Mro On Approach, TCM-3 not required |
Mro On Approach, TCM-3 not required |
Mar 10 2006, 08:02 AM
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#151
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Member Group: Members Posts: 370 Joined: 12-September 05 From: France Member No.: 495 |
Watch Mars Reconnaissance Orbiter's Doppler Plot in real time during MOI !
http://marsprogram.jpl.nasa.gov/mro/mission/tl_doppler.html Mars Orbit Insertion - Sequence of Events http://marsprogram.jpl.nasa.gov/mro/mission/tl_moi-soe.html |
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Mar 10 2006, 08:20 AM
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#152
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Junior Member Group: Members Posts: 48 Joined: 10-February 05 Member No.: 166 |
Watch Mars Reconnaissance Orbiter's Doppler Plot in real time during MOI ! http://marsprogram.jpl.nasa.gov/mro/mission/tl_doppler.html Mars Orbit Insertion - Sequence of Events http://marsprogram.jpl.nasa.gov/mro/mission/tl_moi-soe.html Why is the small version of the Doppler plot different from the large one? And what is the discontinuity? Borek |
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Mar 10 2006, 11:03 AM
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#153
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Newbie Group: Members Posts: 18 Joined: 12-February 04 Member No.: 28 |
I don't think the small one is live - at least, it hasn't changed in some minutes.
The discontinuity was labelled 'DSS 15 Handover' - I suppose this is when the DSN reception is being passed from one dish to the next. Due to the rotation of the Earth, any given dish will have some additional velocity towards Mars as it (Mars) appears above the horizon; When Mars sets, the DSN dish is moving away from Mars at a similar velocity. This means that the DSN station doppler is added to the MRO doppler; the DSN doppler is at its strongest, but in opposite directions, at handover. Anyway, that's my take on it. --Martin |
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Mar 10 2006, 11:52 AM
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#154
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Newbie Group: Members Posts: 6 Joined: 10-March 06 From: France Member No.: 698 |
Hi everybody!
New to this board, although I have been lurking through these pages since the very beginning. I have been bitting my nails on my own on MODY's MOI in 2001, then again for Spirit's and Oppy's arrival in 2004. So today, on MRO's MOI I have chosen to bite my nails in good company. In excellent company. Go MRO!! |
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Mar 10 2006, 03:14 PM
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#155
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Member Group: Members Posts: 624 Joined: 10-August 05 Member No.: 460 |
Watch Mars Reconnaissance Orbiter's Doppler Plot in real time during MOI ! http://marsprogram.jpl.nasa.gov/mro/mission/tl_doppler.html Mars Orbit Insertion - Sequence of Events http://marsprogram.jpl.nasa.gov/mro/mission/tl_moi-soe.html Utterly cool. We are seeing a sawtooth in the residuals @ ~6 minute intervals - is this due to attitude control, solution harmonics or what? |
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Mar 10 2006, 05:01 PM
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#156
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
Utterly cool. We are seeing a sawtooth in the residuals @ ~6 minute intervals - is this due to attitude control, solution harmonics or what? Interesting item from 2001 Mars Odyssey orbit determination during interplanetary cruise: The resolution of the graph makes it hard to read, but it look like the amplitude of the sawtooth is a bit larger than with MRO (~5x), and the period about 15 minutes. QUOTE During the TCM-2 data arc, a couple passes of Doppler
residuals such as that shown in Figure 5 exhibited a peculiar sawtooth pattem. Because it appeared that we were having problems fitting the data without the gasleak acceleration estimation, we became concerned that this may have been more evidence of serious problems in the SIC modeling, the SDST, DSN hardware or the ODP. Several DSN and NAG experts helped analyze these unusual patterns, but no definitive explanation was found. The DSN tracking procedures for Odyssey had been to follow the S/C’s downlink frequency within a fairly tight bandwidth by periodically ramping the uplink signal. It was believed that this ramping of the signal could have contributed to this problem, especially if the values of the ramp rates were being truncated, but no evidence of this was found. In the case that this data was incorrect, our procedures were to remove the data, however, it was determined that the data had little effect on the OD solutions, especially due to the signatures’ high fi-equency nature. -------------------- |
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Mar 10 2006, 05:14 PM
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#157
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Member Group: Members Posts: 370 Joined: 12-September 05 From: France Member No.: 495 |
There was a final TCM planned (if needed) at 15:24 UTC.
No change is visible on the doppler, so I guess it was cancelled (or too small to be seen). -- Rakhir |
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Mar 10 2006, 05:16 PM
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#158
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
Press conf is on now - they did no TCM5
Doug |
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Mar 10 2006, 05:40 PM
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#159
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Member Group: Members Posts: 624 Joined: 10-August 05 Member No.: 460 |
Interesting item from 2001 Mars Odyssey orbit determination during interplanetary cruise: The resolution of the graph makes it hard to read, but it look like the amplitude of the sawtooth is a bit larger than with MRO (~5x), and the period about 15 minutes. Thanks - this is a good read, and the unmodel aspect - small forces corrections - required to hit the target make the cancelation of the finally 3-4 corrections very impressive navigation! Oh, and the saw tooth? Still an unsolved mystery:) |
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Mar 10 2006, 05:55 PM
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#160
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
Comparing two NASA MRO prediction kernels, one for ideal MOI and one for no MOI, gives these predicted times (Earth-received UTC):
loss-of-signal: 21:46:09 MOI, 21:46:09 no-MOI (no difference) aquisition-of-signal: 22:16:00 MOI, 22:08:56 no-MOI (no-MOI AOS being 7:04 earlier) So when looking at the doppler plot, LOS should happen at 21:46:09 UTC regardless, and hopefully AOS will not be before 22:16:00 UTC. The time between 22:08:56 to 22:16:00 would be the critical time. I suppose that anything much after 22:16:00 would indicate too much of a burn. -------------------- |
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Mar 10 2006, 06:14 PM
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#161
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Junior Member Group: Members Posts: 86 Joined: 12-October 05 From: Beijing Member No.: 526 |
Mars Reconnaissance Orbiter was only 50000 kilometers away from Mars at 2006-03-10 17:25:55 UTC.
velocity = 3.111 km/s range-rate = -3.082 km/s |
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Mar 10 2006, 06:57 PM
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#162
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Chief Assistant Group: Admin Posts: 1409 Joined: 5-January 05 From: Ierapetra, Greece Member No.: 136 |
Hi guys, can I join the party?
-sitting on edge of seat for the coming hours as you all are I'm sure Nico -------------------- photographer, space imagery enthusiast, proud father and partner, and geek.
http://500px.com/sacred-photons & |
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Mar 10 2006, 07:10 PM
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#163
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
Feel free to join the rave
http://www.unmannedspaceflight.com/index.p...view=getnewpost There's a big crowd..well.....3 of us Doug |
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Mar 10 2006, 07:18 PM
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#164
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Newbie Group: Members Posts: 18 Joined: 12-February 04 Member No.: 28 |
Don't worry, we'll be watching when the time comes.
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Mar 10 2006, 07:24 PM
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#165
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Member Group: Members Posts: 178 Joined: 13-September 05 Member No.: 498 |
3 is a crowd, anyway.
So that's three TCMs all unneeded leading up to an orbit insertion burn. That is just an awesome performance, and if I were superstitious (which I'm not, touch wood) I would hope we haven't used up our luck early. |
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