Rosetta flyby of Asteroid Steins, 5th September 2008 |
Rosetta flyby of Asteroid Steins, 5th September 2008 |
Jun 19 2008, 06:53 AM
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#1
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Member Group: Members Posts: 571 Joined: 20-April 05 From: Silesia Member No.: 299 |
Only 78 days to Stein encounter ! I can't believe I forgot about this event.
-------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Jun 19 2008, 09:00 AM
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#2
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Member Group: Members Posts: 340 Joined: 11-April 08 From: Sydney, Australia Member No.: 4093 |
Indeed, almost there ... 78 days and 121 million km to fly. Currently 61 million km away from Steins: Rosetta Real-Time Simulation
Does anybody have more details on the flyby trajectory? I currently have it nailed down to minute precision with closest approach being on 05 Sep 2008 18:35 spacecraft event time at a distance of 712 km -------------------- |
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Jun 19 2008, 09:05 AM
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#3
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Senior Member Group: Members Posts: 3652 Joined: 1-October 05 From: Croatia Member No.: 523 |
Only 78 days to Stein encounter ! Anyone wanna bet if the previous flyby data (Earth, Mars) will hit the Planetary Science Archive before or after this flyby? -------------------- |
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Jun 19 2008, 10:01 AM
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#4
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Member Group: Members Posts: 571 Joined: 20-April 05 From: Silesia Member No.: 299 |
Anyone wanna bet if the previous flyby data (Earth, Mars) will hit the Planetary Science Archive before or after this flyby? PSA announcements: First release of Rosetta data - early 2008 ?? First release of Venus Express data - July 2008 !? Planetary Science Archive -------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Jun 19 2008, 10:11 AM
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#5
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Member Group: Members Posts: 655 Joined: 22-January 06 Member No.: 655 |
Perhaps it's time for a dedicated 'Steins' thread...
A few details on the rock: Main belt asteroid Discovered: November 4th 1969 Spectral type: E Diameter 4.6km |
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Jun 19 2008, 10:47 AM
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#6
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Senior Member Group: Members Posts: 3652 Joined: 1-October 05 From: Croatia Member No.: 523 |
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Jun 19 2008, 10:58 AM
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#7
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Founder Group: Chairman Posts: 14448 Joined: 8-February 04 Member No.: 1 |
They had previously been announced ( both of them, iiirc ) as being earlier. I would essentially ignore the announcement dates and just wait for stuff to actually arrive.
Alice data is already available upto and including the most recent Earth flyby. No other instrument has provided anything to date. Doug |
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Jun 21 2008, 09:23 AM
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#8
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
Some details about Steins that I collected for the third volume of my book "robotic exploration of the solar system"
Steins is a small body less than 10 km across, discovered on 4 November 1969 by Soviet astronomer N. Chernykh at the Nauchnyj Observatory in Crimea and named after Karlis Steins, former director of the Latvian University Astronomical Observatory. While the properties of Lutetia, the second asteroid target are relatively well known, being a largish and bright object discovered more than a century ago, almost nothing was known about Steins, and observational campaigns were started in 2004 to characterize it. Steins was observed by the largest astronomical observatory on Earth, including the European Very Large Telescope (VLT) in Chile, JPL's Table Mountain Observatory, the Spitzer infrared astronomy satellite and Rosetta itself. The Rosetta orbiter observed continuously Steins (1.06 AU away) for 24 hours with its science camera on 11 March 2006 in order to collect a “light curve” at phase angles larger than ever achievable from Earth, due to observational geometry constrains and for a longer time span, uninterrupted by day and night cycles. A total of 238 images were taken, covering four rotations. Although researchers initially catalogued Steins in the S class (like most previously-visited bodies), the observational campaigns found that its spectral and polarimetric properties placed it in the E taxonomic class of reddish bodies with high albedo believed to be thermally evolved and of igneous origin, which underwent at least a partial melting and differentiation early in their history. E asteroid spectra probably makes them related to some rare enstatite chondrite or aubrite meteorites and therefore these bodies are believed