Starship Asterisk*

orin stepanek wrote:As per Doum! http://asterisk.apod.com/viewtopic.php?f=31&t=33004

I'd give new Kepler mission a 150 per cent chance'
NASA astrophysicist Steve Howell is confident that a new method of aiming the crippled Kepler space telescope will convince the space agency to keep it alive.

• Science 344(6181) 277 (18 Apr 2014) DOI: 10.1126/science.1249403
  arXiv.org > astro-ph > arXiv:1404.5667 > 22 Apr 2014

Sun’s stroke keeps Kepler online
Space telescope beats mechanical failures to begin a second mission that will trace new celestial targets.

Mark Zastrow
21 October 2014

The crippled Kepler space telescope is unexpectedly enjoying a second lease of life. The exoplanet-hunting probe will now cast its gaze on star clusters, the centre of the Milky Way and the Solar System’s outer planets as it scans a ribbon of the cosmos for the next three years. This month it has been gazing at gas clouds shrouding infant stars in the constellations Scorpius and Ophiuchus.

Click to view full size image

The telescope, originally designed to look for Earth-like planets orbiting other stars in our region of the Galaxy, has just yielded the first data set since its reincarnation after mechanical failures. Its science team is still busy analysing data from the initial planet-hunting mission, so Kepler’s managers at NASA have left it to the wider astronomical community to choose specific targets for a second mission, known as K2, and to comb through the output.

...[They] fashioned a crutch for Kepler using the only resource available: sunlight. Positioned so that its long side faces the Sun, the spacecraft leans against the pressure created by the onslaught of photons and balances using its two good wheels.
Read more here: http://www.nature.com/news/sun-s-stroke ... 023#kepler

[c]This artist's conception portrays the first planet discovered by the Kepler spacecraft
during its K2 mission. A transit of the planet was teased out of K2's noisier data using
ingenious computer algorithms developed by a CfA researcher. The newfound planet,
HIP 116454b, has a diameter of 20,000 miles (two and a half times the size of Earth)
and weighs 12 times as much. It orbits its star once every 9.1 days.
Credit: David A. Aguilar (CfA)[/c]

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To paraphrase Mark Twain, the report of the Kepler spacecraft's death was greatly exaggerated. Despite a malfunction that ended its primary mission in May 2013, Kepler is still alive and working. The evidence comes from the discovery of a new super-Earth using data collected during Kepler's "second life."

"Like a phoenix rising from the ashes, Kepler has been reborn and is continuing to make discoveries. Even better, the planet it found is ripe for follow-up studies," says lead author Andrew Vanderburg of the Harvard-Smithsonian Center for Astrophysics (CfA).

NASA's Kepler spacecraft detects planets by looking for transits, when a star dims slightly as a planet crosses in front of it. The smaller the planet, the weaker the dimming, so brightness measurements must be exquisitely precise. To enable that precision, the spacecraft must maintain a steady pointing.

Kepler's primary mission came to an end when the second of four reaction wheels used to stabilize the spacecraft failed. Without at least three functioning reaction wheels, Kepler couldn't be pointed accurately.

Rather than giving up on the plucky spacecraft, a team of scientists and engineers developed an ingenious strategy to use pressure from sunlight as a virtual reaction wheel to help control the spacecraft. The resulting second mission, K2, promises to not only continue Kepler's search for other worlds, but also introduce new opportunities to observe star clusters, active galaxies, and supernovae.

Due to Kepler's reduced pointing capabilities, extracting useful data requires sophisticated computer analysis. Vanderburg and his colleagues developed specialized software to correct for spacecraft movements, achieving about half the photometric precision of the original Kepler mission. ...

Astronomers announced today that they have found eight new planets in the "Goldilocks" zone of their stars, orbiting at a distance where liquid water can exist on the planet's surface. This doubles the number of small planets (less than twice the diameter of Earth) believed to be in the habitable zone of their parent stars. Among these eight, the team identified two that are the most similar to Earth of any known exoplanets to date. ...

• arXiv.org > astro-ph > arXiv:1501.01101 > 06 Jan 2015

[i]After the Kepler Space Telescope lost two if its four reaction wheels, it was unable to point accurately enough for long observations. A retooled mission, dubbed K2, is still able to obtain images of transiting planets by looking along the plane of the galaxy, or the ecliptic.[b](Credit: NASA)[/b][/i]

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NASA’s Kepler Space Telescope, despite being hobbled by the loss of critical guidance systems, has discovered a star with three planets only slightly larger than Earth. The outermost planet orbits in the “Goldilocks” zone, a region where surface temperatures could be moderate enough for liquid water and perhaps life to exist.

The star, EPIC 201367065, is a cool red M-dwarf about half the size and mass of our own sun. At a distance of 150 light years, the star ranks among the top 10 nearest stars known to have transiting planets. The star’s proximity means it’s bright enough for astronomers to study the planets’ atmospheres to determine whether they are like Earth’s atmosphere and possibly conducive to life. ...

The three planets are 2.1, 1.7 and 1.5 times the size of Earth. The outermost planet, at 1.5 Earth radii, is the smallest of the bunch and orbits far enough from its host star that it receives levels of light from its star similar to those received by Earth from the sun, said UC Berkeley graduate student Erik Petigura, who discovered the planets Jan. 6 while conducting a computer analysis of the Kepler data NASA has made available to astronomers. He calculated that the three planets receive 10.5, 3.2, and 1.4 times the light intensity of Earth. ...

• arXiv.org > astro-ph > arXiv:1501.03798 > 15 Jan 2015

[i]Kepler-444 is a recently discovered star with at least five Earth-size planets. The system is 11.2 billion years old. [b](Credit: Tiago Campante/Peter Devine)[/b][/i]

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Astronomers poring over four years of data from NASA’s Kepler spacecraft have discovered a star that’s 11.2 billion years old and has at least five Earth-size planets.

“We thus show that Earth-size planets have formed throughout most of the Universe’s 13.8-billion-year history, leaving open the possibility for the existence of ancient life in the Galaxy,” the astronomers wrote ...

The paper describes Kepler-444, a star that’s 25 percent smaller than our sun and is 117 light years from Earth. The star’s five known planets have sizes that fall between Mercury and Venus. Those planets are so close to their star that they complete their orbits in fewer than 10 days. At that distance, they’re all much hotter than Mercury and aren’t habitable. ...

Kepler-444 came from the first generation of stars. This system tells us that planets were forming around stars nearly 7 billion years before our own solar system. ...

• arXiv.org > astro-ph > arXiv:1501.06227 > 26 Jan 2015

Where is everybody?