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tacitus
Posted on: Aug 1 2010, 05:43 AM


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I think it's all but inevitable that we will end up probing other planetary systems to the limit of the physically possible eventually, even if it's not within the next 25 years. Given the near impossibility of interstellar travel, the only means of exploring our galactic neighborhood that will be available to us for decades, and very likely for centuries, will be telescopic missions, be they in Earth's orbit, at L2, in the outer reaches of the solar system, beyond the zodiacal dust cloud, and even to the focal point of the Sun's gravitational lens at a distance of 550AU.

And yes, there will be fleets of interferometric telescopes one day, because unless we quickly reach the theoretical viewing limits, it will continue to be our only means of imaging and gathering more information about extrasolar planets.

So Google Galaxy is right. We're almost certainly going to have a catalog of millions of planets one day, even if we can only take images sharp enough to create maps of the surface features of the nearest few thousand or so.

Good times...
  Forum: Telescopic Observations · Post Preview: #162830 · Replies: 1264 · Views: 731300

tacitus
Posted on: Jul 25 2010, 05:32 AM


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QUOTE
These are all CANDIDATES. The Kepler team has said they expect that as many as 50% of the CANDIDATES are false alarms (eclipsing binaries, etc.)

That's what happens when people start quoting headlines from The Daily Mail. Never a good idea on any type of science forum.

blink.gif
  Forum: Telescopic Observations · Post Preview: #162575 · Replies: 1264 · Views: 731300

tacitus
Posted on: May 27 2010, 05:00 PM


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QUOTE (Tesheiner @ May 26 2010, 10:44 AM) *
Around 55m ESE. We'll better wait for a few additional moves to confirm this trend but I think (or wish) they'll move east whenever possible from now on.

Seems to me that continuing on the same track is almost certain at this point. Directly to the south of the current track there is an area of sand where there is no exposed bedrock at all. It looks like there could be an old crater under there, and if the sand is a little deeper as a result, then there really is little option but to continue ESE for another 100m or more.
  Forum: Opportunity · Post Preview: #160256 · Replies: 327 · Views: 216033

tacitus
Posted on: Apr 1 2010, 06:49 AM


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You have no soul, CosmicRocker smile.gif
  Forum: Spirit · Post Preview: #157915 · Replies: 311 · Views: 374618

tacitus
Posted on: Apr 1 2010, 12:00 AM


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Hibernation begins (probably)

QUOTE
PASADENA, Calif. -- NASA's Mars Exploration Rover Spirit skipped a planned communication session on March 30 and, as anticipated from recent power-supply projections, has probably entered a low-power hibernation mode.

http://www.jpl.nasa.gov/news/news.cfm?rele...ml&rst=2540
  Forum: Spirit · Post Preview: #157904 · Replies: 311 · Views: 374618

tacitus
Posted on: Mar 8 2010, 06:49 PM


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So what's the goal of the circumnavigation of this crater? Is it to study the splash pattern surrounding it, or are they looking for a candidate rock for a close-up study?
  Forum: Opportunity · Post Preview: #156693 · Replies: 409 · Views: 243517

tacitus
Posted on: Jan 26 2010, 06:42 PM


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Well, assuming that Spirit survives the winter, there will eventually come a time where, no matter how interesting Troy is, there will be diminishing science returns, and they will turn their minds to other objectives. Even being able to drag itself a few meters over a couple of months would allow Spirit to reach new locations and more science to be done.

So, I suspect they will continue to work on various scenarios behind the scenes even if their official position is that Spirit is now a stationary platform. It's better to be realistic than to be overly optimistic.
  Forum: Spirit · Post Preview: #154184 · Replies: 992 · Views: 639233

tacitus
Posted on: Jan 26 2010, 06:28 PM


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Well, we can still hope for an "accidental extrication."

