As Carl Sagan memorably reminds us, we're not leaving Earth anytime soon. But as Carl Sagan also memorably reminds us, that's no reason not to keep learning about how we could leave Earth for other worlds someday.
That's what NASA's Kepler Mission is about: identifying other planets in distant solar systems -- some of which might be Earthlike. Kepler has already identified 1,235 candidate systems using an orbiting telescope, and this infographic shows all of them to scale with our own pale blue dot.
Actually, in this graphic, our native star is the pale dot, Jupiter is the black speck on its face, and Earth is a microscopic pinpoint (so small you can't even see it here without zooming way in) -- that circle off in the upper right corner, separated from the rest, is the Sun drawn to scale with the other stars in the Kepler collection. Each of them has at least one planet orbiting it, depicted as a small black shadow against the disc of its parent star. That's actually how NASA finds these planets in the first place -- by observing what are called "transits," when the light of the star is briefly and infinitesimally dimmed by an orbiting planet passing in front of it. (There are myriad other, more complicated ways of detecting exoplanets, but this is the most easily intuitable one.)
NASA's infographic looks simpler than it is. Besides showing over a thousand planets and stars to scale in one easily understandable image (no mean feat in itself), we also learn about Kepler's process -- the "transit" concept. The scale illustrations and color-coding also impart valuable information in aggregate: With one glance, we learn that the average solar system seen by Kepler has a pale, yellowish star roughly the size of our own, with at least one giant planet roughly the size of Jupiter.
"No duh," you might think -- didn't the Copernican principle already predict that? Yeah well, predictions are one thing but hard data is something else: The fact that many of these "just like us" solar systems exist at all, much less line up with what appear to be habitable conditions on an orbiting planet, was (and still is) hotly contested. But looking at this image, it's hard to deny: there really may be "other Earths" out there.
But how can we be sure? That's Kepler's real mission: to refine these twelve hundred candidate worlds down to a handful of sure things. Of these twelve hundred worlds, 54 were initially announced by NASA to be in the habitable zone -- that is, in the "Goldilocks" sweet spot that can support Earth-like life. (Some of them may have since been ruled out by other observations, but that's the ballpark.) Spectrometers can tell us amazingly detailed things about the conditions on a planet light-years away, and Kepler may just prove that there's a place out there for us, if -- as Carl Sagan memorably said -- we can get there without destroying ourselves here first.
COMMENTARY: NASA'S Kepler Mission has one singular purpose, to scan the interplanetary skies for habitable earth-sized planets that could support life.
The Kepler spacecraft lifted off March 6, 2009 aboard a Delta II rocket from Cape Canaveral Air Force Station in Florida. Launch occurred at 10:49 p.m. EST.
NASA’s Kepler Mission was named in honor of Johannes Kepler because he was the first person to describe the motions of planets about the Sun in such a way that their positions could be precisely predicted. He derived three laws of planetary motion from observational data taken by Tycho Brahe making him the first astrophysicist. Kepler’s first two laws of planetary motion were published in 1609, 400 years prior to launch. Ten years later, he published his third law of planetary motion, which describes how the orbital period (year) of a planet is proportional to the semimajor axis (distance) from the Sun.
The total cost of the Kepler Mission over its lifecycle is approximately $600 million. This includes the design, construction, launch and operation of the spacecraft as well as the scientific analysis of the data. The Kepler Mission team involves scientists and engineers, across the United States, Canada and Europe. Kepler is managed by JPL; the science office is at NASA Ames Research Center.
The Kepler Mission is scheduled to observe for a minimum of 3.5 years. The spacecraft is designed to observe up to 6 years. Generally, NASA’s Science Mission Directorate reviews active missions, and makes the decision to extend missions based upon the opportunity for further scientific discoveries. For more information, read “Launch Vehicle and Orbit.”
