If I understand and remember it correctly, HiRISE doesn't have an FPS in the traditional sense. It's best to think of the detector as a one-dimensional array of pixels. The motion of the satellite in its orbit then sweeps this array over the ground, allowing two-dimensional images to be made - one of the dimensions is time, but when something is moving, time becomes a spatial dimension.

Good point. It's called "pushbroom scanning" and is used on lots of remote sensing satellites.

http://hirise.seti.org/epo/hirise_lesson1.htm

On a related note, the "forward looking" in FLIR refers to the fact that FLIR cameras are not sideways tracking, or "pushbroom". The name doesn't actually have anything to do with where the FLIR camera is mounted.

Interesting, its like "scanning" not a shutter "clicking". That being said it was much more likely given the MRO's orbit that it would be able to scan Mars and have Curiosity in that scan path. You can even correlate the angle of the photo to the location of the MRO: http://www.nasa.gov/images/content/672880main_martin_mur-1-4...

To be fair, most modern (CMOS) digital cameras work like that too, it's called a rolling shutter. The scanning speed is the cause of that wobbly effect you see on videos made with mobile phones.

True, but if you can do 1m fps on earth[1] and the MRO travels at a speed of 133,879.68 inches/second then you could take 7.4693934 pictures per inch even if you had a rolling "scanning" shutter. I know that would be way to much data for them to process, but for the 172 seconds from parachute deployment to touchdown you could have one amazing high speed film.

I am sure NASA can fund a high speed camera for MRO... or do we need to crowdfund that one as well... [1] http://www.youtube.com/watch?v=QfDoQwIAaXg

cameras with a focal-plane shutter also "scan", more or less.

In the article it says that they basically took the only picture they could. A second later or sooner and they'd have seen a landscape only.

Looks like there was quite a lot of time for taking pictures[1], 172 second to be exact between parachute deployment and touchdown.

[1] http://www.nasa.gov/images/content/672880main_martin_mur-1-4...

Not really. The MRO is moving fast and at a relatively low orbit.

"If HiRISE took the image one second before or one second after, we probably would be looking at an empty Martian landscape," said Sarah Milkovich, HiRISE investigation scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "When you consider that we have been working on this sequence since March and had to upload commands to the spacecraft about 72 hours prior to the image being taken, you begin to realize how challenging this picture was to obtain."[1]

[1]: http://www.nasa.gov/mission_pages/msl/news/msl20120806b.html

Since HiRISE appears to be more of a "scanner" than an instant-in-time snapshot, I was curious why they had to pick a specific second to take a "photo", instead of just scanning across the likely region. It seems that the answer is on-satellite memory: since the images can't be transmitted anywhere near real-time, they have to fit into the 3.5 GiB local storage. That limits the 20,000-pixel wide "scanner" to recording 126,000 pixels along its trajectory before running out of memory, with a long pause for transmission before it can start recording again.

Well it's not that simple because you have to take under consideration that MRO also moves. So basically you have two objects moving at some thousand kilometers per hour in different trajectories and you have an open window of a few seconds to take the picture.

Ok, who wants to play a game? Where was MRO in this picture: http://www.nasa.gov/images/content/672880main_martin_mur-1-4... when it took this picture: http://news.bbcimg.co.uk/media/images/62081000/jpg/_62081182... Height of the parachute is 50m while the width is 16m. GO!

The article says 340km away.