KBO encounters |
KBO encounters |
Aug 2 2008, 12:53 PM
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#1
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Newbie Group: Members Posts: 6 Joined: 1-August 08 Member No.: 4280 |
Hi,
I’m regular follower of NH and I’m also interested in the 2nd leg of the mission, i.e the 2016+ KBOs encounters. Does anyone know when operations about this leg (starting with searching objects of interest with HST or some other earth-based means, I suppose) are expected to begin ? |
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Aug 23 2012, 04:13 AM
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#2
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Member Group: Members Posts: 701 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
Right, our camera aperture is small enough that even though we're closer to the KBOs there's no advantage to searching from the spacecraft. Plus our maximum exposure time is 10 seconds compared to the hours we can integrate from the ground, and it takes thruster fuel to hold the spacecraft steady during those 10 second exposures, so we can't take too many of them. Oh, and because of the need to use thrusters to hold the spacecraft steady, our best spatial resolution for those long exposures is about 4 arcseconds, compared to the ~0.6 arcseconds we can get from the Earth (on a good night). The lower spatial resolution makes it difficult to distinguish and KBOs from all the background stars.
New Horizons would have a sensitivity advantage for KBOs that are very small and close to the spacecraft, as algorimancer says, but we don't think there are many of those, and we don't have the onboard smarts to find them autonomously in the images onboard the spacecraft, and we don't have the bandwidth to send enough of them back to Earth for processing even if we could afford the fuel for all those long exposures... So we'll just have to keep searching with the big telescopes here on Earth. John |
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Aug 23 2012, 01:10 PM
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#3
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
...need to use thrusters to hold the spacecraft steady....don't have the onboard smarts to find them autonomously in... Thanks for clearing that up. I had assumed that reaction wheels were used for adjusting orientation, if thrusters are needed this is clearly a non-starter. I was also a bit concerned that communication would require re-orienting to point at Earth, which would add additional complications. Perhaps someday a similar approach might be tried on a subsequent mission. |
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