to have a surface consisting of iron-free or iron-poor silicates. Observations pinpointed Steins' rotation period at about 6.05 hours, while the measured diameter could vary between 2 and 5 km, depending on its albedo. Asymmetries in the light curve confirmed that the small body has an irregular shape, with a ratio between the main axes of about 1.3. Other researchers pointed out that some of the characteristics of Steins could hint at a young and very rough surface at most a few million years old. While fewer than 30 members of the E class of asteroids were known, including (44) Nysa, the largest, and two near-Earth objects, (3103) Eger and (4660) Nereus (a recurrent space mission target), little is known about the evolutionary history of the type. Steins was initially placed in the same family as (64) Angelina, but other studies showed that it shared most of the same spectral characteristics as Eger, both bodies being believed to be members of an old eroded family which formed in the inner asteroid belt close to the present position of Steins, which appears to be the largest member of the family. The presence of Eger in an Earth-intersecting orbit of course provides a path for enstatite and aubrite meteorites to hit our planet. The encounter on 5 September 2008 will be at a distance of 1745 km and a relative speed of 8.6 km/s |
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Jun 21 2008, 10:04 AM
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#9
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Junior Member Group: Members Posts: 57 Joined: 21-September 06 Member No.: 1172 |
Even more details for Rosetta fans !!!
Flyby in a nutshell:
Flyby strategy
Flyby Science:
Expected data volume:
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Jun 21 2008, 11:35 AM
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#10
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
Do we have any radar data indicating binary/satellite existence for any asteroid in this size range ?
Just wondering what the odds are for 'nother Dactyl type discovery. Would 200+ images for albedo study yield enough light curve data to rule out a satellite? Particularly one that was in an orbit inclined enough so that the satellite was never eclipsed or transited the primary. |
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Jun 21 2008, 03:31 PM
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#11
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Member Group: Members Posts: 242 Joined: 21-December 04 Member No.: 127 |
These sort of encounters always fascinate me...this is likely to be the only close approach data humanity collects on this particular hunk of rock for hundreds of years. Some time in the distant future an asteroid miner will pull up these old images on his way to this asteroid and wonder at the folks who sent a barbaric robot out to it....
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Jun 21 2008, 04:16 PM
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#12
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
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Jun 21 2008, 05:00 PM
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#13
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Merciless Robot Group: Admin Posts: 8789 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Do we have any radar data indicating binary/satellite existence for any asteroid in this size range ? Wasn't there an NEO radar-imaged by Aricebo that was a small binary object? It's certainly possible that Steins is binary or has a small satellite, but if so I suspect it would have to have been the product of a weak, recent impact event. There's not a lot of gravitation exerted by a 4.6 km body. -------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Jun 21 2008, 08:39 PM
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#14
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Interplanetary Dumpster Diver Group: Admin Posts: 4405 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
Wasn't there an NEO radar-imaged by Aricebo that was a small binary object? It's certainly possible that Steins is binary or has a small satellite, but if so I suspect it would have to have been the product of a weak, recent impact event. There's not a lot of gravitation exerted by a 4.6 km body. There has been a multitude of such objects. Castalia was the first one. Arecibo and Goldstone will be observing the upcoming flyby of 2008 BT18 (July 6 and 7 for Arecibo, July 11 for Goldstone]. It will pass about 2.3 million kilometers away and is 700 to 800 meters across, so we should get some nice images and, with some luck, maybe another binary. -------------------- |
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Jun 25 2008, 04:21 PM
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#15
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Member Group: Members Posts: 655 Joined: 22-January 06 Member No.: 655 |
Do we have any radar data indicating binary/satellite existence for any asteroid in this size range ? I couldn't find any relevant radar data, but it appears see here that a moon has been likely ruled out for Steins. |
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