A nice play by play of the landing culled from the YouTube comments (attributed to "flyhighj65"):
0:15 - Obviously heat shield separation
~0:25 to 0:30 - Back shell separation and powered flight
0:31 to 0:38 - The rover banks to move towards the
upper left corner of the screen (camera looks opposite
direction of motion)
0:38 to 0:41 - The rover banks the opposite direction
and stops its horizontal motion to drop straight down
~0:47 - Skycrane maneuver begins
0:48 - Wheels deploy (top left corner of screen)
Touchdown is shortly after the video ends
Just as aside, it's amazing that people spend significant effort making intelligent remarks on YouTube (such as the above) only to see it get buried in a sea of inane comments. (It's already at 1,380 comments for this Mars video.)
FYI, it's sped up because they only take 4-5 frame per seconds. The heat shield separation is at +278s (278 seconds after atmospheric entry) and the touchdown is at +416s. That's a difference of 138 seconds, which in the video takes about 38 sec (0:15 - 0:53), so the play-back speed up is about a factor of 3.6.
I know that a HD version will eventually make its way from Mars to Earth, but I have read in a couple of places that the Descent Imager only operates at 5 fps. That could have been a mis-statement though.
I (or perhaps what I was reading) may have had the descent cam's stats confused with the high-quality mast cam, which won't be deployed until next week. Still exciting, though.
There was a discussion on Reddit about the instrumentation on MER - specifically that every concievable scientific instrument is on the rover, but no HD video camera or microphone. Apparently, the reasoning behind this is that these things are scientifically uninteresting.
But imagine the PR benefit of getting full-motion video and audio from Mars. Even if we don't learn anything interesting from this, the media effect would have been tremendous. People could finally see video and sound on the evening news, in HD...almost like being on Mars. It's too bad the MER team wasn't willing to do this, seems like it would have been a relatively cheap addition to the project.
But don't get me wrong, this is still very, very cool.
If i remember correctly, rover has a 720p video camera that records 10fps. And considering the speed of the movement of camera or robotic arm, any higher fps would have been redundant. I don't know about microphone though. Plus there is a novelty factor. The first full HD 3d 60fps video with 6 channel sound will probably be the most popular YouTube video of the year. But that's it, no one would watch the second video because all of it would be same. largely because rovers travels very slowly and also because it's just rocks and dust, just like any desert here on earth. The cost of the added weight and volume of more capable camera for just one popular video is not justified IMO.
I don't understand why bandwidth needs to be such a problem.
Invest in a ring of small satellites in mars orbit, have them broadcast to earth satellites using line of sight transmitters for whatever mars satellite is facing the earth. Once you build such a system you can reuse it for each future mars/deep space mission.
Use open standards so other nations can expand the network.
How much would it cost to cover the inner core of the solar system with 100 Mbit/s bandwidth using a mesh network of satellites?
That's an interesting take. But HD video would be slower to transfer from Mars to Earth as well, wouldn't it? Although it might not matter since it's not like we have to watch everything live 24/7.
HD video would also be competing with science data for both storage and transfer time.
If you read the blog of the MER driver at http://marsandme.blogspot.com/ you can see this tension already play out sometimes, both in scheduling nice panoramic pictures and managing the data storage until a transfer window opens. Science normally wins. :)
One of the surprising thing to me about the internet response to curiosity is that I've seen many commenters who seem to assume we can stream live HD video from Mars; some expected it to somehow manage this feat even while landing. But really, Curiosity talks directly to Earth at only 32kbps, and has around 16 minutes per day of high-bandwidth (2 mbps or less) communication with the Mars orbiters.
I can't wait to see the higher definition videos. Also - there was quite a bit of dust being blown around there.
It will be interesting to see if there is any followup as to whether the SkyCrane maneuver is really required, or, whether in the future, we can land directly on rocket engines. Particularly with the Plutonium power supply - no need to be concerned about solar cells getting covered in dust.
Also - I seem to recall that there can be fairly significant dust storms on mars anyways - so it's not as though landing without rocket engines means that the Rover will be immune from getting struck by pebbles/rockets/dust.
A couple of people from the JPL team talked about why they used the sky crane rather than other methods and they mentioned that the amount of dust caused by using rockets all the way down would cause issues for the rover. So it seems like some dust is ok but too much would cause enough problems that the sky crane is worth it.
Might they want to minimise interference with the layers of dust/dirt on the ground, where possible? Probably not - maybe that's akin to explorers worrying about longboats pushing into the sand when they reached a beach...
They plan on driving a significant distance, so I don't think they're too worried about contamination of the landing site. I think the real issue is that they have many sensitive instruments and protecting against very small high velocity particles is difficult.
"These dust covers were one of the last things added to the rover. The MSL HazCams are build-to-print copies of the MER HazCams. On MER, the cameras were protected inside the lander, and in over 10 rover-years on the ground they haven't seen dust building up enough to be worrysome. The Skycrane system was supposed to reduce the plume ground pressure during landing to the point where dust wouldn't be an issue for MSL."
"But after Phoenix landed and everyone saw the pictures of pebbles ON TOP OF the pads on the bottom of the lander legs, and the legs themselves coated with a sticky looking layer of dust, some concerned folks looked at the issue more closely. It turned out there is a core flow in the Mars Lander Engines on the descent stage that stays strong all the way to the surface, even hanging at the end of the skycrane. And that can kick up a lot of dust+reaction products during the skycrane maneuver, some of which would go back towards the rover. There was a review of hardware in danger of being coated with "sticky" dust; everything was determined to be dust tolerant EXCEPT the HazCams."
I think it's mostly that they wanted to minimize any clouds from causing it to think it's closer to the ground than it is, and to keep the instruments from getting covered/clogged on landing.
But then the Viking landers had a full-up launch mass of 657 kg including full propellant tanks for the landing rockets.
Curiosity is 900kg just for the rover. If you added in landing rockets and their fuel as well it would be well over double the mass of a Viking lander, so the force of the landing rockets and therefore dust agitation would be commensurately greater.
Another advantage of a skycrane is that the rockets need to angled away from the payload anyway, and so the point where the plumes hit the surface is some distance from the payload, whereas rockets in the payload itself would hit the ground immediately below or to the side of it. Much closer.
It is my understanding that it is more about reducing the area that was affected by the rocket exhaust. The more area you mess up, the further you have to drive to find pristine surface. Yes, dust was stirred up over a small area, but if you took the rockets all the way down, you would disturb a much larger area, and probably change the surface chemistry around the landing site.
It does seem like there was a lot of dust kicking around. Was there anything said yet about if that was more or less dust than they expected? Maybe they don't even know how much dust is on the rover yet?
they seemed to be expecting dust on the hazcams, which i think i remember them saying (it was very early..) still had covers on them for the first shots.
Clear covers though, in case they didn't pop off as expected. Clever!
Somewhat related, and perhaps my favorite facepalm moment in space probe history: "...the titanium lens cap on Venera 14 landed precisely on the area which was targeted by the soil compression probe." (http://en.wikipedia.org/wiki/Venera#Venera_camera_failures_a...)
The cloudy stuff is dust from the powered descent. The top bit lowered the MSL down via cables which were 20m long, so the distance was short enough to blow up the dust but far away enough to not cause too much disturbance (they were worried about damaging the MSL)
Again, congratulations to the team responsible for that at NASA! Space exploration has advanced science like no other area.
What really rubs me the wrong way are some of those Youtube comments that go like "Why spend so much money on NASA?". Clearly, the spendings on NASA are minuscule compared to what the US spends on it's military or on the banks. That's a rather sad fact.
