MOFFET FIELD, Calif. — NASA’s Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet’s surface, but they are the smallest exoplanets ever confirmed around a star like our sun.

The discovery marks the next important milestone in the ultimate search for planets like Earth. The new planets are thought to be rocky. Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of Earth. Kepler-20f is a bit larger than Earth, measuring 1.03 times its radius. Both planets reside in a five-planet system called Kepler-20, approximately 1,000 light-years away in the constellation Lyra.

Kepler-20e orbits its parent star every 6.1 days and Kepler-20f every 19.6 days. These short orbital periods mean very hot, inhospitable worlds. Kepler-20f, at 800 degrees Fahrenheit, is similar to an average day on the planet Mercury. The surface temperature of Kepler-20e, at more than 1,400 degrees Fahrenheit, would melt glass.

“The primary goal of the Kepler mission is to find Earth-sized planets in the habitable zone,” said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., lead author of a new study published in the journal Nature. “This discovery demonstrates for the first time that Earth-size planets exist around other stars, and that we are able to detect them.”

The Kepler-20 system includes three other planets that are larger than Earth but smaller than Neptune. Kepler-20b, the closest planet, Kepler-20c, the third planet, and Kepler-20d, the fifth planet, orbit their star every 3.7, 10.9 and 77.6 days. All five planets have orbits lying roughly within Mercury’s orbit in our solar system. The host star belongs to the same G-type class as our sun, although it is slightly smaller and cooler.

The system has an unexpected arrangement. In our solar system, small, rocky worlds orbit close to the sun and large, gaseous worlds orbit farther out. In comparison, the planets of Kepler-20 are organized in alternating size: large, small, large, small and large.

“The Kepler data are showing us some planetary systems have arrangements of planets very different from that seen in our solar system,” said Jack Lissauer, planetary scientist and Kepler science team member at NASA’s Ames Research Center in Moffett Field, Calif. “The analysis of Kepler data continue to reveal new insights about the diversity of planets and planetary systems within our galaxy.”

Scientists are not certain how the system evolved but they do not think the planets formed in their existing locations. They theorize the planets formed farther from their star and then migrated inward, likely through interactions with the disk of material from which they originated. This allowed the worlds to maintain their regular spacing despite alternating sizes.

The Kepler space telescope detects planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets crossing in front, or transiting, their stars. The Kepler science team requires at least three transits to verify a signal as a planet.

The Kepler science team uses ground-based telescopes and the Spitzer Space Telescope to review observations on planet candidates the spacecraft finds. The star field Kepler observes in the constellations Cygnus and Lyra can be seen only from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets.

To validate Kepler-20e and Kepler-20f, astronomers used a computer program called Blender, which runs simulations to help rule out other astrophysical phenomena masquerading as a planet.

On Dec. 5 the team announced the discovery of Kepler-22b in the habitable zone of its parent star. It is likely to be too large to have a rocky surface. While Kepler-20e and Kepler-20f are Earth-size, they are too close to their parent star to have liquid water on the surface.

“In the cosmic game of hide and seek, finding planets with just the right size and just the right temperature seems only a matter of time,” said Natalie Batalha, Kepler deputy science team lead and professor of astronomy and physics at San Jose State University. “We are on the edge of our seats knowing that Kepler’s most anticipated discoveries are still to come.”

NASA’s Ames Research Center in Moffett Field, Calif., manages Kepler’s ground system development, mission operations and science data analysis. JPL managed the Kepler mission’s 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 Kepler science data. Kepler is NASA’s 10th Discovery Mission and is funded by NASA’s Science Mission Directorate at the agency’s headquarters in Washington.

