MRO MOI Events Timeline, Time Zone Friendly Options

[djellison]

Z = GMT / UT, P = Pacific
Future, Unconfirmed, Confirmed

NASA TV coverage starts at 2030Z / 1230P

TCM5 was not required.
2049Z / 1249P - Tank Pressurize - nominal pressure reported (@2053Z)
2103Z / 1303P - Switch to LGA ( 2 way doppler @ 2104Z, Lock at 160bps :2105Z)
2107Z / 1307P - Turn to Burn attitude (start of turn confirmed via doppler & telem @2110Z - Slew finished @2119Z via ACS)
2124Z / 1324P - Start of MOI Burn (confirmed via Doppler @2123Z )
(tank pressure about 3psi below predicts but within margins @2131Z )
(307m/sec accumulated delta @2135Z)
(401m/sec accumulated delta @2139Z)
(588m/sec accumualted delta @2144Z)
(telem. indicated eclipse entry @2146Z)
2146Z / 1346P - Loss of signal ( confirmed on doppler @2147Z- actual time 21:46:23Z)
2151Z / 1351P - Nominal End of Burn
2216Z / 1416P - Nominal AOS - (signal aquired - 1 way doppler @2116Z - 22:16:08 actual time)
(2 way doppler @2223Z)
2230Z / 1430p - 1641m/s burn indicated by telementry.

MRO is now orbiting the planet Mars

Status check at 2245Z
Flight Software - Burn done at 20% Utilisation
Prop Nominal
ACS, Earth point on reaction wheels, Star tracker aquisition ( 8 stars ), Burn time 1641 seconds vs 1606 expected. 1000.48 m/s compared to 1000.36m/s expected.
Thermal - all temps nominal. A few alarms due to soak back from the rcs thrusters.
EPS - Nomincal, trickle charging batts ( 110% state of charge ) - 870 Watts being used, 1650 Watts available from arrays.
Telecom - Nominal, on primary equipment, uplink and downlink signals as expected, already got a command in.
Fault Prot - Quicklook, no abnormal responses to the burn, out of go-fast mode.
Nominal termination to the MOI nominal block.






http://mars.jpl.nasa.gov/mro/realtime/mro-doppler_lg.html
Interesting Pre MOI PDF Presentation
http://www.hq.nasa.gov/office/codeq/smadir/hq06/landano.pdf



11th March 0030 Press Conf Update

Usual superlatives from senior management that don't tell us anything.

Jim Graff acknowledged help from NOAA w.r.t. Solar Weather, and the DSN's outstanding job.
Howard Eisan : MRO is safe, stable, on earth point, transmitting at 550kbps. We've earned the 'RO' of MRO. Dippled less than 10% into the batteries, commanded velocity change 2237.6 mph, overshot by 0.4mph, during the burn we underperformed by 2%, burned by 33 seconds longer to make up the difference. First hr of Nav data - orbit 35.5 hrs (predict 35.6) 264 x 28,000 mile orbit.
Rich Zurek : 2 of our 8 investigations were ones lost with MCO, one of those was also lost with Mars Observer. This completes replacement of all the Mars Observer instrumentation. We're going to knock your socks off - it's a good day.

Sally from TPS : Break for 2 weeks, what are you going to be doing (are you going to be celebrating for two weeks) - JG - stand down for w'end for a rest. Then prepare for aerobraking. ORT for Aerobraking, reconfig spacecraft for aerobraking, and some software patches to send up (9 uploaded to date, a few more to go). One other thing - we will take some early images - engineering images not science quality, make sure they work properly, processing that data on the ground to make sure the processing centres can extract the images from the data.

Sally asked when that science will start. RZ mentioned the use of aerobraking (lowest altitude is 60 miles) to understand structure of atmosphere. Sally asked if aerobraking is hard every orbit. RZ said that most of the closest approaches will be over the south pole. They dont expect big dust storms.

That's all the questions- again, kudos to Sally for asking them something. Unarguably the most important moment in Mars exploration since MER landing and potentially more important than anything between then and MSL landing scientifically, and in terms of infrastructure on orbit - $700M's worth of project - and that's three conferences where Sally was almost the only person to ask any questions. Either JPL PAO has furning the media with every single piece of information they could want before the event, or the media seem to be barely taking note of the mission because it's not as sexy as a landing ( there were plenty of spare seats in the V.K. auditorium, at Spirit's landing conf, you couldnt swing a cat in there ). Under-representation of mission rant over.

Doug

Attached File(s)

 doppler_1.mov ( 119.34K ) Number of downloads: 404

 

[Guest_BruceMoomaw_*]

I imagine the single biggest sigh of relief came from Dennis McCleese. He must feel like Charlie Brown after Lucy finally allowed him to kick the football.

[djellison]

Maybe there are 6 orbiters

But not 'operating' at mars.

Doug

[jmknapp]

One of the trajectory guys said on NASA TV yesterday that with the fuel they saved by not needing any course adjustments since last November they potentially extended the life of MRO by 9 months. They sure earned their pay (and maybe a bonus) for that accomplishment.

[deglr6328]

Burn time 1641 seconds vs 1606 expected. 1000.48 m/s compared to 1000.36m/s expected.

