Author Topic: NASA - Kepler updates  (Read 162487 times)

Online Robotbeat

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Re: NASA - Kepler updates
« Reply #200 on: 01/20/2013 04:34 AM »
I am no expert on aerospace bearings, either. But it does seem to be a limiting factor in a lot of spacecraft, almost as much as propellant (a problem which I think gets a lot more idle and non-idle brain cycles... people have thought up electric thrusters and refueling). How much research is there on longer life gyros? I haven't noticed any while examining SBIR solicitations, but that could be because I was more interested in things like electric thrusters, etc.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline ngc3314

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Re: NASA - Kepler updates
« Reply #201 on: 01/27/2013 07:44 PM »
One of the Kepler scientists visited our campus this week, and at lunch I rather indelicately brought up the reaction wheels. He had a couple of comments which surprised me. Apparently there are $105 reaction wheels and $106 reaction wheels, and the constant budget tradeoffs often mean that science missions use the $105 kind. A panel of acknowledged reaction-wheel experts convened to advise on how Kepler operations should react, and their experiences led to a wide divergence of opinion. I seem to recall hearing the phrase "black magic" at least once.

In hindsight, these often are the weak link in space observatory lifetimes (sometimes you have to dig a bit to distinguish between problems with the sensing units as distinct from the reaction wheels used to provide torque). Spares are obviously good - one interesting approach to avoid a complete set of spares is to add a fourth at an axis angled to each of the three primary ones, giving some control authority (with a new control law) along whichever axis has a failure first. For attitude sensing, star trackers can often provide equivalent information on some axes within a limited range - HST operated like this for several years so as to spin down one gyro as an effective spare, and both IUE and FUSE used this strategy to extend their usable lifetimes.

Online Robotbeat

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Re: NASA - Kepler updates
« Reply #202 on: 01/28/2013 02:34 AM »
That was a GREAT answer! Thanks!
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline LouScheffer

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Re: NASA - Kepler updates
« Reply #203 on: 01/28/2013 02:37 AM »
One of the Kepler scientists visited our campus this week, and at lunch I rather indelicately brought up the reaction wheels. He had a couple of comments which surprised me. Apparently there are $105 reaction wheels and $106 reaction wheels, and the constant budget tradeoffs often mean that science missions use the $105 kind.
This makes sense.  I found an AMSAT project that was developing magnetic bearing wheels for small satellites.  It said there were already 3  vendors for magnetic bearing wheels for big satellites, mostly geosynchronous.  Also here is an article about flown magnetic bearings in 1997:
http://articles.adsabs.harvard.edu//full/1997ESASP.381..649S/0000649.000.html
So it sounds like more reliable wheels do exist, so it's a budget and not a technology problem.

Offline LouScheffer

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Re: NASA - Kepler updates
« Reply #204 on: 01/28/2013 02:46 AM »
Apparently there are $105 reaction wheels and $106 reaction wheels, and the constant budget tradeoffs often mean that science missions use the $105 kind.

This would also explain why you often hear of reaction wheel failures on scientific craft, but seldom on geosynchronous satellites.   Here's another link to a vendor of such wheels, so they are definitely available.
http://www.rockwellcollins.com/sitecore/content/Data/Products/Space_Components/Satellite_Stabilization_Wheels/Magnetic_Bearing_Momentum_and_Reaction_Wheel.aspx
This one can also change its rotation axis by 1.7 degrees, so it can supply at least some control to the other axes.  This could be a huge help in providing graceful degradation in failure cases.

Offline LouScheffer

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Re: NASA - Kepler updates
« Reply #205 on: 01/30/2013 12:58 AM »
Sad to see Kepler having problems.  Arguably the best SMD mission I have watched from inception to launch and mission execution.

OK, after letting the reaction wheels rest for 10 days, they've restarted them.  So far, so good, but keep your fingers crossed....
http://www.nasa.gov/mission_pages/kepler/news/keplerm-20132901.html

Offline Star One

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Re: NASA - Kepler updates
« Reply #206 on: 02/20/2013 05:42 PM »
Quote
The discovery of a strange new world about the size of Earth's moon has shattered the record for the smallest known alien planet, scientists say.

