Kryten
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Posts posted by Kryten
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3 hours ago, RainDreamer said:
I wonder if quantum computer require much more hardening against cosmic radiation considering how sensitive the q-bits are.
It isn't handling q-bits, only entangled photons. There's not a lot of real cross-over between quantum cryptography like this and quantum computing.
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The Chinese have launched the first satellite for quantum communications, Mozi, into a 600km sun-synchronous orbit. The satellite is designed to facilitate transmission of entangled photons from a ground station in Beijing to one in Vienna; this would allow quantum key encrypted communications over about 7,000km, versus the current record of a few hundred kilometres over fibre. The satellite is also intended to demonstrate quantum teleportation over this distance, again compared to current records of a few hundred kilometres. According to one of the physicists on the team, the satellite could be followed by others if successful, allowing transmission of quantum information across the globe.
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Was. Oka-T was cancelled as part of the 2015 shake-up of the long-term federal space plan. In theory Energiya could do it with internal funds, but in practice they haven't got any.
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Some crystallisation experiments, for example, wouldn't be viable on ISS because the microgravity isn't good enough; all the people moving around and the pumps for the life support system degrade it quite badly. Still, Energiya couldn't find enough examples of experiments sensitive enough to do Oka without government funds, and SpaceX haven't found enough to do DragonLab. With New Shepard on the cusp of operation and able to provide clean microgravity for very cheap, we can expect there to be even less experiments requiring this kind of capability.
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This Martin guide to the MMU gives the translational acceleration capability as 0.3 feet per second, which translates to about 0.01g, less than a tenth of what you'd need to hover on the moon. KSP jetpacks do thirty times that.
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That looks like a solid kick motor on their sat, they're going to have great trouble finding somebody willing to rideshare with that. A dedicated Electron launch could work.
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1A wouldn't be any cheaper than 1B, it was just another upgrade path they were considering. They went with 1B because the accelerations with 1A would be too high and they'd have to add extra structural margin.
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21 hours ago, DDE said:
I have no idea what you have on that photograph. That isn't a four-stage Proton variant, and it seems to be burning kerolox, not UDMH-N2O4.
The image source claims this is a 'press release photo' from the launch; the Proton design was a secret until the televised launch of the Mir base block in '86, so it's plausible this is something the soviets mocked up at the time. It doesn't match any real rocket I've seen.
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It wasn't an official end-of-mission statement, read the post I linked. This whole thing is from one semi-official Weibo post (effectively Chinese Twitter), which said the mission may be over. That's true, in that this night could kill the vehicle, but that was also true for the last 32 nights.
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Best is to keep your eye on the NASASpaceflight forums, they have good standards for posting and a very professional userbase. Easiest way to get this info at a glance is the SpaceX manifest thread.
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2 hours ago, Jovus said:
Does anyone know where I can find information about JCSAT-16, like whether SpaceX is reflying a booster, or whether it's a barge landing or RTLS?
No reflight for a while yet. JCSAT-16 is just about identical to JCSAT-14 earlier this year, so barge landing.
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One tidbit from the conference that hasn't turned up here is that the FH launch for STP-2 has been delayed to Q3 2017. Given that's only meant to be the second or maybe third FH flight, don't expect to see FH going up anytime soon...
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A representative from SASTIND has clarified the situation; the last signals were detected on July 28th (this year), and the vehicle is currently in hibernation for the lunar night. The statement about 'no data' is because the last instrument had ceased to function, but the rover itself has still been functioning.
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An article on lessons learned from the Super Strypi failure has been published, including preliminary results from the failure investigation (P. 13).
QuoteSpin stabilization worked as designed from initial rail launcher separation through maximum dynamic pressure and at least one significant wind shear. Roll rate was nominal through the first 47 seconds, except for initial spin-up nearly twice as fast as expected through the first 10 seconds of flight then returned to as predicted. However, spin stabilization also doomed the mission as the first stage motor proved insufficiently robust. In summary, use of spin stabilization in the Super Strypi design is unproven and ability to successfully implement on future launches is beyond current analysis capabilities. Any future launches will require a design change to the first stage motor and possibly to second and third stage motors.
[...]The most likely cause of the launch vehicle anomaly was breach of the first stage motor case due to slag build up in the aft end of the first stage motor from vehicle rotation leading to increased insulation erosion. -
10 hours ago, cryogen said:
It's probably invisible, actually. Hydrogen gas has very little emissivity; it's transparent and doesn't glow when heated. Check out photos of the RS-25 engine (shuttle launches, or SLS engine tests); they're almost totally invisible, except for a faint blue glow. Even that glow is probably caused by steam (this person suggests chemiluminescence from radical recombination, I assume OH radicals), and wouldn't show up in a pure-hydrogen exhaust stream.
