NASA's Kepler dazzles with first pics in new-Earth hunt
One snapshot, millions of stars
NASA's Kepler space telescope has sent home the first images of the starry patch of sky where it will soon begin the hunt for Earth-like planets.
The first snaps show Kepler's entire field of view, a 100-square-degree portion of the sky in the Cygnus-Lyra region of the Milky Way, roughly equivalent to the size of two side-by-side dips of the Big Dipper.
The mission will spend the next three-and-a-half years scouring the area looking for minute fluctuations in the stars' brightness as their orbiting planets cross Kepler's field of view.
Scientists hope to find evidence of extra-solar worlds the size of Earth in habitable zones around stars like the Sun - planets that could be a suitable home for life as we know it.
"Kepler's first glimpse of the sky is awe-inspiring," said Lia LaPiana, Kepler's program executive at NASA DC headquarters. "To be able to see millions of stars in a single snapshot is simply breathtaking."
You're out there somewhere: 14 million stars in the full field of view
This first shot shows Kepler's full field of view, containing an estimated 14 million stars. More than 100,000 of these have been selected as candidates for the agency's planet hunting, NASA said.
The image has been color-coded to show brighter stars in white and fainter stars in red. It's a 60-second exposure taken on April 8, just one day after the spacecraft jettisoned its dust cover.
Lyra, Lyra, stars on fire-ra
This image zooms in on 0.2 per cent of Kepler's full field of view, showing hundreds of stars in the constellation Lyra.
@John Smith 23 April 12:48
Sorry for being off line have been tied up in teaching!
Yes within in individual system, the planets ought to be reasonable
coplanar, if they've formed out of an accretion disc as we expect (and
conservation of momentum is a strong prior!). But that only means
within a few degrees, once they've had a bit of post-formation
battering - I think back-of-an-envelope for example, if Kepler found
Earth, it would have a about a 50/50 chance of getting one transit of
Mars; Mercury and Venus would be out through inclination, Jupiter and
further would be out through mission length.
But between stars - the ecliptics will be pretty much at random. So
Kepler would still need 200 solar systems to detect one Earth.
I hadn't head about the Daedalus revisit - will keep my eyes open for
that, it's still the horse I'd put my money on. Starwisp though -
unsteerable mirror that has to be also a Fresnel lens from Earth?
Free-flying optical arrays in ~AU orbit would have much greater senstivity
& mapping power - local angular resolution at a wavelength where the
targets are dim and with an unsteerable antenna isn't FTW! Seriously - blackbody in the Rayleigh-Jeans regime goes as nu^2. Push me offline and I'll calculate precisely how close you'd need to be to Earth with an off-axis 30-m cm-wave antenna to detect it. There's several orders of magnitude on the back of my bus ticket in favor of going for a local optical/IR search!
I had not realised the odds of the orbit being favourable were so long. It was my impression most planetary orbits were in a plane around their suns and most of these planes were themselves more or less parallel to each other. It helps to put some actual bounds on the size of this problem
“more realistic I think would be a Deadalus-type 0.1c ship”
The BIS are re-visiting the design to see what changes have occurred in 30 years. The substantial improvements in sensor technology should shrink the required payload quite a lot and the improvements in fusion understanding should increase efficiency. However mining Jupiter for the fuel will remain a big problem. Sadly the evidence for a suspected planetary system around Barnards Star seems to have been discredited
Outside Orion and Daedelus the only other idea would be the Starwisp idea of Robert Forward. Improvements in sensor processing have made the concept of a lens less large area sensor more viable. It also keeps most of the key bits in Earth orbit.
@ John Smith
Well, the chance of detecting the Earth by occultation against the Sun from a random line-of-sight is about 0.5%. (You'd be looking for a 0.001% dip in brightness that lasted a few hours once a year). So, given that there are only 11 stars with 10 light years of the Sun, it's not a huge surprise that we haven't detected any Earth-like planets yet - they may well be there, but with their orbits too far from edge-on. But my understanding is it won't be more that a few years before we start getting detections or good upper limits from direct imaging/interferometry.
Interestingly just yesterday the HARPS team (radial velocity) announced they had found a 2 Earth-mass planet - but in a 3-day orbit. They've been studying that particular system for a long time a have been beating down the signal/noise ratio, but the technique still fundamentally needs the planet to be throwing the star around at a fair speed.
As is often lamented we *could* build an Orion-type 0.05c ship now... more realistic I think would be a Deadalus-type 0.1c ship, in ~100 years maybe. As you say, knowing there was a terrestrial planet at the target star would be a huge motivation (that was indeed the basis for the Daedalus mission profile to Barnard's Star if I remember correctly) but I wonder if even on 100-year time scales we'd be rich and motivated enough to do it...