Slashdot Mirror
NASA: Revolutionary Camera Recording Propulsion Data Completes Test (theverge.com)
An anonymous reader quotes a report from The Verge: NASA has created a camera that can film slow motion footage of booming rocket engines with higher dynamic range than ever before. It's called the High Dynamic Range Stereo X camera, or HiDyRS-X (PDF), and late last week the agency released some of its footage to the public for the first time. The three-minute clip shows the most recent test of one of the boosters for NASA's upcoming Space Launch System rocket in unprecedented detail. SLS will use two of these 17-story tall solid rocket boosters, each of which is capable of burning 5.5 tons of propellant per second to create 3.6 million pounds of thrust. The problem when it comes to filming tests like these (and eventually, launches) is that the plumes of fire they produce are extremely bright. This usually leaves camera operators with two choices. They can either expose the footage for the bright plume, which will leave everything else in the shot looking dark and underexposed. Or they can expose for everything else in the shot, which leaves the plume looking bright white and void of detail. The HiDyRS-X camera solves this problem because the camera can capture all of this detail in one shot, and it does this in a fairly clever way. Where regular high-speed cameras usually only captures video one exposure at a time, HiDyRS-X can capture multiple exposures at a time. NASA did however report some failures with the test: the camera's automatic timer failed to go off, thus failing to record the igniting of the rocket, and the pressure being generated from the booster knocked the camera's power source loose.
Come on, this is a science article, and you are even not able to use metric, or at least some imperial measure.
No, stories. WTF???
How many statues of Liberty is that? So I can multiply with 92.99
Atari rules... ermm... ruled.
If it were affordable. It's not, particularly at the sort of budget levels on hand. So only rarely going to be used. So it'll never have economies of scale or the refinements (including safety) that come with having a long launch record.
Everyone tries to design missions to use it, though, to try to get buy-in to their plans, knowing that due to pressure in congress they want to find excuses to use SLS as much as possible, even if financially the option doesn't make sense. Example: I was reading some of the followup work on HAVOC the other day - HAVOC being an evolutionary approach for manned missions to Venus that a couple people at Langley have been promoting. Now, when I read their initial proposal, I could tell that clearly their call for SLS to launch the airship was way overkill. The entire hull (including the envelope) is 6455kg (and they call for the transfer stages and aeroshell to be launched separately). Throw all of the other mass of the airship (not counting the separately launched return rocket), such as propulsion, helium tanks for inflation, etc, and it's still only 25772kg. Obviously you don't need SLS to launch a 26 tonne payload to LEO. They describe it instead as being volume limited due to the volume of the fabric. They have something in the ballpark of 15k m surface area. They don't give their fabric thicknesses, but the heaviest Venus balloon fabric I've ever seen proposed on any mission was VALOR's, which is somewhere around 120um thick (most are much thinner than VALOR's). Using 120um as a baseline, with a perfect packing ratio, 15k m would take up 1,8 cubic meters. Multiply it by whatever factor you want to account for imperfect packing - you'll never come anywhere close to the need of SLS's 1100 cubic meter fairing.
In their followup, they pretty much confirmed this. They did a (very) small scale folding experiment, using the fabric they were proposing, at the thickness they were proposing. It fit into their accordingly scaled-down SLS fairing. Now, clearly, if you're scaling down your fairing volume and vehicle, but you're not scaling down your fabric thickness, then you're going to end up with something that takes up vastly more volume. Yet it still fit. So clearly they don't need anywhere near all that space**
** - Caveat: I don't know if they don't understand how blimps work or what, but they have no accounting for ballonets nor catenary curtains in any documents they've released that I've come across, nor do they compensate for the former with superpressure or phase change fluids, or the latter with a rigid keel or frame. Obviously ballonets and catenary curtains also are a source of mass and volume. But again, nowhere even close to mandating SLS.
This is hardly the only case I've seen like this. It seems like it's popular to try to baseline SLS into missions to try to get support for those missions. Whether or not SLS is actually needed. They know that they can always remove the SLS requirement if/when the system gets cancelled.
No, she's fine. My associate is vomiting for a totally unrelated reason.