But it sounds like this extrication thread's days are numbered.
  Forum: Spirit · Post Preview: #154181 · Replies: 992 · Views: 639233

tacitus
Posted on: Jan 26 2010, 06:21 PM


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You've got to hand it to Steve Squyres. I don't know anyone else who could sell a major reduction in Spirit's capabilities as a ground-breaking, exciting opportunity quite so effectively.
  Forum: Spirit · Post Preview: #154178 · Replies: 992 · Views: 639233

tacitus
Posted on: Nov 25 2009, 08:16 PM


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QUOTE (Holder of the Two Leashes @ Nov 24 2009, 03:12 PM) *
The third safing event, no science lost as this was just before a successful download.


I was initially worried that the safing events would create too many gaps in the data for transits to fall into, but I guess that the odds of them losing more than one instance of the same planetary transit are small, and should they discover that two other transit instances line up with one of the gaps in the data, they can infer that there likely was a transit during that time.

Not long now before the first full science results are released -- a couple of months away, or so.
  Forum: Telescopic Observations · Post Preview: #150832 · Replies: 1264 · Views: 731300

tacitus
Posted on: Nov 25 2009, 08:11 PM


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There was no stall of the suspect wheel during the diagnostic drive, so it's full speed ahead (relatively speaking!) for the next 5m drive over the Thanksgiving weekend.
  Forum: Spirit · Post Preview: #150831 · Replies: 992 · Views: 639233

tacitus
Posted on: Nov 24 2009, 12:12 AM


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I still think the observations of the orbits of the stars tracking around the black hole at the center of the Milky Way is one of the most fascinating results from the whole history of astronomy. The vast majority of the observable Universe beyond our solar system is essentially unchanged over the span of a single lifetime in terms of movement anyway, yet here we have managed to build up a picture of multiple stars whizzing around the black hole in just a few short years.

http://www.astro.ucla.edu/~ghezgroup/gc/pi...erImage08.shtml

There is a link to the animation at the bottom of this page.
  Forum: Telescopic Observations · Post Preview: #150751 · Replies: 10 · Views: 10477

tacitus
Posted on: Nov 19 2009, 10:09 PM


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Very nice -- just shows how active (and deadly) the region is.
  Forum: Telescopic Observations · Post Preview: #150449 · Replies: 10 · Views: 10477

tacitus
Posted on: Nov 19 2009, 10:06 PM


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This looked extremely promising, though I guess we'll have to wait upon the official word on how they thought it went.
  Forum: Spirit · Post Preview: #150448 · Replies: 992 · Views: 639233

tacitus
Posted on: Nov 18 2009, 07:31 PM


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Given that they are expecting to drive many meters to get the couple of feet they need to get out of the trap, I think it's safe to say that the one second drive was all wheel spin, if such a minuscule turn can be called "spin"
  Forum: Spirit · Post Preview: #150375 · Replies: 992 · Views: 639233

tacitus
Posted on: Nov 13 2009, 06:44 AM


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This is the annotated version of the image -- the center of the galaxy is the black hole Sagittarius A.

http://hubblesite.org/newscenter/archive/r...mat/xlarge_web/

  Forum: Telescopic Observations · Post Preview: #149978 · Replies: 10 · Views: 10477

tacitus
Posted on: Nov 9 2009, 10:42 PM


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I would be surprised if they used the RAT on an isolated rock here. While there is always the "use it while you can" argument, I would think the science team would prefer to reserve RAT resources for future sites where they can study rock strata in situ, where they have a much better chance of determining another part of Mars's geological record.
  Forum: Opportunity · Post Preview: #149688 · Replies: 916 · Views: 424867

tacitus
Posted on: Nov 6 2009, 06:32 PM


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From the latest mission report

QUOTE
Random noise is present in all measurements and cannot be calibrated out. Therefore, strict requirements were placed on the design of Kepler’s spacecraft systems to limit random noise to a low level. Measurements taken in space confirm that Kepler meets its random noise requirements.

