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InSight Cruise Phase, Events during Mars transit prior to EDL
ollopa
post Nov 26 2018, 08:09 AM
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QUOTE (nprev @ Nov 26 2018, 07:39 AM) *
TCM update:

[i]"At 1:47 p.m. PST (4:47 p.m. EST) engineers successfully conducted a last trajectory correction maneuver to steer the spacecraft within a few kilometers of its targeted entry point over Mars. Engineers still need to conduct a last trajectory correction maneuver to steer the spacecraft toward its entry point over Mars.

Source



This seems very ambiguous. Does anyone have authoritative information that would clarify? Does the press release mean there is to be a TCM-6x at 12:42:27 UTC, or did they just forget to remove the reference to a "last trajectory correction" when they updated the post?

Also, can anyone remember if MPL and PHX used a TCM-6 or TCM-6x?
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nprev
post Nov 26 2018, 08:15 AM
Post #122


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Yeah, I don't know. Might be a bad edit on their part.

I don't really think that they have enough time left for another TCM because I'd assume that it'd take substantially more propellant to produce the same effect with every passing minute right now.

EDIT: Whups, missed Propguy's post above; much clearer. Thanks, man. Think it's all good, ollopa; no further TCMs, just entry parameter updates.

GO INSIGHT!!!


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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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propguy
post Nov 26 2018, 08:23 AM
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QUOTE (ollopa @ Nov 26 2018, 01:09 AM) *
This seems very ambiguous. Does anyone have authoritative information that would clarify? Does the press release mean there is to be a TCM-6x at 12:42:27 UTC, or did they just forget to remove the reference to a "last trajectory correction" when they updated the post?

Also, can anyone remember if MPL and PHX used a TCM-6 or TCM-6x?


See my post on the end of page 8. No additional TCM's will be conducted. PHX did not do a TCM6, but we only did it to ensure we were right on the center of the ellipse (all trajectory values pre-TCM6 met entry requirements, just being extra safe, which is a great idea). Got to get to bed to be ready for EDL. Hope you all enjoy the day tomorrow (actually later today). I am sure I will get my track record above 50/50 (MPL and PHX being my previous landing missions).
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dmuller
post Nov 26 2018, 08:26 AM
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QUOTE (ollopa @ Nov 26 2018, 07:09 PM) *
This seems very ambiguous. Does anyone have authoritative information that would clarify? Does the press release mean there is to be a TCM-6x at 12:42:27 UTC, or did they just forget to remove the reference to a "last trajectory correction" when they updated the post?

Yeah, propguy clarified in post #120. From what I've read, TCM-6X wouldnt have been more of a alternate or part 2 of TCM6 rather than clean up a TCM6 gone wrong.

Also, I see you quote "12:42:27 UTC" ... if you've taken that from my website, thanks for the visit, and a note that it was just my best guess based on descriptions I had ("so-and-so many hours before landing" which I took as "before EI" based on EI info I had at the time). I havent coded functionality yet for events that are not known (to me) to the second precise. If it was the actual time considered, that'd be spooky wheel.gif


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dmuller
post Nov 26 2018, 08:27 AM
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What time is Entry Interface, SpaceCraft Event Time, to the second precise? Does anybody here know


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dmuller
post Nov 26 2018, 12:28 PM
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I have MarCO closest approach numbers, inferred from what's in Horizons now:
CODE
MarCO-A 19:45:21 UTC SCET at 1,626km altitude
MarCO-B 19:47:45 UTC SCET at 1,750km altitude


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climber
post Nov 26 2018, 02:34 PM
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QUOTE (dmuller @ Nov 26 2018, 01:28 PM) *
I have MarCO closest approach numbers, inferred from what's in Horizons now:
CODE
MarCO-A 19:45:21 UTC SCET at 1,626km altitude
MarCO-B 19:47:45 UTC SCET at 1,750km altitude

Daniel, one important information is missing in your simulation timeline: Start eating Peanuts.


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nogal
post Nov 26 2018, 03:09 PM
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It was already late (so I couldn't do an update) when I found in YouTube the press conference video. At about 9:30 minutes into the video Tom Hoffman describes how the successive TCMs adjusted the landing ellipse ever closer to the intended target and shows (at about 10:25) the ellipse after TCM 5, which (center) was about 11 miles (ENE) away from the desired target location. So it was decided to perform another TCM, which has already been discussed in this thread.

For what it is worth, here is the InSight EDL file again (I have merged the two files from posts #87 and #93) including the target, the landing ellipse after TCM 5, and the EDL path now leading to the target.

Less than 5 hours now... GO, GO INSIGHT!

Attached File  InSight_EDL_Sim.kmz ( 18.87K ) Number of downloads: 42

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nprev
post Nov 26 2018, 04:01 PM
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Here we go! EDL thread is now live, please move discussion over there. NASA TV coverage will begin in three hours (1900 GMT).


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