I saw the recordings on different outlets -- but here might be the right place to ask: the exit velocity is quite impressive, but in the recordings, it seems to me that to the middle and right end, some structures look almost stationary. Can anyone of you judge if that is a visual artifact of the camera (which would make it somewhat useless I think), or an actual physical phenomenon?
Very impressive footage, although I would have loved to see the initial ignition and the fadeing at the end.
What I'd also like to know is if igniting rockets such as these horizontally, with this amount of thrust, would have any measurable impact on the earths rotation at all. If not, what amount of thrust would be needed to do this?
To Terminate, or not to Terminate, that's the question - SCSIROB
And let's not mention the fact that they couldn't get the timer to work (!!!), so they missed the ignition, the power source was knocked off so they missed the end, and also it is kind of shaky... So not that great of a test even as far as cameras go! ;)
Meanwhile two private companies are building rockets that can land themselves...
But, yeah, who needs NASA as long as we have our drones and our F35s
Violence is the last refuge of the incompetent. Polar Scope Align for iOS
The most I've found so far is the short
Note that an HDR video camera is not in and of itself particularly "revolutionary and innovative", and there's no indication of how the NASA camera might differ from existing offerings (higher frame rate? better dynamic range? more "scientific-ness!"?). But when fighting for budget the more clickbait one's research generates the easier it is to convince a politician to fund it - so everything becomes "revolutionary." (This is the science and engineering PR version of the music industry's "loudness war.")
Anyway, revolutionary or not, the rocket is big and the pictures are pretty.
"Game Changing Comment Uses Disruptive Technologies Based On Emerging Advances To Bring Revolutionary Full Stack Vacuity To Slashdot."
Can't you just use several cameras?
My thoughts exactly.
I have a Panasonic sub-compact camera with a mixed-light setting that that takes multiple exposures of the same scene and processes them together into one properly exposed image. This NASA camera sounds like it's doing the same thing on a different lighting scale [and built to withstand rocket blasts]. I'm sure it's a useful tool for anyone working with rockets, but how news worthy is it?
So it seems they have per-pixel exposure control, rather than a full-frame exposure control.
Not sure how that works, perhaps instead of letting the charge build up on a cell and then read all the cells after time T, they time how long each cell takes to charge, and after a cutoff time T, measure the charge of the remaining cells?
The idea being you use the time-to-saturation as a measure of brightness for over-exposed areas, while the traditional charge level for the well-exposed areas.
First thing that popped into my mind, but then I don't really know the area so yeah... may be a very stupid idea :)
Good thinking. You sound closer to being correct than my other proposals in this thread.
Common HDR is "Video based on a per-frame variable read rate". That is, instead of 30 fps or whatever, the sensor progressively reads in a logarithmic progression of 'frame rates', on a per frame basis. For example: 0.1 ms read, 1 ms read, 10 ms read, and then a 100 ms read. HDR software processes these four sub-frames into a single HDR frame, but it is really a capture of four different time-spans.
Pixel-based exposure settings, regardless of 'frame rate', could work. But... You would have to read them to know when they saturate. It would probably also lead to blooming around the high-exposure pixels.
That being said, if one just records at 10,000 fps and 24-bit, or whatever, and then uses software to "time-stack" the frames, adding up "dark pixels" across frames until a threshold is reached, would provide pixels of the low-lighting objects (which are not moving much, BTW). Single pixels read at near-saturation would be used individually, or perhaps averaged over several reads. Result, HDR without the time-smear!
It's amazing that it took so long for someone to implement this (AFAICT). OK, truth be told, we in scientific imaging do this all the time.
speaking without any knowledge here,
wouldn't it be easier to have multiple chips capture the image at different exposures at the same time and use software to blend. is there a rule that one camera can only have one chip?
Sure.
Your Canon EOS has a half-silvered mirror at 45, allowing the little viewfinder to see what the optical column (lenses and film) see.
We do this with laser interferometry measurements all the time. Why not use a set of four to send the identical image to four different detectors, each with a different sensitivity (via attenuators, timing, optical-sensing device-type)?