According to the press release, they will be monitoring live on NASA TV. 109 km is cutting it a little close to Mar's fickle atmosphere - I think this is near the final projected path of the Mars Climate Orbiter, but it actually went in somewhere between 95-80 km...

Rodilfo:

Not at all. Relatively speaking, the upper atmosphere of Mars extends *further* from the planet than does that of the Earth, and the pressure drops more slowly. So 109 km is well within the (very thin) upper atmosphere. Mars is particularly good for aerobraking, having a thin but extensive atmosphere which should be more forgiving than our own. But, after MCO and Mars Observer, there will be a certain tension in the (rarefied) air!.

Fingers, and all other appendages should be tightly crossed, chickens should be broken down into component parts, and any spare virgins kept neatly wrapped but ready for sacrifice - it's scawwwwwwy!

Bob Shaw

Of course - the reason for having such a low targetting point is because a periapsis that low invokes a fast orbital velocity - thus the ammount of engine braking required is less. If they targetted at say, 1500km, the orbital velocity at that altitude would be much slower so requiring much more delta V.

One day - I hope they'll be brave enough for Aero-capture at Mars. It's a very thin line to tred - +/- 10km will give you a bad day one way or the other, but they're getting to the point where it's possible, I'm sure.


Looking at this -
http://space.jpl.nasa.gov/cgi-bin/wspace?t...orbs=1&showsc=1

Goldstone will be the primary, with Madrid just setting.

Doug

IIRC, with MER, some secondary facilities (Stanford) were also listening. Wonder if they might do the same with MRO.

Stanford was listening to MER because MER was also transmitting with its UHF antenna (to MGS), for which Stanford have a good facility, and indeed they caught Spirit, but not Opportunity as I understand it. No such transmission is planned for MRO as I understand it - just X-Band on the LGA which will be for the DSN to grab alone.

Doug

I think there's some confusion. The aimpoint altitude at MOI is 400 km, not anything lower. After MCO, they're unlikely to try anything much lower.

Ahh - someone mis-quoted the press pdf previously then - it seemed a bit low to me

Doug

Doug:

I was wondering, too - much lower than MGS!

Let's hope it *doesn't* go low...

Bob Shaw

I am thinking about why any of three present Mars Orbiters, ODY, MGS and MEX aren't capable as a relay of any signal from a new member MRO to Earth and viceversa? The rovers might be the witnesers with their PANCAM. Not sure about its proper localization at the MOI critical moments.


Maybe, the space portal: spaceflightnow is confused. Below is the extract:

To take full advantage of atmospheric braking, the low point of the orbit will be carefully reduced to around 62 miles (100 km). It will be raised, or "walked out," later, with the ultimate goal being a roughly circular orbit with a high point of at most 199 miles (320 km) and a low point as close as 158 miles (254 km) to the surface.

http://www.spaceflightnow.com/mars/mro/060224moipreview.html

Rodolfo

You're quoting the altitude during aerobraking, not the altitude at MOI, which is much higher.

Originally, a lower final orbit (150km) was planned, but they raised it. I am confused enough now that I don't know if they raised it to 300 or 400 km. From Neuhaus' earlier post on this thread:

"Spacecraft Configurations:

During aerobraking, the solar panels have a special role to play. As the spacecraft skims through the upper layers of the martian atmosphere, the large, flat panels act a little like parachutes to slow the spacecraft down and reduce the size of its orbit.

The friction from the atmosphere passing over the spacecraft during aerobraking will heat it up, with the solar arrays heating up most of all. The solar arrays have to be designed to withstand temperatures of almost 200 Celsius (almost 400 degrees Fahrenheit!).

MRO will get very hot, up to 200 degree of centigrades at the perigee passing."

This is consistent with an orbital insertion altitude of 109kms, and a final, rounded orbit of 300-400 km. I think the lowest 'safe' insertion altitude for MCO was 85km, so 109kms may be a little iffy...

The altitude at MOI has little to do with either the aerobraking altitude or the final mapping orbit altitude. These altitudes are:

400 km at MOI (press kit, page 27)
~100 km during aeropass (press kit, page 30)
320 km x 255 km in final mapping (press kit, page 28)

What's so confusing?

The way some websites have reported it is all screwey - even the normally reliable ones.

Doug

Nothing...if you scroll beyond the 'Other Missions' in the Press release, thanks. An insertion @ 400km is much, much safer than the 109km figure quoted above. That is chillingly close to the Climate Orbiter's planned trajectory.

I don't know if it's been mentioned here or not but SHARAD has a dedicated web site, which has some interesting documentation.