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Photo shows Mars rover descent (bbc.co.uk)
187 points by zoowar on Aug 6, 2012 | hide | past | web | favorite | 59 comments

It looks like they had the coordinates of the decent path of Curiosity, knew where to point the camera, took a large picture from the HiRISE camera on the Mars Reconnaissance Orbiter (MRO) like they did with Phoenix [1] and then when that picture hit human eyes NASA cropped it. That being said, if they have multiple HiRISE images of the decent[2] I think that would make one amazing film. Anyone know the FPS of HiRISE? [1]http://blogs.nature.com/news/files/2012/08/PhoenixHiRise.jpg [2]http://news.bbcimg.co.uk/media/images/62081000/jpg/_62081182...

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.


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.

Every single time I look at images captured by the rovers on Mars, it throws a wave of tingles through my spine.

The technology and brain power to achieve this picture, the landing, engineering and the science to come is so mind blowing to me that I almost feel drained!

Such a massive amount of awesomeness.

is there one without the white box?

I've been looking for one as well. It appears as though they're still working on releasing more of the images.

The HiRISE news release[1] now contains a (currently broken) link[2] to a 540MB non-map projected "descent long view." I imagine this is the complete scan that HiRISE took of the image, and that there is distortion due to the CCD layout in the satellite (hence non-map projected). But that's purely a guess.

They say:

  Descent long view[2] (Note: this file is over 540MB. It is non-map projected
  but rotated so that north is approximately up. This file is not annotated, 
  but MSL is in the mid-to-lower right-hand side. The CCDs do not match well at 
  their edges due to the unique image geometry; geometrically-corrected images 
  would be available in a few days.)
1: http://hirise.lpl.arizona.edu/releases/msl-descent.php

2: http://hirise.lpl.arizona.edu/images/2012/details/cut/ESP_02... (WARNING: 540MB TIFF, but link is broken at time of posting)

Your 2nd link works now and the image is without the white box! Here is a 1600x1200 version: http://i.imgur.com/708I5.jpg

There is a seam just to the left of the package, which is why NASA presented the image with the object off-center, and why I cropped it that way as well.

Would make a great desktop

In the meantime, you can cut one from this monster image


NASA is a wonder of our modern age. If we're going to have a planned economy (and we are), let's do it through science, technology and knowledge rather than military power.

700B for DOD, versus 8B NASA. 87x difference. If NASA would have 87x more money, by now we would have a Martian base and most likely missions where civilians could buy a ticket and fly there for a honeymoon.

TSA gets more money than NASA!

(and TSA is just a tiny part of "homeland security (theater)" )

To be fair, a lot of money that went into ICBM research ended up being applied by NASA.

But I agree with you. If only we could convince the five top military spenders to cut back just a little, we'd be terraforming Mars and Venus by the end of the week. ;-)

But at the same time the USA spends more money on space programs than all other countries combined.

It could simply mean that running space programs in the USA is far more costly than in other countries. Someone did say that NASA of the recent age is less about research and more about massive employment.

I would say, the price difference adjusted budget of NASA is also much bigger than that of any other nation. Do you see the Russians walking on the moon or driving nuclear cars on Mars?

Guess this is because no other country has that level of expertise of space program like US.

Your causality presumption may be reversed.

Yeah funny how much we spend on stuff that blows up (or never does because it's never used and we have to spend even more billions dismantling them).

Interesting, what makes you so sure we are going to become a planned economy when it was partially the governments corruption in the first place that helped lead to this mess. 

I know you mean USA. I wonder if the USA would force my country (Australia) to follow suit to? Hard to imagine.

Also isn't China meant to be growing at a unstable rate and is now ready for its own property market collapse. And isn't China the only real example of a working centrally planned economy?

I'm just really interested how you are so sure we are heading towards a planned economy as a system. 

I don't see a case to make the funding of NASA greater. What has the recent Dragon (by SpaceX) experiment proved is that NASA usually does things in a more expensive way than private parties. It would more efficient to outsource most of this research to do more with the same budget.

