They’ve launched the Falcon Heavy three times so far. They’ve got a launch scheduled for later this year and two or three for 2021.
Interesting how some early sci fi movies showed rockets landing the same way they land the stage 1 on ships but that never happened in real life until recently.
What measures do the drone ships use to mitigate rough water? Are there any interesting mechanical stabilisers being used?
Snarky answer: because there aren’t any ships on land.
I think the safety aspect is the best one. No technology is immune from failure, attempting a landing on land could be disaster if things went south. Mechanical failures are not impossible, landing in the ocean will at least ensure that life and property are not at risk.
The ship manages its location with GPS guidance. However, there doesn’t appear to be much in the way of pitch/roll stabilization. Here’s the video I linked to upthread, cued to 7:35, at which point you’ll see a freshly landed booster skittering precariously around the deck as the drone ship heaves in rough seas.
Early on there was talk of recovery crews welding shoes over the booster’s feet to lock it down to the ship’s deck before towing the whole rig to shore. I don’t know if they’re doing that these days, but in this photo you can see that they’ve chained the booster down to the deck.
SpaceX routinely lands its rockets on land. (Here’s a YouTube video showing such a landing.) As already noted, they only do the ocean landings when they have to because the mission is such that they can’t easily get the rocket back to Cape Canaveral; landing the rockets at sea adds complexity to the mission in several ways (landing on a target that may be moving up and down and sideways; having to haul a rocket–which is still standing upright–all the way back to Florida from hundreds of miles out to sea).
They had plans to land the crew capsule on land and water but now they are only going to use water splashdowns like NASA did pre space shuttle.
The Sky Calls (1959 film) has a scene that’s remarkably close, even to the point of it being a barge.
It’s likely that the control systems needed for landing wouldn’t have been sufficient until recently. Not just the hardware, but the software, and the mathematics backing it. Lars Blackmore drove the field forward significantly and is the lead for EDL (entry, descent, landing) at SpaceX. Even relatively recent test vehicles that did tail landings, like the DC-X, probably were not sophisticated enough for a full reentry program and hoverslam landing.
As an aside, Blue Origin plans to use a much larger ship, which will be in motion during the landing. The advantage is that it can use fins to stabilize the ship and reduce pitch and roll.
They use the OctoGrabber now to lock it down. It’s a remote control robot that grabs the rocket from below.
OK, so the Octograbber grabs the ass end of the rocket - but how is the Octograbber tied to the deck?
As far as anyone can tell, it’s just heavy. The empty stage only weighs 20ish tons, and the mass is already concentrated near the deck (the engines). A flat plate that’s even nearer the deck and adds another few tens of tons should be sufficient.
It’s not impossible that it uses magnets or thermite charges or something, but it seems unnecessary.
Apparently 25 tons. And yeah, if it’s hugging the deck like that, I suppose that’ll do a nice job of lowering the center of mass. Maybe even adding some grip with rubber tires so the whole rig doesn’t slide around on the deck in rough seas (like the Falcon did in 2016).
I love the Culture reference. I hope they keep naming things like this.
It has treads, so quite a bit of surface area to grab the deck. Way, way more than the landing legs.
I suspect the pads on the legs are pretty slippery, too–you would want them that way, so that as they touch down and the shock absorbers compress, they can slide out a bit without causing unwanted forces. Or if the booster has some small lateral velocity as it touches down, you would want it to slide across the deck rather than sticking.
The OctaGrabber can just be… not designed to be slippery. It doesn’t need immense sticking force, just better than what the legs provided.
There’s a new ship under construction, A Shortfall of Gravitas. That did not precisely appear in the books, but various gravitas-related names were (Very Little Gravitas Indeed, Experiencing A Significant Gravitas Shortfall, etc.) were, so it’s very appropriate.
As an aside, how will SpaceX be affected by the Covid induced depression?
Artemis is probably a goner, if history is any guide, Constellation was lost in the post financial crises budget cuts, Apollo was truncated due to the early 70’s slowdown.
Hard to say for sure, but a permanent increase in the rate of working-from-home sure seems to benefit Starlink. Especially combined with any kind of urban->rural flight (no idea if there’s any evidence of this so far, but it’s not hard to imagine).
COVID seems far more likely to pick off SpaceX’s competition than SpaceX. There are a zillion little startups that will collapse if VC money dries up. SpaceX would like to grow as quickly as possible, but they’re in a strong position and can take a funding slowdown.
It’s not clear that there will be any such slowdown, anyway. Look at Tesla: now the most valuable automaker on the planet (by market cap), after announcing that they had almost no drop in sales in the last quarter, as compared to other automakers that experienced a 30-40% drop. The market rewards this kind of resilience. SpaceX is private of course, but institutional investors still want somewhere to put their money and SpaceX appears less fragile than just about everyone.
Hadn’t they bet heavily on getting cintracts to build and launch Artemis infrastuture? Lunar gateway has been cancelled and the new Apollo style LOR needs a lander which would be a lot less profitable.
Sure USAF and Space Force launches are not going anywhere but delays are likely and foreign projects might get cancelled.
The lunar gateway hasn’t been cancelled, and SpaceX wasn’t betting heavily on it in any case. They are planning on slapping together a variation of the Dragon capsule, called Dragon XL, that would be more cargo-optimized. But this was never going to be their main business.
NASA also awarded SpaceX a development contract to land Starship on the moon (in a program which bypasses the Gateway for the time being). Since SpaceX was already developing Starship, this doesn’t change their plans at all. The extra money is nice but not enough to be make or break.
Where things may get interesting is that NASA plans on setting a cost-per-ton price for cargo delivered to the Moon. This highly favors SpaceX, because there is no price at which SpaceX doesn’t either earn all the business (because competitors with non-resusable rockets can’t be profitable at that price), or is wildly profitable (because for any price where the competitors aren’t losing money, SpaceX will be making money hand over fist).
Compare to the Commercial Crew program, for example, where for essentially the same project, Boeing got $4.2B and SpaceX $2.6B. And for which, I might add, SpaceX roundly beat Boeing.
So it’s fantastic to see them be on equal price terms. And even greater is that it’s a huge incentive to lower costs further–every dollar they same is more money for other projects. And it means that once said cost reductions happen, NASA can reduce their cost-per-ton even further. It’s a virtuous cycle, at complete odds with the traditional cost-plus accounting and better even than the current style where NASA funds in-house development but does not micromanage.
Anyway, as I said the big moneymaker will be Starlink. This will be tens of billions a year; much bigger than the rest of their business combined. OneWeb is bankrupt and won’t be competition; nor would they be competition anyway because they cannot come close on launch costs (even now, let alone when Starship arrives).