Space Thread

[calapine]

Timelapsed video of the last ATV-5 'Georges Lemaitre' undocking for destructive re-entry. In colour and with a view of nighttime Earth in the background. Looks like straight out of a SF film...


Youtube 1m 22s

Edit: Sort of a waste of financial resources to develop, test and introduce something and then stop after building 5. And none of the potential enhancements were taken up: More cargo capacity, return cargo to earth, a manned version, etc ...

But 'no ambition' seems to be a general malaise in european space politics.  

[Morat20]

In random news, since it still comes up as an item in my department meetings...

You remember that quantum rocket concept? The reactionless (well, sorta) drive?

NASA is still testing that thing. They're doing vacuum testing and have been fighting their own equipment for months now. The critical test bits keep breaking down in vacuum before they can get enough data.

The measuring rig is complicated, but the theory behind it is pretty simple: Hang the suspicious space drive off a long rope, turn it on, see if the rope moves. :) IIRC, they measured thrust in air -- which could be random airflow (proposed thrust is very, very low) so they moved to vacuum. I'm honestly surprised they've still not finished the test cycle.

But every department meeting, it's still on the list as 'in work'. (My department isn't doing it. But we see what the rest of the engineering groups are doing). In any case, NASA is getting paid to do the testing, so someone else is paying for NASA to work out how to vacuum harden some new fiddly bit.

[HaemishM]

I'm sure even the data of how to vacuum harden something is a fucking goldmine to someone.

[Morat20]

I'm sure even the data of how to vacuum harden something is a fucking goldmine to someone.

NASA is fairly proficient at it. So is anyone who makes satellites. Something about the particular instrument they need to use, however, is just causing problems. I suppose they've never needed it to work in vacuum (probably never needed one this precise of whatever it is), so no one's engineered it for it. So they've been, basically, doing the usual "Fuck, slap some duct tape on it" method of getting it to work.

You  know, figure out what broke, slap a quick fix on it, start it up again, swear when something new breaks, fix that.....

Probably because building a special, vacuum hardened unit is way more than their test budget.

[Ghambit]

We have a temp/vacuum test-chamber at school (one of the few that do), for testing aerospace parts.   It's not that uncommon unless you want one the size that NASA sometimes uses.  Ours is small closet sized.  The Cubesat program uses it mostly these days; our project is collecting data on random bitflips due to cosmic rays.  Fuck me though, I have no time to work on it.

Recall, White is still working on his mini warp-field generator over at JPL too.  And the Diaz plasma drive is in full swing.  Exciting times; plenty of research monies out there w/o the shuttle program bogging us down.

[Khaldun]

Those bright spots on Ceres are getting more and more interesting the closer the probe gets. So far nobody seems terribly confident about what they are.

[Lucas]

Yep, can't wait for the closest approach :)

And also, while poor Pluto has been demoted to dwarf planet, other probes already went far beyond it (Voyager, Pioneer), I don't think we're really grasping how significant New Horizons' mission is going to be; finally, Pluto and Charon will be pictured, no more a white dot, since its discovery in 1930 (http://en.wikipedia.org/wiki/Pluto#mediaviewer/File:Pluto_discovery_plates.png). Plus, I put  my name in the CD that was boarded on the damn probe back when it was launched in 2006 

[01101010]

Those bright spots on Ceres are getting more and more interesting the closer the probe gets. So far nobody seems terribly confident about what they are.

Please be aliens... please be aliens.   

[jakonovski]

Shoggoths

[01101010]

http://www.space.com/29111-spacex-reusable-rocket-landing-test-video.html

Damn close. I am very curious as to the re-usability of a rocket given the stresses on all the joints and welds from liftoff to descent. In essence, once these rockets start hitting the return craft regularly, how usable will they be and how long before one of the reused rockets explodes because of a faulty weld that went undetected.

That said, this is pretty awesome regardless.

[Shannow]

Whats the bet that everyone in the Space X control room was leaning hard to one side as it came down.

[Quinton]

Better quality version of the second failed landing attempt:
https://www.youtube.com/watch?v=BhMSzC1crr0

So close.

And you can see the RCS thrusters at the top of the first stage trying (and failing) to correct for the tilt to the left, just before it tops over.

At a guess, I bet you could xray the entire recovered first stage (and do whatever other inspection you need) and check the integrity of it for a fraction of the cost of building a new one.  And you could probably recover the engine and other subsystems even if not the entire stage.  You only need to get one or two re-uses out of the thing to get some pretty hefty cost savings.

[Furiously]

The amount of fuel left in the rocket is pretty amazing.