Systematic noise results from the imperfect nature of any measuring device. It represents the instrument’s “finger print” placed upon the measurement, and must be calibrated out of the data in post-processing on the ground. Because systematic noise depends on the specific characteristics of the instrument, the best calibration requires that the noise sources be characterized and modeled based on measurements made in space. The Kepler team has been developing the ground software to calibrate out the various systematic noise sources since launch, and this work will continue for a number of months. As each source of systematic noise is calibrated, fainter transit signals can be detected. Data collected from the spacecraft will be continually reprocessed as the ground software matures, revealing smaller and smaller planets. This is a normal process and has been part of the Kepler plan since before launch. Fortunately for Kepler, the worst sources of systematic noise affect only a small portion of the field of view, so the majority of the field of view will be calibrated earlier, enabling small planets to be detected sooner.

So we finally get it from the horse's mouth. It's still short on the specifics, but they are essentially telling us that:

i) The worst sources of noise are restricted to a small number of detectors.

ii) The raw data from Kepler can be processed and reprocessed as the sources of noise are characterized and countered. This holds true for the worst affected detectors though it will take more time to clean up those signals, and thus a delay in finding a minority of the detectable Earth-sized planets.

No doubt one can surmise that the noisier channels will never be made as clean as the better behaving channels, but they still seem to be implying that they will be able to squeeze Earth-sized planets out of all the data eventually.

It should help that the majority of transits with periods much shorter than a year will not fall on the same detectors so, for example, if one transit of a planet with a 3 month orbit hits a noisy detector, there will three other transits detected by low noise channels, thus the team will know where to look for a transit in the noisy data too. That should help calibrate and confirm their "noise abatement" algorithms as they proceed.
  Forum: Telescopic Observations · Post Preview: #149416 · Replies: 1264 · Views: 731300

tacitus
Posted on: Nov 5 2009, 03:27 AM


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I think your avatar kind of gave that away smile.gif
  Forum: Telescopic Observations · Post Preview: #149297 · Replies: 1264 · Views: 731300

tacitus
Posted on: Nov 4 2009, 07:47 PM


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The Kepler press kit doesn't mention the word "twin" but it's clear that they are distinguishing between Earth-like (or Earth-sized) planets orbiting M class stars (red dwarfs) and those orbiting Sun-like stars:

QUOTE
Approximately in December 2010, scientists expect to announce any discoveries they have made in the
first year. This will be the first possible announcement of Earth-size planets in the habitable zones of
M-type stars
, which are stars smaller and cooler than the sun.

Discovery of Earth-size planets in Earth-like orbits requires nearly the full lifetime of the 3.5 year mission,
although in some cases three transits are seen in just a little more than two years. Other results that
require the full 3.5 years of data are: Planets as small as Mars in short period orbits, which utilizes the
addition of dozens or more transits to be detectable; and the detection of giant-inner planets that do not
transit the star, but do periodically modulate the apparent brightness due to reflected light from the planet.

Approximately in December 2011, scientists are expected to announce any discoveries made during the
first two years of the mission. The announcement will be made at NASA Headquarters and later at the
January 2012 American Astronomical Society (AAS) meeting held in Seattle, Wa., as well as at NASA’s
Ames Research Center. This will be the first possible announcement of Earth-size planets in the habitable
zones of K-type stars.

Around December 2012, scientists are expected to announce any discoveries made during the first
three years of the mission. The announcement will be made at NASA Headquarters and later at the AAS
meeting held in Austin, Texas, as well as at NASA’s Ames Research Center. This is the first possible
announcement of Earth-size planets in the habitable zones of solar-like or G stars.


It's the December 2010 announcements that will be impacted most by the faulty amplifiers, but assuming they can successfully filter out the signal noise introduced by those amps, detection of the affected transits will only be delayed, not lost.

Hey, I just realized that if all goes well they could be announcing the first "Earth-twin" in my home town in Dec 2012. I wonder if they would notice a non-astronomer sneaking in at the back?
  Forum: Telescopic Observations · Post Preview: #149269 · Replies: 1264 · Views: 731300

tacitus
Posted on: Nov 4 2009, 07:27 PM


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I believe they deem an Earth-twin to be an Earth-like planet orbiting a Sun-like star in the habitable zone -- which necessarily means that the planet's orbit will take about a year, give or take a month or two.