For more information about the Kepler mission and to view the digital press kit, visit: http://www.nasa.gov/kepler

NOAO: New Planet Kepler-21b discovery a partnership of both space and ground-based observations

The NASA Kepler Mission is designed to survey a portion of our region of the Milky Way Galaxy to discover Earth-size planets in or near the “habitable zone,” the region in a planetary system where liquid water can exist, and determine how many of the billions of stars in our galaxy have such planets. It now has another planet to add to its growing list. A research team led by Steve Howell, NASA Ames Research Center, has shown that one of the brightest stars in the Kepler star field has a planet with a radius only 1.6 that of the earth’s radius and a mass no greater that 10 earth masses, circling its parent star with a 2.8 day period. With such a short period, and such a bright star, the team of over 65 astronomers (that included David Silva, Ken Mighell and Mark Everett of NOAO) needed multiple telescopes on the ground to support and confirm their Kepler observations. These included the 4 meter Mayall telescope and the WIYN telescope at Kitt Peak National Observatory. The accompanying figure shows the size of the Kepler field, seen over Kitt Peak.

With a period of only 2.8 days, this planet, designated Kepler-21b, is only about 6 million km away from its parent star. By comparison Mercury, the closest planet to the sun, has a period of 88 days and a distance from the sun almost ten times greater, or 57 million km. So Kepler 21b is far hotter than any place humans could venture. The team calculates that the temperature at the surface of the planet is about 1900 K, or 2960 F. While this temperature is nowhere near the habitable zone in which liquid water might be found, the planet’s size is approaching that of the earth.

The parent star, HD 179070, is quite similar to our sun: its mass is 1.3 solar masses, its radius is 1.9 solar radii, and its age, based on stellar models, is 2.84 billion years (or a bit younger than the sun’s 4.6 billion years). HD 179070 is spectral type F6 IV, a little hotter and brighter than the sun. By astronomical standards, HD 179070 is fairly close, at a distance from the sun of 352 light years. While it cannot be seen by the unaided eye, a small telescope can easily pick it out.

Part of the difficulty in detecting this planet is the realization, from the Kepler mission, that many stars show short period brightness oscillations. The effect of these must be removed from the stellar light in order to uncover the regular, but very small, dimming caused by the planet passing in front of the star. The Kepler mission observed this field for over 15 months, and the team combined the observations to enable them to detect this tiny, periodic signal. They also relied on spectroscopic and imaging data from a number of ground based telescopes. The attached figure 2 shows a light curve: a plot of the brightness of HD 179070 over time as the planet passes in front of it. This curve was built up over the many months of observing.

The results of this work have been accepted for publication in the Astrophysical Journal.

NOAO is operated by Association of Universities for Research in Astronomy Inc. (AURA) under a cooperative agreement with the National Science Foundation.

Less than a month after NASA’s falling UARS satellite grabbed the headlines, the German space agency says one of its abandoned satellites will dive back to Earth later this month, but no one knows where it will land.

The ROSAT X-ray astronomy observatory is smaller and less massive than NASA’s Upper Atmospheric Research Satellite, or UARS, which fell back to Earth on Sept. 24. But officials predict it will spread three times more debris and pose a greater threat to people than UARS.

That’s because ROSAT is made of heat-resistant components, especially its primary mirror, which officials say will probably be the largest single fragment that will reach Earth.

The satellite will streak into the atmosphere at 17,000 mph, and temperatures up to 3,000 degrees Fahrenheit will burn up much of the spacecraft.

“All these forces exerted on the satellite cause it to disintegrate, which in turn means that it eventually lands in the form of a long debris trail,” said Heiner Klinkrad, head of the European Space Agency’s space debris office. “The lightweight objects fall to Earth first, similar to leaves from a tree. The really heavy objects land later, because they ultimately have to drill their way through the atmosphere.”

But engineers expect the bulk of ROSAT to survive re-entry, littering its impact point with up to 30 pieces of debris.

The 5,348-pound satellite launched from Florida on a Delta 2 rocket in 1990. ROSAT does not have an engine or propulsion system because it used reaction wheels to point its telescope toward scientific targets in the cosmos.

Up to 3,750 pounds of the satellite could reach Earth’s surface. NASA said they expected 1,200 pounds of UARS to survive re-entry.

There is a 1-in-2,000 chance someone will be struck by fragments of ROSAT on its way down, according to Germany. That equates to odds of about 1-in-14 trillion that any individual person will be hit.

The threat from UARS wasn’t as high. An analysis from NASA showed there was a 1-in-3,200 chance of a collision between a human and a piece of UARS.

