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Old 06-23-2009, 02:26 PM   #61
RisingFury
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Originally Posted by SiberianTiger View Post
 And I remember a NASA probe which was launched 3 years ago and will only start probing in 6 years from now. What a bally nuisance! I hope they'll improve their performance.

New Horizons?
Dude... it's headed for Pluto. Sure, it seems a long time to wait, but even at the "slow" speed it's traveling at, the Pluto flyby will be at over 13 km/s.

It's not like there's any point speeding it up or slowing it down anyway. It's not until 2015 that Pluto crosses the plane of the solar system... no sense launching it off plane...
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Old 06-24-2009, 07:49 PM   #62
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FYI, LCROSS is doing great. We hit our lunar periselene swingby target within about 1.5km which is excellent. The vehicle has checked out very well. Had some fun with the star tracker early on. Wen we started it up the first time, it failed to lock on stars which is always disconcerting - more disconcerting when it failed 3 times. Turns out we were failing because the Earth was still in the field of view which we suspected, but still nerve racking. Once we changed our attitude it worked fine. The only real issue we are having is with the thermal on two of our attitude control thrusters (1 and 7). The thermostats aren't tripping on the heaters at the expected set points, so the hydrazine in the thruster valves was in danger of freezing. We know the thermostats work because they came on prior before we primed the lines during startup. We suspect a thermal gradient from thruster valve to the thermostat with the thermostat being artificially warmed from the thruster catbed heaters. Solution is to move the vehicle attitude to a -20deg yaw (-Z) which puts the thruster thermal housings (we call the doghouses) into the sun. This is thermally stable and keeps the thrusters up in the 15-20degC range. We have also created some new fault management and loaded it onboard that is monitoring the thruster temps - it will fire the thrusters 1 second when they reach their cold alarm point (7degC) to induce a thermal response (fire both a + and - yaw that nulls any attitude response). This resets and can run every 5 minutes if necessary. In practice, it warms the thrusters enough that this only runs very 45min or so. We automated this to ensure that the vehicle will protect itself in case we are out of view or have a drop in comms. There is also an escalation that fires the thrusters for 5 seconds every 3 min if it trips the 4degC limit (immanent danger of freezing - thermistor and calibration polynomials are only accurate to +/-1.5degC, and hydrazine freezes at 1degC). We pushed it to this limit once hoping heaters would trip on, but no such luck - which s why we created the firing mitigations.

We also experienced considerable pertubations from the Centaur. The residual gasses in the tanks (primarily the LOX tank) leaked significantly through the FDVs (Filland drain valves) which produced considerable disturbance torque. This was expected, but we think the leak was larger than we expected and from more sources than expected. Net result was this forced us to use about 5kg of fuel per day for the first few days fight the diturbance. We also notice disturbance torque from the outgassing of the Centaur insulation foam - which is pretty highly water saturated in the Florida environment - all that water sublimating off into space is also pushing us around a bit. We are settling down now, disturbances are almost gone at this point, and we are using about 0.4kg/day just to maintain our steller inertial attitude.

Power is excellent, solar array is greatly outperforming specification - we are power positive at over 60deg array angle to the sun. Swingby was the first time we changed attitude enough to actually go on batteries.

We've experienced one cosmic ray hit on our memory, which was caught and corrected by the EDAC memory (single bit errory) and our 'memory scrub' routine which reads and writes memory continuously in about a 1 hour cycle.

The vehicle was tripped into safe mode Sunday due to an oversight. In rotating the vehicle around to try to find a thermaly safe attitude for the cold thrusters, after a shift changeover the oncoming team didn't realize the attitude rate limits were on when they attempted to slew to a new attitude - on-board fault management detected this manual change in attitude as a loss of attitude control and tripped itself into safe mode (I wasn't on console for this, but got called back in). Fun stuff, we know our fault management and safe mode work just fine now!!!

When we turned on the payload instruments for the lunar swingby, and the first moon picture popped up on the screen from the visible camera and the rainbow of colors from the mid-infrared (thermal) camera..... I must say it was awe inspiring.....
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Old 06-24-2009, 08:17 PM   #63
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It's so fascinating to read!.. Please, keep posting here!
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Old 06-24-2009, 09:39 PM   #64
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Originally Posted by SiberianTiger View Post
 It's so fascinating to read!.. Please, keep posting here!
I'll second that.

And let me reiterate my comment on one of the other threads here - the live webcast coverage of the swingby was outstanding - couldn't ask for more
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Old 06-24-2009, 10:16 PM   #65
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Thanks a ton also from my side to Likeshadow for the great insight.

