October 19, 2014 Mars flies through comet tail.. Big explosion recorded ? Video

originally posted by: roadgravel

Satellites: they are designed to be looking "down" at Mars, not up and out from Mars

There isn't really an up / down in space. Just turn the satellite.

Given the amount of time NASA is said to spend covering up it's work, I am surprised anything new can even happen. I figure they are still clearing the back log from 1995 to 2005.

I'm afraid you do not "just turn" a satellite.

It's not a car.

If it's sensor and camera arrays are fixed on a certain point of that body, it will be indeed pointed DOWN towards the planet it is orbiting if it's main purpose in life is to photograph the surface of a planet that is BELOW it.

You are right, there is no "Up" or "Down" in space. However, those words are still used to describe orientation and position of spacecraft and probes.

If the arrays are not on a movable platform (IE one that can move about), then you have to realign the orientation of the entire satellite to take images other than the planet.
In order to do that, if it does not have built in gyros to do so, would need some sort of monopropellent system that fires short bursts. That uses fuel that otherwise may be used to keep said satellite in orbit or adjust it's altitude.

I know a lot of people think "well just turn or move the satellite" but unless it was designed for it, that can be harder to do than you'd think. If the main mission of a satellite is to have it's "eyes" pointed to the planet, adding things to move it around to look out into space adds cost and mass to the satellite that can be hard to justify if the primary purpose of the satellite isn't to do that.

We do have satellites specifically designed for that, like Hubble. But a NOAA weather satellite won't be.

a reply to: eriktheawful

Sending a spacecraft to mars that can't be turned. Makes perfect sense.

originally posted by: roadgravel
a reply to: eriktheawful

Sending a spacecraft to mars that can't be turned. Makes perfect sense.

I think eriktheawful was speaking in general terms. MRO can, and was indeed, turned to observe the comet. LRO can turn itself as well, to get oblique views of the Moon. Cassini spacecraft regularly turns to photograph Saturn and its numerous moons and rings.

We have pictures from Mars orbiters, check for links earlier in this thread.

Here's an interesting tidbit about this comet (courtesy of Leonid Elenin):

The comet's gravitational interaction with Mars means that its otherwise open trajectory, which meant that it would leave the Solar System forever, was reduced to a closed trajectory, which means it will return in 17 million years. Mars "captured" this comet and made it Solar System's own.