The newfound alien planet Kepler-37b is the first exoplanet discovered to be smaller than Mercury. It whips around its parent star every 13 days and has a roasting surface temperature of about 800 degrees Fahrenheit (427 Celsius), researchers said. It not a promising contender for life, they added.

Astronomers found Kepler-37b and two other, larger planets (called Kepler-37c and Kepler-37d) orbiting a star about 215 light-years from Earth using NASA's prolific Kepler space telescope. Finding such a small exoplanet with the Kepler spacecraft was a stretch, but some attributes of Kepler-37b's parent star made the discovery possible.

http://www.space.com/19874-smallest-alien-planet-moon-size.html

Offline Quindar Beep

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Re: NASA - Kepler updates
« Reply #207 on: 02/20/2013 06:35 PM »
Quote
The discovery of a strange new world about the size of Earth's moon has shattered the record for the smallest known alien planet, scientists say.

This is actually over-stating what the scientists said. They were pretty careful to add the qualifier "around a sun-like star". PSR B1257+12A is still the record-holder for smallest planet (it's about half the size of Kepler-37b), but it's an oddball -- a pulsar planet, which class of planets is probably formed differently from regular planets and is thus a rather different beast.

Offline Hungry4info3

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Re: NASA - Kepler updates
« Reply #208 on: 02/20/2013 07:26 PM »
PSR B1257+12A is still the record-holder for smallest planet (it's about half the size of Kepler-37b)

It's size is completely unknown. Only a minimum mass is known. Being at least twice as massive as our Moon, it could very well be physically larger than Kepler-37b.
« Last Edit: 02/20/2013 07:27 PM by Hungry4info3 »

Offline Robert Thompson

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Re: NASA - Kepler updates
« Reply #209 on: 03/30/2013 04:37 PM »
http://www.hadrosaur.com/kepler.html

"Thirteen stories about distant worlds that really exist

A new anthology of action-packed, mysterious, and humorous stories all based on real planets discovered by the NASA Kepler mission. Edited by and contributing stories are David Lee Summersóbest selling author of Owl Dance, The Pirates of Sufiro, and other novelsóand Steve B. Howell, project scientist for the Kepler mission. Whether on a prison colony, in a fast escape from the authorities, or encircling a binary star, thirteen exoplanet stories written by authors such as Mike Brotherton, Laura Givens, and J Alan Erwine will amuse, frighten, and intrigue you while you share fantasy adventures among Kepler's real-life planets.

Projected ship date: June 15, 2013 "

Offline jacqmans

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Re: NASA - Kepler updates
« Reply #210 on: 04/15/2013 06:30 PM »
MEDIA ADVISORY: M13-062

NASA HOSTS MEDIA BRIEFING TO DISCUSS KEPLER PLANETARY DISCOVERY

WASHINGTON -- NASA will host a news briefing at 2 p.m. EDT, Thursday,
April 18, to announce new discoveries from the agency's Kepler
mission.

The briefing will be held in the Syvertson Auditorium, Building N-201,
at NASA's Ames Research Center in Moffett Field, Calif., and be
broadcast live on NASA Television and on the agency's website.

Kepler is the first NASA mission capable of finding Earth-size planets
in or near the habitable zone, which is the range of distance from a
star where the surface temperature of an orbiting planet might be
suitable for liquid water. Launched in 2009, the Kepler space
telescope is detecting planets and planet candidates with a wide
range of sizes and orbital distances to help us better understand our
place in the galaxy.

The briefing participants are:

-- Paul Hertz, astrophysics director, NASA Headquarters, Washington
-- Roger Hunter, Kepler project manager, Ames
-- William Borucki, Kepler science principal investigator, Ames
-- Thomas Barclay, Kepler scientist, Bay Area Environmental Research
Institute, Sonoma, Calif.
-- Lisa Kaltenegger, research group leader, Max Planck Institute for
Astronomy, Heidelberg, Germany, and research associate,
Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.

News media representatives may attend in-person or by teleconference.
To register or obtain dial-in information, contact Michele Johnson at
650-604-4789 or michele.johnson@nasa.gov by noon EDT Thursday, April
18.

To reach Ames, take U.S. Highway 101 to the Moffett Field-NASA Parkway
exit and drive east toward the main gate. Media representatives must
obtain a badge at the Visitor Badge Office, located at the main gate.