Kepler is in a heliocentric (Sun-centered) orbit. Kepler’s orbit was chosen to enable continuous observation of the target stars. This requires that the field of view of Kepler never be blocked. For a spacecraft in low-Earth orbit, nearly half of the sky is blocked by the Earth and the obscured region is constantly changing. The most energy efficient orbit beyond Earth orbit is a heliocentric (Sun centered) Earth-trailing orbit. An Earth-trailing heliocentric orbit with a period of 371 days provides the optimum approach to maintaining a stable trajectory that keeps the spacecraft within telecommunications capability.
Another advantage of this orbit is that it has a very-low disturbing torque on the spacecraft, which leads to a very stable pointing attitude. Not being in Earth orbit means that there are no torques due to gravity gradients, magnetic moments or atmospheric drag. The largest external torque then is that caused by light from the sun. This orbit also avoids the high-radiation dosage associated with an Earth orbit, but is subject to energetic particles from cosmic rays and solar flares. For more information, read “ Launch Vehicle and Orbit”
The Kepler spacecraft s about 2.7 meters (nine feet) in diameter and 4.7 meters (15.3 feet) high. The total mass at launch was 1052.4 kilograms (2,320.1 pounds) consisting of 562.7-kilograms (1240.5-pounds) for the spacecraft, 478.0-kilograms (1043.9-pounds) for the photometer, and 11.7 kilograms (25.8 pounds) of hydrazine propellant.
The sole instrument aboard Kepler is a photometer (or light meter), an instrument that measures the brightness variations of stars. The photometer consists of the telescope, the focal plane array, and the local detector electronics. Kepler is a 0.95-meter (37-inch) aperture Schmidt-type telescope with a 1.4-meter (55-inch) primary mirror. For an astronomical telescope, Kepler’s photometer has a very wide field of view: it’s about 15 degrees across. It would take 30 Moons lined up in a row to span the Kepler field of view. The photometer features a focal plane array with 95 million pixels. The focal plane array is the largest camera NASA has ever flown in space. For further information, read “Photometer and Spacecraft”
The photometer is composed of just one "instrument," which is, an array of 42 CCDs (charge coupled devices). Each 50x25 mm CCD has 2200x1024 pixels. The CCDs are read out every three seconds to prevent saturation. Only the information from the CCD pixels where there are stars brighter than mv=14 is recorded. (The CCDs are not used to take pictures. The images are intentionally defocused to 10 arc seconds to improve the photometric precision.) The data are integrated for 30 minutes.
Kepler will look at just one large area of the sky in the constellations Cygnus and Lyra. The star field for the Kepler Mission was selected based on the following constraints:
- The field must be continuously viewable throughout the mission.
- The field needs to be rich in stars similar to our sun because Kepler needs to observe more than 100,000 stars simultaneously.
- The spacecraft and photometer, with its sunshade, must fit inside a standard Delta II launch vehicle. The size of the optics and the space available for the sunshield require the center of the star field to be more than 55-degrees above or below the path of the sun as the spacecraft orbits the sun each year trailing behind the Earth. The Sun, Earth and Moon make it impossible to view some portions of the sky during an orbital year. Thus, Kepler looks above the ecliptic plane to avoid all these bright celestial objects.
Power is provided by four non-coplanar panels with a total area of 10.2 square meters (109.8 square feet) of solar collecting surface area. Combined, the 2860 individual solar cells can produce over 1,100 Watts. Power storage is provided by a 20 Amp-hour rechargeable lithium-ion battery.
The photometer is composed of just one "instrument," which is, an array of 42 CCDs (charge coupled devices). Each 50x25 mm CCD has 2200x1024 pixels. The CCDs are read out every three seconds to prevent saturation. Only the information from the CCD pixels where there are stars brighter than mv=14 is recorded. (The CCDs are not used to take pictures. The images are intentionally defocused to 10 arc seconds to improve the photometric precision.) The data are integrated for 30 minutes.
On January 10, 2011, NASA released a press release confirming the discovery of the first Earth-sized rocky planet.