[Ghambit]

They had a stuck valve that gave them less control over main thrust (either actuation or throttle), that's why the tilted landing and 'suicide burn' approach.  I think SpaceX is done with the whole barge thing.  Trying to land on a postage stamp in a rocky sea is not good testing imo.  They've proven they can get close, so it's time to give themselves some more cushion and come down on land.

Realize, a large part of the savings is having the landing site right near assembly in Texas no?  They may prove the concept at Canaveral, but the ultimate goal is to takeoff and land where they build the things.

[Furiously]

Bet they have nets that come up and trap it in on the next version :P

[MahrinSkel]

Ermmm....Texas is rather near an ocean, too. Pretty sure the water landing is the long-term plan, getting liability insurance for landing rockets in Texas...would be interesting. If all they wanted to do was 'prove the concept', they could have had it 'land' a hundred feet in the air over a buoy in the open ocean.

--Dave

[Quinton]

Landing on land is simpler in many ways compared to landing on a tiny moving target on the ocean.  My understanding is the barge would still be useful for flight scenarios where there is insufficient fuel to return to a land based site and it is useful for proving the capability in a more demanding environment first, but long-term landing on land and landing as close as possible to the plant is the goal due to the huge reduction in transport complexity, time, and cost.

[MahrinSkel]

It's *so* much simpler, why would you ever do it 'hard mode', if your plan was to switch to easy mode later? Not that I know what the long term plan is for certain, it just never occurred to me they would do the recovery ship at all if they didn't plan on using it after the test phase. Do you have a source for that, or are we both just speculating?

--Dave

[Chimpy]

Even if they get this right, space flight is a dangerous business. Landing in the ocean gives a margin of safety if something goes wrong as there is less chance of coming down on populated areas. They are also a private company so they are going to be much more concerned about liability than the government would be.

[taolurker]

I would think not only liability but also there's possible recovery of a failed landing on water, where impact on land.. Nope nothing but shrapnel.

[Polysorbate80]

I've lived in Texas (briefly).  There's considerable portions that can only be improved by exploding rockets above it 

Joking aside, there's plenty of areas where you're only in danger of toasting the occasional armadillo, snake, or tarantula without ever coming near the humanoid population.

[01101010]

I've lived in Texas (briefly).  There's considerable portions that can only be improved by exploding rockets above it 

Joking aside, there's plenty of areas where you're only in danger of toasting the occasional armadillo, snake, or tarantula without ever coming near the humanoid population.

True enough, but what if those things are on the protected species list? 

I'd think there would be plenty of places in the southwestern US you could land this rocket without putting humans at risk, but having the rocket fly over places to get to that spot does pose a risk.

[calapine]

It's *so* much simpler, why would you ever do it 'hard mode', if your plan was to switch to easy mode later? Not that I know what the long term plan is for certain, it just never occurred to me they would do the recovery ship at all if they didn't plan on using it after the test phase. Do you have a source for that, or are we both just speculating?

The long-term benefit of the barge is as Quinton said: it requires less fuel to reach a ship that is 'downstream' of the flightpath than performing a full return to the landing site. The reason they are (have to) using it exclusively now is safety. They need to demonstrate the ability to hit a target reliably before being allowed to do the same on land.

The real test IMHO will be the financial viability. The idea of reuse-ability isn't new (it was already considered for the Saturn V first stage). But executing it in a way that is safe and also less effort than just building a new stage is less easy. Two recent examples: A) The Russian Baikal is (or was) a proposed re-usable adoption of the new Angara rocket. But studies showed it would have required 40+ launches (per rocket) to be more economical than the single-use version. B) The Space Shuttle. The solid boosters had parachutes and were recovered & refurbished after each launch, but from what I read this never materialized any cost savings.

[Teleku]

The act of landing instead of splashing down into the ocean is the big part.  Refurbishing anything that lands in the ocean is very expensive.  The salt water fucks things up, and even with a parachute, the landings aren't actually very soft.  Obviously it still remains to be seen how viable this is, but landing the rocket is a major bonus for reusability.

[MahrinSkel]

They actually saved money on the occasions when the buoyancy failed and the boosters sank, as I recall. If it hadn't been all tied up with contracts and the way the enabling legislation was written in an effort to sell how 'reusable' the system was, they could have saved a lot of money with single-use boosters.

If they can actually perfect the soft landing and make a system that just needs new nozzles and general maintenance, then it will certainly change the cost structure.

