SpaceX Falcon tests hovercraft tech – despite ISS outage NASA has said that SpaceX's latest cargoship launch to the International Space Station will go ahead, despite a critical computer outage on the station, allowing the firm to test the craft's hovering abilities. Mounting landing legs (~60 ft span) to Falcon 9 for next month's Space Station servicing flight pic.twitter.com/ …
Are they so unsure about ending in the right place? Otherwise, why not do it on the ground in the middle of the desert? Even if it ends up exploding, it seems a better simulation…
And if they are really unsure about controlling the rocket, it seems hardly worth it to add legs to it, considering the only thing they plan to do is to hover gently above the ocean before sinking it.
They have already done many hover tests with Grasshopper - what they really need is a test with all systems in place. There are plenty of aerodynamic issues that are affected by the legs, so yes, it needs them on there to be a representative test.
As for landing in a desert - possible, but much much safer to test at sea. To get to a desert, you probably have to overfly something that you probably don't want to land on by accident. And the sea is much bigger so harder to miss.
With rockets, its always best to err on the safe side.
To rendezvous with the ISS, you must launch into its west-to-east orbit, which in the U.S. means from the east coast to avoid launching over people. The launch vehicle will be many miles out to sea at separation, and has to fly back to land, something that has not been thoroughly tested yet. So they'll "soft land" it on the water and then try to recover it. The shuttle's SRBs were lowered by parachute into the ocean, and then recovered and reused for decades.
The goal is to have Falcon's recovery systems reliable and accurate enough to fly back to sparsely populated coastal areas and land softly enough to be reused. This is just the first operational test of that goal.
If it was me I'd be tempted to have a barge or flat-decked cargo ship in place at the expected landing area, then if the approach was going well tell it to land there - otherwise you could choose/be forced to miss and land it in the sea anyway.
Seawater and complex systems are a bad mixture, why dunk it if you can help it?
I wouldn't. Same problems you have landing a fighter jet on a carrier: the deck is constantly in motion. That complicates the landing way beyond the test parameters. Sea water may be bad, but a busted ship and a busted barge are even worse. And that's your likely outcome. Plus, you may still have to deal with sea water anyway.
"why dunk it if you can help it"
Not disagreeing with you but if you can't land it safe on earth where can you land it safely?
I can't see why Russia is set on going to the moon for its next project nor any of the stupid things the Chinese have been doing just because they can.
Why don't the lot of them get together and work on doing something they can't, much nearer home?
War easier to maintain than peace, is it?
"The launch vehicle will be many miles out to sea at separation, and has to fly back to land"
Surely having the launch vehicle 'fly back to land' will require more fuel plus some guidance systems, that's lots of exra cost. If taking off west to east from Florida, why not buy up an area in another country to land the rockets in? The first available landmass east of Florida is Sahara desert, plenty of sparsely populated wasteland that could be bought on the cheap.
"Then you have to add the cost of getting the rocket back to the launch pad....might as well take the hit up front and fly back."
It's not only monetary cost though, it's also cost of fuel/range of the rocket itself. If you land east of the Atlantic and have to ship the rocket back, the overall cost in both fuel and $$ will be higher, BUT you're spending the extra fuel on the surface and get to have more payload on the rocket
"Are they so unsure about ending in the right place? "
Not really. They're worried about it staying under control as it falls, like the last Falcon 9 (September '13) landing mishap. The falling first stage went into a roll beyond the ability of its thrusters to control and tumbled to the water. Hitting the bullseye was less of a concern, since SpaceX's aim was pretty good by that point.
"Otherwise, why not do it on the ground in the middle of the desert?"
Because this rocket launch is to service the International Space Station under contract from NASA, and thus this Falcon 9 needs to launch from Florida to keep SpaceX's customer happy. Other than some metaphorical moral deserts in Miami and Orlando, Florida doesn't really have a desert for rocket testing. However, Florida does have a lot of test range infrastructure and Snark Infested Waters that have been receiving test rockets for decades. Beyond keeping its paying customer happy, SpaceX is piggybacking this launch to try out landing hardware and protocols, but that's purely secondary. Get stuff to the ISS first, play Harrier second.
Further, SpaceX is paying attention to rocket design history. The first bits of rocket hardware rarely work as planned even after hundreds of tests in the lab. Rather than trying to get all the widgets and gizmos to work right on just the second try, SpaceX is only testing a limited number of features (thus minimizing variables) on this flight. The flight in September failed for a reason. SpaceX'd like to make sure that reason is solved and try out a few new things. Actually getting everything to work for landing is going a bit too far, and they've got a Grasshopper to test reusable flight (in a desert, in fact).
"considering the only thing they plan to do is to hover gently above the ocean before sinking it."
Considering that hasn't been accomplished previously, that's not an "only thing." The last time SpaceX tried that the rocket went into an uncontrolled roll and crashed. (Also into the ocean, since the paying customer wanted a launch from California into a polar orbit.) And despite that, SpaceX was very happy with the September flight. It gave them mountains of information about real world aerodynamics of rocket stages falling arse-first from space and important lessons about residual fuel behavior. (The crash was caused by fuel 'whirlpooling' in the fuel tanks.)
It might not seem like much to have a rocket land vertically on telescoping legs, but that's actually an achievement involving a huge amount of engineering addressing thousands of problems in a handful of test flights. That's quite different than testing a new car airplane design, where you can fly or drive the vehicle thousands of times before beginning to sell them. You're condensing a lot of mistakes into a few flights, and crashes are to be expected.
That Professor Goddard with his chair at Clark College doesn't know of the relationof action and reaction and the need to have something better than a vacuum to push against.
http://astronauticsnow.com/blazingthetrail/gruntman_btt_pages/gruntman_blazingthetrail_p_117.pdf
Bollocks too to the Registers timeline for an edit. You bastards.
That was certainly the case with the Space shuttle. Cost a bloody fortune to get it ready for the next flight.
Estimated cost of the F9 reusable 9 engined first stage is $30M or I believe. Don't have to reuse it many times to get your money's worth (and you can afford to replace an engine or two). And it only carries about $150K worth of fuel....
Expected turnaround is a LOT faster than something like the shuttle.
Resources maybe, money is quite often a wash. Remember it frequently costs more to fix things than to make them from scratch these days. And I say that as someone who'd really rather fix than replace in most instances.
Since the only long-term value of money is as a proxy for finite resources, this says more about the weaknesses of our economic systems than it does about the validity of the reuse philosophy.
"Until the US pork machine got involved, the shuttle was intended to be air-launched from a manned mothership, in much the same way as Virgin Galactic are planning."
No. what screwed the STS design was the Office of Management & Budget's requirement that no yearly expenditure exceed $1Bn. IE not enough for 2 different stages.
That budget profile is completely unlike any real space (or indeed large infrastructure) investment programme.
With only enough money to develop 1 complete new stage and engine the design was one of only (possibly) 2 that could be afforded.
All the other designs went in the trash with that funding profile.
The top level MDM's have IIRC on board 386'x (but they might have had an upgrade).
Otherwise Multiplexer/DeMultiplexers collect data or receive commands through a pair of network links and route them appropriately. I think they have some kind of internal filtering and caching functions but they don't actually have an on board processor.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2025