RS-68 engines, by contrast, have an orange-pink glow, despite using the identical LH2/LOX fuel as RS-25. The difference is that RS-68 is an ablatively-cooled engine, which means the engine nozzle liner is slowly vaporized to provide evaporative cooling. It's this ablated organic material in the exhaust stream that makes it colorful.
I suspect the pink color visible in NTR ground tests is also caused by something ablating; I don't know. If a flight NTR engine involved something ablating, then that could introduce some color; maybe it'd look like RS-68.
What causes the yellow glow of hydrolox engines at low thrust settings? This can be clearly seen in images of DC-X or New Shepard landings. Given in both cases easy reuse of the engines has been demonstrated, it's very unlikely to be anything ablating.
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3 minutes ago, Gaarst said:
So thinking SpaceX is doing better than someone else on a single discussion and you're a SpaceX fanboy
Saying that doing subscale tests isn't going to help makes you just about delusional, whether you call yourself a fanboy or not.
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On 03/08/2016 at 8:02 AM, Duski said:10 minutes ago, Firemetal said:On 02/08/2016 at 11:57 PM, tater said:10 minutes ago, Firemetal said:
Again, very good point. BO was founded two years before SX so they had two years to think of it first. However they most likely thought it up at around the same time as SX did since they both started around the same time.
As said above, they should not be compared. (Elon was a bit arrogant
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We know Blue were working on VTVL well before SpaceX, because we have patent fillings and early treat vehicles like Charon. All early SpaceX material referred to recovery by parachute, and that was the plan well into the early operations of Falcon 9. Maybe they had thought about it earlier, plenty of people had, but there's no proof of it being the actual strategy until about 2011.
(Sorry about the extra quotes, forum bug on mobile. Can't delete them.)
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8 hours ago, Gaarst said:
The fact SpaceX started with Grasshopper and is now recovering its Falcons shows that SpaceX is more advanced than BO. Learning to recover on smaller launchers is fine, but BO has yet to prove that its multiple recovery "tests" will be useful for orbital missions.
The idea that the lessons won't apply is, quite frankly, absurd. The only major difference between what F9 does and what NS does is F9 has a significantly higher re-entry speed, the demands on most subsystems are about the same. The only thing F9 really has that NS doesn't is thick ablative TPS, and even then the TPS isn't some secret sauce bit of technology, it's bloody cork! If you're making this kind of argument, have a good long think about why you're making it; if you just want to defend St. Musk and his precious company, stop it, they really doesn't need it.
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37 minutes ago, Gaarst said:
I believe SpaceX's approach of first recovering, then reusing, in real flight conditions is more prone to eventual success than BO's approach of recovering + reusing in vertical flights with a test launcher and then switching to a totally different launcher with totally different launch parameters and hoping stuff works the same way.
That doesn't make a lick of sense. SpaceX also started with vertical flights with a very different launcher, Grasshopper; do you think they'd be doing better now if they hadn't done those flights?
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Atlas gives that plume because of water in the exhaust; Soyuz second/third stages and Falcon 9 give similar ones. A pure hydrogen plume might still be visible, depending on how diffuse it is (amateurs get photos of hydrogen plumes from centaur stage fuel dumps all the time), but you won't get a massively visible 'jellyfish' plume.
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Strong engine gimballing. If you watch carefully you can see the rocket tip just after ignition, before the gimballing kicks in.
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1 minute ago, Duski said:
Oh. So did a basically perform a sub-orbital flight in the atmosphere? Well I did read something about the grasshopper somewhere.
By posting on this forum you've clearly demonstrated you've got access to the internet, so why are you asking such basic questions? Google and the wiki are quicker and easier. Heck, the wiki article on grasshopper would've answered all your question thusfar.
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Grasshopper didn't even pass the 1km mark, and F9R-dev barely did.
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2 hours ago, Duski said:
Saw what you linked, and he did say some thing he shouldn't have but I guess he is defensive of his grasshopper rocket doing 6 sub-orbital flights whereas New Shephard only doing 4 (According to Wikipedia). At my perspective it looks like a popularity contest.
Grasshopper hasn't made any suborbital flights, it hasn't even been close to beating the DC-X flight record. Masten has been making more frequent flights to higher altitude for years, so by your methodology we can assume Musk is just being defensive about them...
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Quantum Science Satellite (Mozi)
in Science & Spaceflight
Posted
The sat isn't just a bent-pipe relay, it's also set up to produce it's own entangled photons and transit them to both ground stations. More info here.