The remnants of UARS fell in the remote Pacific Ocean, and ROSAT will likely also end up in the sea, but its impossible to tell where it will crash until hours before.

ROSAT launched in June 1990 on a Delta 2 rocket.

ROSAT, which stands for Roentgen Satellite, was turned off in 1999, and its altitude has gradually dropped since then from an operational orbit more than 350 miles high. The German Aerospace Center, also known as DLR by its German acronym, says the spacecraft should re-enter the atmosphere between Oct. 20 and Oct. 25.

But the margin of error in the re-entry forecast is three days, and officials likely won’t know where the satellite will come down until after it falls. Even one day before re-entry, the time of ROSAT’s demise will only be known with a precision of plus-or-minus five hours, putting entire oceans and continents in the satellite’s flight path.

“All areas under the orbit of ROSAT, which extends to 53 degrees northern and southern latitude could be affected by its re-entry,” said a posting on DLR’s website. “The bulk of the debris will impact near the ground track of the satellite.”

“It will not be possible to make any kind of reliable forecast about where the satellite will actually come down until about one or two hours before the fact,” Klinkrad said. “It will, however, be possible to predict, about one day in advance, which geographical regions will definitely not be affected.”

ROSAT’s orbit was at an average altitude of 149 miles Wednesday.

“This slow descent is due to the friction encountered by the satellite as it enters the outer fringes of Earth atmosphere, which increases the more ROSAT penetrates into our atmosphere,” Klinkrad said.

Klinkrad said the major factor affecting a satellite’s fall from orbit is solar activity. Energy unleashed from the sun causes Earth’s atmosphere to heat up and expand, generating more drag for satellites in low orbits.

Fluctuations in solar activity can quicken or slow a satellite’s re-entry. Experts initially expected ROSAT’s plunge to occur last year, but solar activity turned out to be less than predicted, delaying the re-entry until this month.

Update #6
Tue, 20 Sep 2011 02:00:29 PM MDT
As of Sept. 20, 2011, the orbit of UARS was 127 mi by 140 mi (205 km by 225 km). Re-entry is expected Sept. 23, plus or minus a day. It is still too early to predict the time and location of re-entry. Predictions will become more refined over the next two days.

NASA will post updates weekly until four days before the anticipated re-entry, then daily until about 24 hours before re-entry, and then at about 12 hours, six hours and two hours before re-entry. The updates will come from the Joint Space Operations Center of U.S. Strategic Command at Vandenberg Air Force Base, Calif., which works around the clock detecting, identifying and tracking all man-made objects in Earth orbit, including space junk.
The actual date of re-entry is difficult to predict because it depends on solar flux and the spacecraft’s orientation as its orbit decays. As re-entry draws closer, predictions on the date will become more reliable.

The risk to public safety or property is extremely small, and safety is NASA’s top priority. Since the beginning of the Space Age in the late-1950s, there have been no confirmed reports of an injury resulting from re-entering space objects. Nor is there a record of significant property damage resulting from a satellite re-entry.

If you find something you think may be a piece of UARS, do not touch it. Contact a local law enforcement official for assistance.

Enjoy a tour of lunar landing sites as NASA’s GRAIL mission launches to the moon this month.

Unlike Star Wars’ Tatooine, Kepler-16b is cold, gaseous and not thought to harbor life, but its discovery demonstrates the diversity of planets in our galaxy. Previous research has hinted at the existence of circumbinary planets, but clear confirmation proved elusive. Kepler detected such a planet, known as Kepler-16b, by observing transits, where the brightness of a parent star dims from the planet crossing in front of it.

“This discovery confirms a new class of planetary systems that could harbor life,” Kepler principal investigator William Borucki said. “Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now.”

Embedded video from

NASA Jet Propulsion Laboratory California Institute of

A supernova discovered yesterday is closer to Earth — approximately 21 million light-years away — than any other of its kind in a generation. Astronomers believe they caught the supernova within hours of its explosion, a rare feat made possible with a specialized survey telescope and state-of-the-art computational tools

At a mere 21 million light-years from Earth, a relatively small distance by astronomical standards, the supernova is still getting brighter, and might even be visible with good binoculars in ten days’ time, appearing brighter than any other supernova of its type in the last 30 years.