News media representatives and the public may submit questions via
Twitter to #AskNASA.

For NASA TV streaming video, scheduling and downlink information,
visit:

http://www.nasa.gov/ntv

The event also will be streamed live on Ustream at:

http://www.ustream.tv/channel/nasa-arc

For more information about the Kepler mission and to view the digital
press kit, visit:

http://www.nasa.gov/kepler

Online Chris Bergin

Re: NASA - Kepler updates
« Reply #211 on: 04/15/2013 06:34 PM »
Could be exciting!

Offline catdlr

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Re: NASA - Kepler updates
« Reply #212 on: 04/16/2013 11:13 PM »
Second media advisory with streamed video links:

Advisory: 2013-137                                                                   
April 16, 2013

NASA Hosts Media Briefing on Kepler Planetary Discovery



The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2013-137&cid=release_2013-137

PASADENA, Calif. -- NASA will host a news briefing at 11 a.m. PDT (2 p.m. EDT), Thursday, April 18, to announce new discoveries from the agency's Kepler mission.

The briefing will be held at NASA's Ames Research Center in Moffett Field, Calif., and will be broadcast live on NASA Television and on the agency's website.

The briefing will also be streamed live at: http://www.ustream.tv/NASAJPL2, with a moderated Web chat featuring Kepler Deputy Project Scientist Nick Gautier of NASA's Jet Propulsion Laboratory, Pasadena, Calif. The briefing will also be broadcast live at: http://www.ustream.tv/channel/nasa-arc .

Kepler is the first NASA mission capable of finding Earth-size planets in or near the habitable zone, which is the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water. Launched in 2009, the Kepler space telescope is detecting planets and planet candidates with a wide range of sizes and orbital distances to help us better understand our place in the galaxy.

The briefing participants are:

-- Paul Hertz, astrophysics director, NASA Headquarters, Washington
-- Roger Hunter, Kepler project manager, Ames Research Center, Moffett Field, Calif.
-- William Borucki, Kepler science principal investigator, Ames Research Center
-- Thomas Barclay, Kepler scientist, Bay Area Environmental Research Institute, Sonoma, Calif.
-- Lisa Kaltenegger, research group leader, Max Planck Institute for Astronomy, Heidelberg, Germany, and research associate, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.


News media representatives and the public may submit questions for the news conference participants via Twitter to #AskNASA.

For NASA TV streaming video, scheduling and downlink information, visit: http://www.nasa.gov/ntv .

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

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

Michele Johnson 650-604-4789
Ames Research Center, Moffett Field, Calif.
michele.johnson@nasa.gov

J.D. Harrington 202-358-5241
Headquarters, Washington
j.d.harrington@nasa.gov

- end -
« Last Edit: 04/16/2013 11:14 PM by catdlr »
Tony De La Rosa

Offline jcm

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Re: NASA - Kepler updates
« Reply #213 on: 04/17/2013 12:52 AM »
Could be exciting!

Yes - I think you will find their results to be of interest.
-----------------------------

Jonathan McDowell
http://planet4589.org

Offline Robert Thompson

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Re: NASA - Kepler updates
« Reply #214 on: 04/17/2013 04:35 AM »
Hi Prof McDowell,

I spoke with you at some length at the Long Beach AAS at the exoplanet poster Hot Jupiter WASP-77Ab. Ian Crossfield of Max Planck initiated collaboration with our UA Astronomy Club and we have taken two full and three partial transits of M-dwarf Hot Neptune GJ3470b on our 61" Kuiper telescope. The Junior I stood beside (Lauren, WASP-26b) is going to be Ian's lead author on a large collaborative paper for GJ3470b. Just letting you know your encouragement bears fruit. Fund me, maybe? :)

Robert Thompson
B.S. Astronomy UA Steward Observatory

Regarding Kepler, my adviser has said, curiously, that Kepler should have already found the TTVs indicating hot Jupiter moons, but has not, and that this should be concerning. Is he misinformed regarding detection limits and/or minimum integration time?