@ Likeshadow: One question, I'm not sure if I have asked this before or if you can comment on it at all, but are there plans to eventually release the gathered data, specifically here the (global) elevation data (topographic map) to the public? I learned in a report shown on NASA TV, Google will benefit from the data in the form of using the elevation data for their application (GE or Google moon), however, will the (raw) data be available for us mortals as well? I am thinking about the ability to create a global hi-resolution DEM map of the moon (bumpmap in this case), which could be used in Orbiter to greatly increase the realism of the lunar topography. Also, do you know what the overalll global resolution will be of such a map? I suspect certain areas are scanned by the lasers with higher resolution than others, I may be wrong though.
Thanks for your feedback, keep the updates coming!
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Old 06-25-2009, 01:55 AM   #66
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Likeshadow, that was absolutely amazing to read, especially because it is a mission in progress. I hope you give us more of these updates and I wish you all the best with LCROSS and I wish you a nice bang in the end.

I am still struggling with the virtual LCROSS at the stage where I have to do a burn with IMFD to maximize the deflection (LCROSS orbit correction 1.) How many m/s should I expect to expend there?
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Old 06-25-2009, 02:33 AM   #67
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Quote:
Originally Posted by FordPrefect View Post
 
@ Likeshadow: One question, I'm not sure if I have asked this before or if you can comment on it at all, but are there plans to eventually release the gathered data, specifically here the (global) elevation data (topographic map) to the public?
I believe you are referring to the LRO data. This will be available via the
Planetary Data System. http://pds.jpl.nasa.gov/

Quote:
Originally Posted by Zeehond
  I am still struggling with the virtual LCROSS at the stage where I have to do a burn with IMFD to maximize the deflection (LCROSS orbit correction 1.) How many m/s should I expect to expend there?
That burn is the DV-1 burn I believe. It is a hard burn to judge, expecially with the encounter 2 1/2 orbits away, but should be about 18 m/s prograde.
It helps if you set the projection on the IMFD map display to periapsis, or maybe self.
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Old 06-26-2009, 04:37 PM   #68
mhs123
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[QUOTE=flying coffin;104378]I believe you are referring to the LRO data. This will be available via the Planetary Data System. http://pds.jpl.nasa.gov/

LCROSS data will be available via the PDS also. We hope to release
the swingby data by the end of July but can't guarantee that.

Originally, the thought was just to turn on the rocketcam as we did
the gravity asist to see what we would see. The swingby plan
expanded over time and has become very important for calibrating the
spectrometers, which are the real money instruments on LCROSS.

The interesting data will be from the impact. Our requirement is to
release everything by 6 months post impact, but we also hope to
release that considerably earlier.
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Old 06-29-2009, 01:03 AM   #69
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O-F Staff note: Non-development related posts have been moved here from the LRO/LCROSS addon development thread. Please post news and updates here.

---------- Post added at 11:03 ---------- Previous post was at 10:59 ----------

Where is LRO?
http://lroc.sese.asu.edu/whereislro/
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Old 06-29-2009, 01:14 AM   #70
Orbinaut Pete
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Good moon visible here tonight.

It's kinda surreal to look up at it, and know that LRO (with my name on board!) is now orbiting it.

I'm looking forward to the images that it will capture - the first of which will be publicly released in early July.
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Old 07-01-2009, 12:38 AM   #71
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LCROSS spotted by amateur astronomer:
http://lcross.arc.nasa.gov/
(click here to get an animated gif of it moving across the star field)
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Old 07-01-2009, 02:14 AM   #72
flying coffin
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That is very cool!

Anyone in AZ with a good telescope (all i've got is a crummy 4.5" reflector)
want to go out in the boonies Oct 9 to try to spot the impact?
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Old 07-01-2009, 10:09 AM   #73
BrianJ
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Nice! Looks like a spiral galaxy in that frame, too.

Some good info on observing LCROSS/Centaur during cruise here:
http://groups.google.com/group/lcros...-cruise-orbits

Also, LRO is now in nadir pointing mode and the LROC cameras have been powered up for a few hours:
http://lroc.sese.asu.edu/
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Old 07-01-2009, 11:56 AM   #74
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Quote:
Originally Posted by BrianJ View Post
 Nice! Looks like a spiral galaxy in that frame, too.
lol, actually that is a spiral galaxy. LCROSS is the streak beside it.
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Old 07-01-2009, 03:40 PM   #75
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 lol, actually that is a spiral galaxy. LCROSS is the streak beside it.
That's either an oblique comment about making ambiguous statements - or you really do think I'm dumber than a stick. Gave me a chuckle, either way!
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