Trent J. Perrotto
Headquarters, Washington Jan. 10, 2011
202-358-0321
[email protected]
Rachel Hoover
Ames Research Center, Moffett Field, Calif.
650-604-0643
[email protected]
RELEASE: 11-007
NASA'S KEPLER MISSION DISCOVERS ITS FIRST ROCKY PLANET
NASA's Kepler mission confirmed the discovery of its first rocky planet, named Kepler-10b. Measuring 1.4 times the size of Earth, it is the smallest planet ever discovered outside our solar system.
The discovery of this so-called exoplanet is based on more than eight months of data collected by the spacecraft from May 2009 to early January 2010.
"All of Kepler's best capabilities have converged to yield the first solid evidence of a rocky planet orbiting a star other than our sun," said Natalie Batalha, Kepler's deputy science team lead at NASA's Ames Research Center in Moffett Field, Calif., and primary author of a paper on the discovery accepted by the Astrophysical Journal. "The Kepler team made a commitment in 2010 about finding the telltale signatures of small planets in the data, and it's beginning to pay off."
Kepler's ultra-precise photometer measures the tiny decrease in a star's brightness that occurs when a planet crosses in front of it. The size of the planet can be derived from these periodic dips in brightness. The distance between the planet and the star is calculated by measuring the time between successive dips as the planet orbits the star.
Kepler is the first NASA mission capable of finding Earth-size planets in or near the habitable zone, the region in a planetary system where liquid water can exist on the planet's surface. However, since it orbits once every 0.84 days, Kepler-10b is more than 20 times closer to its star than Mercury is to our sun and not in the habitable zone.
Kepler-10 was the first star identified that could potentially harbor a small transiting planet, placing it at the top of the list for ground-based observations with the W.M. Keck Observatory 10-meter telescope in Hawaii.
Scientists waiting for a signal to confirm Kepler-10b as a planet were not disappointed. Keck was able to measure tiny changes in the star's spectrum, called Doppler shifts, caused by the telltale tug exerted by the orbiting planet on the star.
"The discovery of Kepler 10-b is a significant milestone in the search for planets similar to our own," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Although this planet is not in the habitable zone, the exciting find showcases the kinds of discoveries made possible by the mission and the promise of many more to come," he said.
Knowledge of the planet is only as good as the knowledge of the star it orbits. Because Kepler-10 is one of the brighter stars being targeted by Kepler, scientists were able to detect high frequency variations in the star's brightness generated by stellar oscillations, or starquakes. This analysis allowed scientists to pin down Kepler-10b's properties.
There is a clear signal in the data arising from light waves that travel within the interior of the star. Kepler Asteroseismic Science Consortium scientists use the information to better understand the star, just as earthquakes are used to learn about Earth's interior structure. As a result of this analysis, Kepler-10 is one of the most well characterized planet-hosting stars in the universe.
That's good news for the team studying Kepler-10b. Accurate stellar properties yield accurate planet properties. In the case of Kepler-10b, the picture that emerges is of a rocky planet with a mass 4.6 times that of Earth and with an average density of 8.8 grams per cubic centimeter -- similar to that of an iron dumbbell.
Ames manages 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 and 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 the Kepler science data.
Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters. For more information about the Kepler mission, visit:
It is absolutely incredible the number of astrophysical discoveries we have made. It's a pity that these planets, which we cannot really see, but can sense their presence through the gravitational effect they have on closeby stars, are so far away. Carl Sagan is probably smiling down on us knowing that we have finally succeeded in discovering Earth-sized planets that could actually support intelligent life. If intelligent alien life exists on some of those planets, perhaps they are doing the same thing, and have discovered us as well.
Courtesy of an article dated May 17, 2011 appearing in Fast Company Design and NASA Ames Rsearch Center
I hope they have som radio telescopes to home in on any earth like planet for signs of radio signals
Posted by: Neale | 05/22/2011 at 02:21 PM