This to me feels really sci-fi since "we sent a rover to mars and another thing we already had hanging around took a picture of it." That feels pretty neat.

Anyone has any background info on that picture? How did the MRO lock on the descending rover?

Did NASA feed it the correct coordinates beforehand, or it had to somehow autonomously acquire the rover? I suspect the later is possible, as there might be radio contact available in that stage of the reentry, but I really have no idea on how it was actually accomplished.

Here is a link to a Nature blog with some info from Alfred McEwen, the PI on HiRISE:


My impression is that they only got the opportunity for one shot with the HiRISE camera, but that they were going for a view of the sky-crane in action. Did that turn out not to be possible? Do they have a picture of the sky-crane from one of the lower-resolution cameras in orbit?

The coordination of all this just blows my mind.

it says: "nuclear battery". it looks small. can someone point me to some more details? Obviously if they decided its fine to shoot this thing into the space (go through Earth atmosphere) - it should mean that there was no environmental danger for this thing to go bad?

Nuclear batteries are unlike what we normally think of as "nuclear reactors". They both use heat, but nuclear batteries do not bring the fuel to criticality (in other words, no chain reaction). This limits their power output obviously, but they are pretty damn reliable in return.

The one in Curiosity seems to have 5kg of Plutonium 238. I don't know what kind of containment it has to protect it during launch, but I assume it is fairly substantial. Nuclear batteries are not something NASA is new to, they have used them many times before, including in the Voyager probes.

Interestingly, nuclear reactors have been put into space too, by both the US and the Soviets. There have been incidents but nothing that I would really call a disaster. http://en.wikipedia.org/wiki/RORSAT

It's an RTG, it uses the heat created by decay of radioactive isotopes to drive a thermocouple. These things have been designed to be incredibly safe, capable of surviving an explosion of their launch vehicle and remaining intact, for example. But even should their protective capsule be breached the radioactive material is in a ceramic (oxidized) form in spheres. If you cracked open an RTG and threw the insides into a very hot fire nothing would happen, you could just come by and collect the intact ceramic spheres after they'd cooled.

So ignoring the safety issues, would there be enough radioactive isotopes on Earth for every house to have it's own RTG? Imagine unlimited energy, and heat your home with the waste heat?

What's wrong with the economies of scale of larger nuclear plants? I'm asking curiously, I don't understand the fascination with home energy sources.

Radioactive decay is a small energy source compared to fission. Look at the binding energies [1]: the energy accessible by fissioning heavy elements is about 200 MeV -- 1 MeV per nucleon. Radioactive decays are two orders of magnitude less, or smaller.

Pu-238 is one of the nicest ones because it is "clean" -- emitting only alpha radiation, which is easy to shield. You can transmute on the order of 1 atom of it per 100 fission events [2]. A fission event is 200 MeV; a Pu-238 decay is 5.6 MeV. So at steady state, you can support less than 1/3,000th as much Pu-238 power as you can fission power. If you have a Pu-238 source, you also have a vastly larger nuclear fission power source, so why not just use that?

More broadly, it's not a likely idea on physics, even if you accept all radioisotopes (difficult-to-shield gamma emitters) and not just "nice" ones. The high-Z radioactive decay chains end quickly at the element lead [3], so only release a fraction of the energy that is accessible by fission. (Look back to the binding energy curve [1]). And many of these decays are unusably, geologically slow. The naturally-occurring radioisotopes have half lives of >10^8 years (otherwise they wouldn't exist anymore -- they were created in ancient history in supernovae). And trying to transmute them doesn't improve much -- i.e. in a fission reactor, the most common [4] high-Z product is Pu-239 (half life >10^4 years), whose next decay is to U-235 (half life >10^8 years). Others are similar. So I don't see any way forwards.

[1] http://en.wikipedia.org/wiki/File:Binding_energy_curve_-_com...

[2] Through the several processes which create Np-237 from uranium -- a relatively rare process [4]. Np-237 can be isolated and transmuted to Pu-238 separately through neutron irradiation

[3] http://en.wikipedia.org/wiki/File:Radioactive_decay_chains_d...