What’s up for August? Planets with atmospheres! Venus has thick clouds, Mars has dust devils, and the outer planets have fierce winds. Why not have a look at Jupiter rising near midnight this month? The Juno Mission to Jupiter launches this month, too.

NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 9, 2011. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

PASADENA, Calif. — On July 15, NASA’s Dawn spacecraft will begin a prolonged encounter with the asteroid Vesta, making the mission the first to enter orbit around a main-belt asteroid.

The main asteroid belt lies between the orbits of Mars and Jupiter. Dawn will study Vesta for one year, and observations will help scientists understand the earliest chapter of our solar system’s history.

As the spacecraft approaches Vesta, surface details are coming into focus, as seen in a recent image taken from a distance of about 26,000 miles (41,000 kilometers). The image is available at:
Source -

Engineers expect the spacecraft to be captured into orbit at approximately 10 p.m. PDT Friday, July 15 (1 a.m. EDT Saturday, July 16). They expect to hear from the spacecraft and confirm that it performed as planned during a scheduled communications pass that starts at approximately 11:30 p.m. PDT on Saturday, July 16 (2:30 a.m. EDT Sunday, July 17). When Vesta captures Dawn into its orbit, engineers estimate there will be approximately 9,900 miles (16,000 kilometers) between them. At that point, the spacecraft and asteroid will be approximately 117 million miles (188 million kilometers) from Earth.

“It has taken nearly four years to get to this point,” said Robert Mase, Dawn project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Our latest tests and check-outs show that Dawn is right on target and performing normally.”

Engineers have been subtly shaping Dawn’s trajectory for years to match Vesta’s orbit around the sun. Unlike other missions, where dramatic propulsive burns put spacecraft into orbit around a planet, Dawn will ease up next to Vesta. Then the asteroid’s gravity will capture the spacecraft into orbit. However, until Dawn nears Vesta and makes accurate measurements, the asteroid’s mass and gravity will only be estimates. So the Dawn team will need a few days to refine the exact moment of orbit capture.

Launched in September 2007, Dawn will depart for its second destination, the dwarf planet Ceres, in July 2012. The spacecraft will be the first to orbit two solar system destinations beyond Earth.

Dawn’s mission to Vesta and Ceres is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are part of the mission team.

For a current image of Vesta and more information about the Dawn mission, visit: http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov .You also can follow the mission on Twitter at: http://www.twitter.com/nasa_dawn .

Priscilla Vega/Jia-Rui Cook 626-298-3290/818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
priscilla.r.vega@jpl.nasa.gov / jccook@jpl.nasa.gov

Dwayne C. Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

Don Yeomans & Paul Chodas
NASA/JPL Near-Earth Object Program Office
June 23, 2011
Updated: June 26, 2011

Trajectory of 2011 MD projected onto the Earth's orbital plane. Note from this viewing angle, the asteroid passes underneath the Earth.

Trajectory of 2011 MD from the general direction of the Sun.

Near-Earth asteroid 2011 MD will pass only 12,300 kilometers (7,600 miles) above the Earth’s surface on Monday June 27 at about 1:00 PM EDT. The asteroid was discovered by the LINEAR near-Earth object discovery team observing from Socorro, New Mexico. The diagram on the left shows the trajectory of 2011 MD projected onto the Earth’s orbital plane over a four-day interval. The diagram on the left gives another view from the general direction of the Sun that indicates that 2011 MD will reach its closest Earth approach point in extreme southern latitudes (in fact over the southern Atlantic Ocean). This small asteroid, only 5-20 meters in diameter, is in a very Earth-like orbit about the Sun, but an orbital analysis indicates there is no chance it will actually strike Earth on Monday. The incoming trajectory leg passes several thousand kilometers outside the geosynchronous ring of satellites and the outgoing leg passes well inside the ring. One would expect an object of this size to come this close to Earth about every 6 years on average. For a brief time, it will be bright enough to be seen even with a modest-sized telescope.