Looking into it, I don't see how dry landings are feasible. In addition to the safety issues, the problem is that the booster stage does not, can not reach orbit, it's going to come down well east of the launch site unless you burn a shitload of fuel. So you're not landing in Texas unless you launched from Baja California. You could launch from Texas and land in Florida, maybe.

Would make more sense to have a half-dozen drone landing ships you could space out around the potential landing zone so that nothing short of a major hurricane would render them all unusable. But I don't think you're going to get zoning permission for a rocket landing site any time in the immediate future.

--Dave

[ajax34i]

They need 4 poles in the corners of that platform, with 4 arresting cables that can basically lasso that rocket from 4 directions and hold it upright in the center of the platform.  Or maybe the rocket can deploy its own anchoring cables.

[Morat20]

Somebody needs to develop anti-gravity. Or a way to cancel mass. Or some other way to flip physics the bird.

Or, less fantastical, just say "Fuck it" and build a space elevator.

Only two major roadblocks to go! Fiber length -- they can't grow the carbon nano-tube fibers as long as they need, but they're making steady progress. And, of course, the problem that there's a lengthy phase in construction where the ribbon is wide enough to be really likely to get hit by micro-meteorites, yet not so wide it'll survive until the next constructor up repairs it. (After a certain width, it doesn't matter. Crawlers going up and down repair the ribbon as they go, and the damage won't be big enough).

Of course, that's only the first one. After that, you can ship the ribbon up the first elevator and drop it down.

[Merusk]

Of course, that's only the first one. After that, you can ship the ribbon up the first elevator and drop it down.

I keep seeing people say this and yet no explanation of why you can't do the same with the first. Drop it from the ISS or another fixed-orbit object vs. build it up to them.

[Shannow]

Weight?

[calapine]

I keep seeing people say this and yet no explanation of why you can't do the same with the first. Drop it from the ISS or another fixed-orbit object vs. build it up to them.

We can't actually build a space lift yet. None of the proposed materials are really mature enough.

Re: Dropping down from ISS: The ISS is at ~400 km height. A space elevator needs go up to GEO ~35000 km to have enough centrifugal force. And that loops back to the first sentence; building a 35000 km long cable that can sustain the weight (and the environment conditions of space) isn't a minor undertaking.

[MahrinSkel]

Essentially, yes, the mass of the entire beanstalk is way too much to lift on rockets, you have to lift just enough for the first strand, then use that.

--Dave

Edit: Much easier, in terms of energy, to nudge an asteroid with the right composition into GEO, if you can find an Earth-crossing rock that fits the bill. Especially if they can make the microwave thruster/Cannae drive work in practice

[Morat20]

Weight?

Yep. 35,000 miles of very, very, tiny thin thread. You can't lift a full of even partial ribbon.

Once you have the thread, you start sending crawlers up (small ones at first) to weave a second strand. Using beamed power.

We actually do have the proper materials -- we can make carbon nano-tubes that have the right properties, but we have to make tubes of a certain length to make it work (a foot or so, I think? It's been ages) and they best we can do is less than half that.

[Merusk]

Ah, the distance is farther than I thought, so I get it now. I thought, "send up 400-800km of carbon monofilament across several trips for the ribbon.  That's not overly much, right?" 35000 km is a bit different. Newp! Thanks.

[pxib]

New theory on mysterious radio signals:

Earlier this year, Swinburne University's Emily Petroff was the lead author of a report on the first observation of a fast radio burst (FRB) in real time. Previously, the enormously powerful but poorly understood events known as FRBs had only been detected in the records of large radio telescopes years after they happened.

However, among those records was something else, which astronomers named perytons. The first peryton detected was in 1998, although it was not recognized as such until 2011. Perytons look sufficiently like FRBs that astronomers even speculated that the first FRB, known as 010724, might actually have been a peryton.

Perytons last about half a second and are “frequency-swept,” meaning different frequencies arrive at different times, which in perytons's case means the high frequencies appear first. Petroff says, frequency-sweeping is commonly associated with signals that have passed through an interstellar medium that has delayed certain frequencies more than others.

However, while FRBs are believed to come from outside our own galaxy, perytons were thought to be terrestrial in origin, since they registered on multiple beams of the radio telescopes, something that should only be possible for events that are very nearby or spread across a huge area of the sky.

So she did some experiments, and figured out what was happening:

[Samwise]

Weight?

Yep. 35,000 miles of very, very, tiny thin thread. You can't lift a full of even partial ribbon.

Once you have the thread, you start sending crawlers up (small ones at first) to weave a second strand. Using beamed power.

The mental image of tiny robotic spiders spinning a web into space for us to climb makes me feel all warm and tingly in my nether regions.