They are hoping to find Earth-like planets around other stars -- notably cooler stars than our Sun, like red dwarfs, where the habitable zone is closer in. It is the detection of these planets, with orbits of perhaps only 3 to 6 months that will be most affected by the delay in data processing, since if there were no glitchy amplifiers, they should be detectable before the software fix is available in 2011.

But if all the transits of such planets are caught by the detectors with clean amplifiers, then there is still a chance that they will be able to announce some discoveries of this type next year, but remember that the spacecraft is rotated 90 degrees every three months, increasing the chances that at least one of the three required transits will by masked by a glitchy amplifier, and thus detection will be delayed until the fix is available.
  Forum: Telescopic Observations · Post Preview: #149268 · Replies: 1264 · Views: 731300

tacitus
Posted on: Nov 4 2009, 06:36 PM


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Good news:

QUOTE
Three of these channels are plagued by electronic noise that makes stars in their field of view appear to flicker – "like it's changing its brightness at a rapid rate", says Kepler chief scientist William Borucki of NASA's Ames Research Center in Moffett Field, California.

The tiny brightness dips from a transiting Earth-size planet could be lost amid these fluctuations. But since the problem affects only a few of the 84 channels, it is not expected to hide all Earth-size planets, Borucki says.

"People have found a pimple here and they are trying to make it into a mountain," he told New Scientist. "A lot of the planets will show up regardless."

...

The team is developing software to automatically remove the noise from data after it is sent down to Earth, but rigorous testing means it will not be ready until 2011.


http://www.newscientist.com/article/dn1809...ien-earths.html

It's worth reading the whole article (I would quote more but that would be against the rules).
  Forum: Telescopic Observations · Post Preview: #149263 · Replies: 1264 · Views: 731300

tacitus
Posted on: Nov 3 2009, 11:23 PM


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One thing that exacerbates the problem is that the field rotates 90 degrees every three months, so even if the problem is contained within a small number of sensors (3 max) then that still means that up to 12 out of the 42 segments within the field will be affected. There does seem to be some confusion over how the software processing on board Kepler works -- some say that the processing integrates all the data across all sensors and amplifiers, and others are not so sure. I think we're going to have to wait for a detailed explanation from the Kepler team themselves, who are still claiming that it's not that bad a problem.
  Forum: Telescopic Observations · Post Preview: #149214 · Replies: 1264 · Views: 731300

tacitus
Posted on: Aug 12 2009, 12:50 AM


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A couple of questions. Given how nicely the first results from Kepler have turned out, should it be possible for Kepler to:

a] detect almost-but-not-quite transiting hot Jupiters from the rising and falling phase-induced light curves (i.e. like HAT-P-7b only without the transits).

b] detect the presence of other, non-transiting planets from variations in the timing of the transits of planets they can see?
  Forum: Telescopic Observations · Post Preview: #144641 · Replies: 1264 · Views: 731300

tacitus
Posted on: Aug 11 2009, 09:52 PM


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QUOTE
I'm quite curious to learn more about the light curves of some of the other variable stars, not necessarily curves which look like they may be planet transits. It sounds like they may have unique and exciting data. I wonder where and when these other data will be reported. Wouldn't it be something if it turns out that Kepler's Earth sized planets are a minor part of what its data yields?

The dataset all comes down together, so the timing of the non-exoplanet science results depends entirely upon the priority the science team gives it, and how many people they have working on it. It's probably not the highest priority, but if something highly unexpected falls out of the data, I suspect they will need to characterize fairly quickly it so they can rule out the possibility that it's caused by some type of exoplanet.

A non-exoplanet discovery would have to be really something to trump the discovery of habitable-zone Earth-twin planets. Unless it was something to do with solving current cosmological head-scratchers, like dark matter or dark energy, then I don't really know what would qualify as a show-stopper.

Discovering a Dyson's Sphere, perhaps.... smile.gif
  Forum: Telescopic Observations · Post Preview: #144621 · Replies: 1264 · Views: 731300

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