Offline Hungry4info3

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Re: NASA - Kepler updates
« Reply #215 on: 04/18/2013 12:49 PM »
Regarding Kepler, my adviser has said, curiously, that Kepler should have already found the TTVs indicating hot Jupiter moons, but has not, and that this should be concerning. Is he misinformed regarding detection limits and/or minimum integration time?

It's not likely a detection limit issue, but a physical limits issue on the existence of moons orbiting hot Jupiters. Hot Jupiters have very small Hill Spheres (because they are so close to their stars), so any exomoons would need to orbit very closely to the planet.

With hot Jupiters (almost certainly) being tidally locked to the star, they have rotation periods on the order of a couple days. This places the synchronous orbit radius around a hot Jupiter well above the Hill sphere radius. Therefore, any exomoons around hot Jupiters will have their orbits tidally decay, depositing the exomoon into the planet. Decreasing the exomoons mass gives it some more time, but the mass we're talking about to permit the longevity of the exomoon to exist to the current day tends to be on the order of Phobos-sized bodies.

I do not expect Kepler to discover hot Jupiter exomoons. Not because of technical reasons, but because I simply do not expect detectable exomoons around hot Jupiters to exist.

Edit: Clarifications
« Last Edit: 04/18/2013 01:02 PM by Hungry4info3 »

Offline Robert Thompson

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Re: NASA - Kepler updates
« Reply #216 on: 04/18/2013 01:59 PM »
Huh, I thought I was typing a question, 'moons around Jupiters in the habitable zones'.  :-X Thank you, Hungry4info3. (I've known what you are explaining.) How about that question, but with respect to Jupiter+ mass planets in habitable zones, ~1 AU around ~G stars. I.e., should it be concerning that not one exomoon has been found? I don't know if there have been any exomoon candidates / KOI.

Offline Hungry4info3

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Re: NASA - Kepler updates
« Reply #217 on: 04/18/2013 02:14 PM »
Ahh, understood!  :D

Here's a fairly recent paper about habitable exomoon detection. It looks like it may be feasible for moons of particularly high mass, but such massive moons aren't really what you would expect to find anyway.
http://arxiv.org/abs/1304.2925

This paper found some tentative exomoon host candidates (though this explanation is in no way unique).
http://arxiv.org/abs/1207.7229

Finding exomoons through their transits of course doesn't work because the changing position of the exomoon around the planet makes it hard to just stack transits. On the other hand, the transits of exomoons could inject noise in stacked lightcurves centred on the planet.
http://arxiv.org/abs/1108.4557
« Last Edit: 04/18/2013 02:18 PM by Hungry4info3 »

Offline jcm

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Re: NASA - Kepler updates
« Reply #218 on: 04/18/2013 04:12 PM »
Hi Prof McDowell,

I spoke with you at some length at the Long Beach AAS at the exoplanet poster Hot Jupiter WASP-77Ab. Ian Crossfield of Max Planck initiated collaboration with our UA Astronomy Club and we have taken two full and three partial transits of M-dwarf Hot Neptune GJ3470b on our 61" Kuiper telescope. The Junior I stood beside (Lauren, WASP-26b) is going to be Ian's lead author on a large collaborative paper for GJ3470b. Just letting you know your encouragement bears fruit. Fund me, maybe? :)

Robert Thompson
B.S. Astronomy UA Steward Observatory

Regarding Kepler, my adviser has said, curiously, that Kepler should have already found the TTVs indicating hot Jupiter moons, but has not, and that this should be concerning. Is he misinformed regarding detection limits and/or minimum integration time?

Hi Robert, of course I remember talking with you and Lauren at AAS.
That's great news about the transits.
I only wish I had funding! I just learnt that the postdoc who did most of the actual work on the exciting Kepler results to be announced today hasn't been able to get a new position and is considering leaving the field - it's a bit of a depressing time. But I am optimistic that by the time you guys get your PhDs the economic pendulum will have swung back again.
-----------------------------

Jonathan McDowell
http://planet4589.org

Offline Star One

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Re: NASA - Kepler updates
« Reply #219 on: 04/18/2013 06:03 PM »
Quote
We're a step closer to knowing if our galaxy is home to a multitude of planets like Earth or if we are a rarity. The three habitable zone super-Earth-size planets are in two systems containing a total of seven newly discovered planets:

http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=243

Tags: updates