light: How K2 Will Work
In May, Kepler lost the second of four gyroscope-like reaction wheels, ending new data collection for the original mission. A new mission concept, dubbed K2, would continue Kepler's search for other worlds, and introduce new opportunities to observe star clusters, young and old stars, active galaxies and supernovae.
Using the sun and the two remaining reaction wheels, engineers have devised an innovative technique to stabilize and control the spacecraft in all three directions of motion. This technique of using the sun as the 'third wheel' to control pointing is currently being tested on the spacecraft.
To achieve the necessary stability, the orientation of the spacecraft must be nearly parallel to its orbital path around the sun, which is slightly offset from the ecliptic, the orbital plane of Earth. The ecliptic plane defines the band of sky in which lie the constellations of the zodiac.
K2 would study a specific portion of the sky for up to 83 days, until it is necessary to rotate the spacecraft to prevent sunlight from entering the telescope. Each orbit or year would consist of approximately 4.5 unique viewing periods or campaigns.
The K2 mission concept has been presented to NASA Headquarters. A decision to proceed to the 2014 Senior Review – a biannual assessment of operating missions – and propose for budget to fly K2 is expected by the end of 2013.
Image credit: NASA Ames/W Stenzel
Kepler Mission Manager Update: Leadership Change
May 2, 2014
Today the team announces a change in project management.
"This is my final input for the Kepler Mission Manager Update. It has been a great pleasure to be associated with the Kepler mission since May 2008. The Kepler team has accomplished so much and its contributions to exoplanet science and astronomy are historic and, in many cases, without precedence. Though begun as a Discovery class mission, Kepler is more than worthy of Great Observatory fame. Its discoveries will long be remembered in textbooks and the annals of history with many “firsts.” As Charlie Sobeck continues as the Kepler Project Manager, I congratulate him and the Kepler team on the mission’s remarkable successes. I’m certain their successes will continue with the proposed two-wheel “K2” mission, and it will continue to amaze with even more discoveries yet to come. As I assume other duties at NASA's Ames Research Center, I bid the team a fond farewell — GO KEPLER!"
Roger (aka Colonel R. P. Hunter)
While Roger moves on to other tasks, the work on Kepler continues.
We are currently in the midst of an end-to-end shakedown of the proposed K2 mission, performing our Campaign 0, observing in the ecliptic plane. While this is primarily an engineering test of the K2 mission, we are collecting science data on approximately 8,000 targets, including most of the open star cluster M35. Campaign 0 is being conducted in preparation for the K2 mission, if it is approved, following the 2014 Astrophysics Senior Review of Operating Missions.
During the first half of the campaign, we discovered a pointing instability that eventually took the spacecraft to safe mode. Before resuming the second half of the campaign, we took advantage of the break to investigate the cause of the instability and engineer a robust solution. With this complete, we are now back to data collection, and expect to continue Campaign 0 through May 28.
If the K2 mission is approved, the team will begin Campaign 1 operations in early June. Working to this assumption, we have actively engaged the scientific community to identify the precise pointing of the early campaigns and to solicit targets for observation. Our team has developed a new star catalog (the K2 Ecliptic Plane Input Catalog – EPIC) to assist observers in choosing targets. The community has responded with enthusiasm, and the target selection process for Campaign 1 is nearly complete.
This month also saw the announcement of Kepler-186f, the first Earth-size planet in the habitable zone of another star! This announcement marked yet another milestone step in the path that leads to answering the question: Are we alone?
With Roger’s departure, I am honored to have the opportunity to continue working this exciting mission with an outstanding group of people and partner organizations. We will all do our best to complete the work that has been entrusted to us.
NASA's Kepler Discovers First Earth-Size Planet In The 'Habitable Zone' of Another Star
April 17, 2014
Using NASA's Kepler Space Telescope, astronomers have discovered the first Earth-size planet orbiting a star in the "habitable zone" -- the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exist in the habitable zone of stars other than our sun.
While planets have previously been found in the habitable zone, they are all at least 40 percent larger in size than Earth and understanding their makeup is challenging. Kepler-186f is more reminiscent of Earth.
"The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth," said Paul Hertz, NASA's Astrophysics Division director at the agency's headquarters in Washington. "Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind's quest to find truly Earth-like worlds."
Although the size of Kepler-186f is known, its mass and composition are not. Previous research, however, suggests that a planet the size of Kepler-186f is likely to be rocky.
"We know of just one planet where life exists -- Earth. When we search for life outside our solar system we focus on finding planets with characteristics that mimic that of Earth," said Elisa Quintana, research scientist at the SETI Institute at NASA's Ames Research Center in Moffett Field, Calif., and lead author of the paper published today in the journal Science. "Finding a habitable zone planet comparable to Earth in size is a major step forward."
Kepler-186f resides in the Kepler-186 system, about 500 light-years from Earth in the constellation Cygnus. The system is also home to four companion planets, which orbit a star half the size and mass of our sun. The star is classified as an M dwarf, or red dwarf, a class of stars that makes up 70 percent of the stars in the Milky Way galaxy.
"M dwarfs are the most numerous stars," said Quintana. "The first signs of other life in the galaxy may well come from planets orbiting an M dwarf."
Kepler-186f orbits its star once every 130-days and receives one-third the energy from its star that Earth gets from the sun, placing it nearer the outer edge of the habitable zone. On the surface of Kepler-186f, the brightness of its star at high noon is only as bright as our sun appears to us about an hour before sunset.
"Being in the habitable zone does not mean we know this planet is habitable. The temperature on the planet is strongly dependent on what kind of atmosphere the planet has," said Thomas Barclay, research scientist at the Bay Area Environmental Research Institute at Ames, and co-author of the paper. "Kepler-186f can be thought of as an Earth-cousin rather than an Earth-twin. It has many properties that resemble Earth."
The four companion planets, Kepler-186b, Kepler-186c, Kepler-186d, and Kepler-186e, whiz around their sun every four, seven, 13, and 22 days, respectively, making them too hot for life as we know it. These four inner planets all measure less than 1.5 times the size of Earth.
The next steps in the search for distant life include looking for true Earth-twins -- Earth-size planets orbiting within the habitable zone of a sun-like star -- and measuring the their chemical compositions. The Kepler Space Telescope, which simultaneously and continuously measured the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-size planets around stars like our sun.
Ames is responsible for Kepler's ground system development, mission operations, and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and was funded by the agency's Science Mission Directorate.
The SETI Institute is a private, nonprofit organization dedicated to scientific research, education and public outreach. The mission of the SETI Institute is to explore, understand and explain the origin, nature and prevalence of life in the universe.
For more information about the Kepler mission, visit:
Guillermo Gonzalo Sánchez Achutegui