India's Mars probe (MOM), Development, launch, and cruise to Mars Options

[Doug M.]

So far so good. The liquid fueled fourth stage has ignited. Hopefully everything works...

As of 3 AM EST Tuesday, all systems are nominal. They're going to do their first orbital adjustment later today. Fingers crossed!


Doug M.

[tolis]

MOM Martian orbit parameters:

MOI Epoch: 24-09-2014, 02:34
Periapsis: 365.3 km
Apoapsis: 80000 km
Inclination: 150.0°
AOP: 203.5°
RAAN: 61.4°
Period: 76.72 hr
Sun Elevation: 6.8°

http://www.isro.org/pslv-c25/pdf/pslv-c25-brochure.pdf

On the subject of satellite flybys, from the above elements it seems that the orbit crosses the Martian equatorial plane
- where the satellites orbit - at distances from Mars' center of 44,400 km (going south to north) and 3,900 km (going north to south).
So, at least initially the spacecraft can not come particularly close to either of the moons. Later, as the orbit orientation changes due to the action
of the Sun's gravity and Mars' non-spherical shape, encounters with either moon will become possible. Of course, there is no guarantee that the
spacecraft will still be alive then.

[walfy]

Looks like India's MOM probe can be tracked here: http://www.n2yo.com/?s=39370

Also this link with more info: http://www.n2yo.com/satellite/?s=39370

As it nears its apogee of 28,746.0 km high, there's some projected retrograde motion for it's relative path on Earth's surface, for slowing way down up there, I'm assuming, and Earth's spin overtaking it's orbital speed.



Is it just coincidental that it reached apogee here just as its path reached it's northernmost part on Earth? It can reach apogee at any point along its track on Earth, and does not have to coincide with it's northern or southernmost path along the Earth, right? Probably a dumb question.

[Explorer1]

Being in direct contact with India is probably a boon to operations; remaining in orbit to do checkouts/adjustments prior to the Mars trip has more benefits than just a smaller rocket, in terms of signal delay, familiar environment, etc.
Why doesn't this happened more often? Launch a probe into parking orbit when it's assembled, do checkouts and instrument commissioning at a leisurely pace, and burn with your final stage to interplanetary when the appropriate window opens up.

[Paolo]

2013 is probably too early, 2016 or 2018 may be more realistic.

I love to be proven wrong sometimes! congratulations to all involved!

[Doug M.]

Why doesn't this happened more often? Launch a probe into parking orbit when it's assembled, do checkouts and instrument commissioning at a leisurely pace, and burn with your final stage to interplanetary when the appropriate window opens up.

I don't know the answer, but two thoughts come immediately to mind. One, checkouts and instrument commissioning don't seem to take all that long -- a few days, at most a week. Two, Earth orbit may not be a good place for deep-space probes to spend lots of time; there are the radiation belts, at perigee they're encountering Earth's exosphere, and so forth. Earth satellites can survive for decades, but they're designed for it. It's possible that a week in Earth orbit might strip several weeks of the potential lifespan of a Mars orbiter.


Doug M.

[bobik]

"The second and third such operations would be made tomorrow and on Saturday to raise the mission apogee to 40,000 km and 71,650 km respectively. The fourth and fifth operations would be performed to raise the apogee of 1,00,000 km and 1,92,000 km on November 11 and 16 respectively. After the successful completion of these operations, the mission is expected to take on the “crucial event” of the trans-Mars injection around 12.42 am on December 1."

http://www.firstpost.com/india/closer-to-m...rce=ref_article

[robspace54]

Glad that the ISRO launch of MOM has been successful. I have some info on the s/c gleaned from the Internet.

MOM is based on a modifieed I-1000 satellite bus, first used in the METSAT-1 weather satellite of 2002, which was later renamed Kalpana-1 to honor the late Indian-Amercian astronaut Kalpana Chawla, who died abord space shuttle Columbia.


Rob

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[mcaplinger]

Why doesn't this happened more often? Launch a probe into parking orbit when it's assembled, do checkouts and instrument commissioning at a leisurely pace...

Most interplanetary spacecraft are launched into a parking orbit, but they only stay in it for a few minutes before injection. AFAIK there are no delta V savings for the MOM mission profile, it's mostly because the spacecraft engine doesn't have enough thrust to do the injection in one burn.

As for checkout, there's plenty of time to do it in cruise, and it's not like you can go up and fix it if you stay in Earth orbit anyway.

[djellison]

Moreover LEO is a poor place to checkout because you have rapid day/night cycles, and any one DSN pass would only be a few 10's of minutes, rather than a more typical 8 hours. And it's quite possible that LEO on an LGA is a poorer downlink than cruise on an HGA.

[Explorer1]

http://www.planetary.org/blogs/emily-lakda...er-mission.html
Looks like burn four was not completed as planned. They're going to make up the shortfall tomorrow.
This method seems pretty flexible...

[pospa]

Detail issue explanation in today's ISRO press release.

[pospa]

According to info here MOM still has 4 kg fuel reserve today thanks to precise orbit insertion after the launch.

[mcaplinger]

http://www.planetary.org/blogs/emily-lakda...ion-update.html

A schematic of the propulsion system plumbing would be needed to completely make sense of this.

Normally, redundant latch valves are in parallel so that either one or the other can control flow to the engine (and there are normally-open pyro valves in the lines that can shut one leg down if its valve sticks open.) I haven't heard of needing or wanting both open since if they behaved differently they wouldn't be truly redundant (a crude form of throttling?). Perhaps in trying this there was some flow-splitting problem and the flow rates weren't what they wanted. At any rate it seems a bit odd -- hopefully this afternoon's burn will go well.

[Explorer1]

And it did go well! Apogee now 118, 642 kilometers.

http://isro.org/mars/updates.aspx