So burn performance 97.87% of nominal, but actual Delta V 100.012% of predicted.

i.e. yes - the burn was a little under the mark, but the onboard sequence saw this, worked off the Delta V, and terminated the burn according to the accumulated Delta V hitting the right mark.

Doug

This is really most fantastic. We are talking about a target change in velocity of over 2,200 mph and it was achieved to within a few inches per second!! that's some good engineering.

[RNeuhaus]

Rodolfo:

There may be some Soviet vehicles still there, too. I doubt if they've all decayed so soon!

Bob Shaw

All Soviet (not very sure, need more time to search about this to confirm), one Japan and all Mariner for Mars except one has flown by Mars and they are orbiting around the Sun. So now, there is 7 orbiting around Mars, three are inoperative (Vikings I, II and Mariner 9). In resume, up to know there is 65 % of MOI to Mars with success.

Rodolfo

[ljk4-1]

All Soviet (not very sure, need more time to search about this to confirm), one Japan and all Mariner for Mars except one has flown by Mars and they are orbiting around the Sun. So now, there is 7 orbiting around Mars, three are inoperative (Vikings I, II and Mariner 9). In resume, up to know there is 65 % of MOI to Mars with success.

Rodolfo

I know that Mariner 9 and the Vikings were placed in orbits around
Mars in part to stay up for at least 50 years to "remove" any micro-
organisms that might have survived on them.

The Soviet probes Mars 2, 3, and 5 were successful orbiters, but I
do not know if they are still in space or how well they were sterilized.

Phobos 2 did get into Mars orbit in 1989, but I read that it might
eventually crash into the moon it is named after. Anyone have an
orbital plot on this?

Mars 4 was supposed to orbit the Red Planet, but its braking rockets
failed. Mars 1, Zond 2, and Mars 6 and 7 were all flybys (the latter
two and possibly three with accompanying landers).

[Guest_AlexBlackwell_*]

I imagine the single biggest sigh of relief came from Dennis McCleese.

Who's that? Dan McCleese's son/nephew/uncle/grandfather?

[The Messenger]

Who's that? Dan McCleese's son/nephew/uncle/grandfather?

John Cleese's Irish cousin

The 2% lag in performance - Any clues as to why? TCM-2 was much more precise, or was there a performance correction during the burn as well?

[Circum]

The 2% lag in performance - Any clues as to why? TCM-2 was much more precise, or was there a performance correction during the burn as well?
[/quote]

During the NASA TV coverage, I believe I heard something about chamber pressures being slightly low, which was not a complete surprise since certain temperatures were also slightly low.

I didn't hear any explanation or further details about the low temperatures, but somehow I doubt it was 'new physics'. . . .

Also, could someone with more propulsion knowledge step in, I somehow have the impression that MOI was the first time they had pressurized the chamber, so did the TCMs use a different mode or different engines or something?

[djellison]

The engine's just didnt quite provide as much punch as they expected during MOI, so the onboard software commanded the shutdown slightly later than they expected it to happen.

If you're only doing a tiny nudge, a few m/sec - then it would be hard to notice a 2% shortfall in the expected performance ( I don't know if TCM 1 was done using a delta-V accumulation or a timer but either way, it'd be a tiny error on a small burn ) - whereas with a burn thats more than a thousand seconds then it's going to be a lot more obvious.

Doug

[ugordan]

Also, could someone with more propulsion knowledge step in, I somehow have the impression that MOI was the first time they had pressurized the chamber, so did the TCMs use a different mode or different engines or something?

I think this was the first and only time the propellant tanks were pressurized. The TCMs probably were run at default tank pressure, while before the MOI burn pyro-valves were opened to allow helium into the propellant tanks for pressurization. As Doug noted, the temperatures were slightly colder resulting in a somewhat lower prop tank pressure and, consequently, lower thrust.
The engines used on space probes are always pressure driven and the pressure of propellant tanks makes for quite a difference in thrust.
As a comparison, engines used on launch vehicles are turbopump driven and are vastly more complicated/expensive, but have the advantage of tanks not being required to handle great pressures (meaning they can be made light).

[mcaplinger]

did the TCMs use a different mode or different engines or something?

Yes. TCMs were done with the 22N thrusters alone, while MOI also used the 170N thrusters for the first time (press kit, page 36.)

[Circum]

Thanks for all the info dje, ugor, and mcap.

[Bob Shaw]

I know that Mariner 9 and the Vikings were placed in orbits around
Mars in part to stay up for at least 50 years to "remove" any micro-
organisms that might have survived on them.

The Soviet probes Mars 2, 3, and 5 were successful orbiters, but I
do not know if they are still in space or how well they were sterilized.

Phobos 2 did get into Mars orbit in 1989, but I read that it might
eventually crash into the moon it is named after. Anyone have an
orbital plot on this?

Mars 4 was supposed to orbit the Red Planet, but its braking rockets
failed. Mars 1, Zond 2, and Mars 6 and 7 were all flybys (the latter
two and possibly three with accompanying landers).

Yes; I think Rodolfo has missed the four Soviet vehicles placed in orbit around Mars, though whether they still are is another issue.

Bob Shaw

[ToSeek]

Yes. TCMs were done with the 22N thrusters alone, while MOI also used the 170N thrusters for the first time (press kit, page 36.)

That's not quite true. TCM 1 was used to check out the main engines. See this press release.