[4] Small table here: http://en.wikipedia.org/wiki/Minor_actinide

Probably not. The problem with isotopes needed for things like this is that they tend to have short half-lives (short half-lives = high decay rate = lots of heat generated), which means they pretty much don't exist naturally at all. So they will need to be produced artificially as fission fragments or through neutron irradiation of other isotopes. It's easy enough to produce large quantities of "hot" isotopes in a fission reactor which could be used for RTGs (ignoring safety) but the problem there is that if you're operating a nuclear reactor anyway why not use the heat production from the isotopes to produce energy there instead of going the roundabout, and unsafe, route of packaging things up in RTGs?

There's also the thermocouples, which also wear out and are made of pretty expensive materials themselves.

However, it is likely that a "home" device could be made simpler/less expensive.

Couldn't they use a sterling engine as well? That would be a bit more maintainable I would think?

You're also ignoring the political/emotive aspect.

People don't like things called 'nuclear'.

There are certainly some places that would probably be more accepting of it than average. http://en.wikipedia.org/wiki/File:Soviet_RTG.jpg ;)

Those are 10 watt Sr90 RTGs, sitting around. The used to use them for lighthouses.

Well... as much as I like RTGs and even fission reactors there is a little bit of justification there. Of necessity an RTG pretty much needs to contain hazardous radioisotopes. Putting that into the hands of every joe blow is probably not the best idea at present.

Just cribbing from Wiki, the generator contains 11 pounds of Pu-238 and produces ~150W of electricity from ~2000W of heat. It's hard to put an exact price on it, but it's definitely in the $millions per kg.

It's theoretically feasible, but the cost would be, ah, prohibitive.

Plutonium 238 would be your best bet for such devices, if only because it's halflife is 87.7 years. Strontium 90 might also work, with a halflife of 28.8 years.

However plutonium would not be easy to put in every house since you have to make it in nuclear reactors. You get about half a kilowatt per kilogram of it, I don't think production of it could scale that high.

Strontium is naturally occurring and relatively common. Sr 90 is a trace isotope though. Off the top of my head I would suspect you would be facing similar challenges that separation of Uranium isotopes face.

Sr-90 is not naturally occurring because of its short half-life. Any Sr-90 found today is either from weapons testing or made in a reactor.

I thought there was a ban on radioactive materials being launched by NASA but I couldn't find anything about it, does anyone know any more?

At least three unrelated "nuclear" things are involved:

* Radioisotope power sources (like this, Cassini, New Horizons, etc.)

* Critical fission reactors (popular in the early space race before solar PV, still the best option for high-power deep-space missions like (cancelled) Jupiter Icy Moons Orbiter/Project Prometheus)

* Nuclear pulse propulsion -- setting off nuclear weapons, riding the shockwaves (e.g. Project Orion)

Pulse prolusion is banned, quite pointlessly, under the Partial Test Ban Treaty of 1963. (Note it extends not only to atmospheric explosions, but ones in deep space). The others aren't. Contained, critical nuclear reactions are legal -- NASA chose a nuclear reactor a few years ago for the Jupiter Icy Moons Orbiter, before they cancelled it. And no one cares about radioisotope sources except confused hippies.


Obscure history: a running Soviet nuclear reactor crashed from space into the Canadian wilderness in 1977. In case anyone's curious of the consequences.


You may be thinking of Cassini; it is powered by an RTG and flew back by the Earth for part of its gravity assist, which caused some controversy about if it somehow went off course and re-entered Earth's atmosphere.

More info here: http://www.motherjones.com/politics/1997/09/cassini-controve...

You might be thinking of the Partial Nuclear Test Ban which banned nuclear detonations in space (ending Project Orion).

It uses a radioisotope thermoelectric generator (RTG). Many spacecraft use them. The Apollo 13 RTG is currently at rest on the ocean floor.


NASA is just rocking this mission. Very impressed.

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