SpaceX will try to 'catch' its Super Heavy rocket using the launch tower:
SpaceX might not rely on legs to land its next-generation booster rockets. Elon Musk has revealed that his company will try to “catch" the future Super Heavy booster using the launch tower arm, with the grid fins (used to help control the descent) shouldering the load. As TechCrunchexplained, this process would effectively hook the rocket using the tower arm before it reaches the ground.
This would require very precise positioning, and there's still a long way to go when Super Heavy flight testing might not start until a few months from now at the earliest. If successful, though, the catch method could save SpaceX from adding bulky legs to its rocket. A truly precise maneuvering system might even reduce turnaround time by letting SpaceX relaunch the rocket without having to move it from its landing position.
We're going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load
— Elon Musk (@elonmusk) December 30, 2020
According to the article on TechCrunch:
The Super Heavy launch process will still involve use of its engines to control the velocity of its descent, but it will involve using the grid fins that are included on its main body to help control its orientation during flight to "catch" the booster — essentially hooking it using the launch tower arm before it touches the ground at all. The main benefit of this method, which will obviously involve a lot of precision maneuvering, is that it means SpaceX can save both cost and weight by omitting landing legs from the Super Heavy design altogether.
New Atlas mentions that:
In a follow-up tweet Musk revealed this approach would not only save money and mass by removing the need for the booster to have legs for landing, but would also allow it to be immediately repositioned onto the launch mount for reuse. Musk added that this would allow the booster to be "ready to refly in under an hour," which sounds overly ambitious, but Musk and the SpaceX team can never be accused of aiming low.
(Score: 5, Interesting) by Barenflimski on Monday January 04 2021, @10:08AM (19 children)
NASCAR pit stops meet Musk. I love the ambition.
In reality, it takes about an hour to fill up the tanks. It would be interesting to know if the heat from the re-entry burn would add time to this as one might need to cool the spacecraft down?
This would require some sort of fast-payload switching gear. I'd imagine one would need equipment onboard the launch vehicle that would allow a quick change out. I would imagine one would need to erect a large moveable crane, or a large building on rails to move the next payload into place for securing. It would be impressive if this could be done.
Most of all though, this begs the question, 'Why would this be needed?' What satellites need to be blasted off in that much of a hurry? It is not like there isn't capacity without rushing things.
A couple things come to mind.
- Civilian Human and Cargo flights
- Military transport
In the end, after I think through all of this, it does sound like a pretty cool idea if you were in charge of say a Nation States nations defense system...What next? A portable rocket lander and refueler?
(Score: 0) by Anonymous Coward on Monday January 04 2021, @10:31AM
Expendable launch towers.
(Score: 3, Interesting) by PiMuNu on Monday January 04 2021, @10:44AM
> 'Why would this be needed?'
More likely because super heavy is... super heavy... and the legs are prohibitively expensive in terms of mass.
The super heavy dry mass is 280 tonnes, which is quite a lot. Think great big RSJs to support all that mass.
https://en.wikipedia.org/wiki/SpaceX_Starship#Super_Heavy [wikipedia.org]
(Score: 3, Insightful) by fakefuck39 on Monday January 04 2021, @10:54AM (14 children)
Musk's ambition is always just that though. Just like in Reagan's head we had star wars space lasers, in Musk's mind his car is fully autonomous, and he'll be able to refuel in an hour. But then pesky reality in the form of a new construction zone or grey-dressed small pedestrian hits.
The rocket is under crazy stress during takeoff and landing. Whatever is in Musk's head is cool dreams a hundred years away. In reality, you don't strap yourself to a stick of dynamite until it undergoes a very thorough, multi-day inspection.
The idea is great - why take the heavy landing gear with you and all the extra fuel needed to lift it and land it, if you can just catch the rocket on the ground. But I don't see that speeding up relaunch times, because the thing's gonna need some major inspection, and that's what is holding up relaunch times - not refueling or reloading.
(Score: 1, Touché) by Anonymous Coward on Monday January 04 2021, @11:09AM (1 child)
On the other hand, maybe the far out goal is the point?
Like, he wants to progress the status quo, and deliberately sets his target on "almost-possible" instead of focusing on the incremental upgrade?
Peppered with a healthy dose of showmanship and media strategy, ofcource.
(Score: 0, Offtopic) by fakefuck39 on Monday January 04 2021, @11:41AM
Ok, if the longterm goal is to improve the site via coding a better spam filter, I can see that. But I'm going to guess with a site that has maybe 100 active users, that's a misguided goal, and an annoying one. It's one, maybe two autistic people with a fixation issue. The easier fix would be for them to just stop, until such a time the userbase grows to reddit-size. And at that point soylent likely just won't allow AC postings.
I think with showmanship and strategy, you're giving the guy too much credit - the simple answer is usually the real answer. He has some kind of a fixation thing going, probably from too many stimulants or some kind of an autism thing, and a lot of free time on his hands due to lack of real human contact. It makes this site his life, where for the rest of us it's just a news aggregator - like a tv on in the background.
If there was showmanship or any kind of a strategy, the comments would be smart humor (which has nothing to do with offensive or not). The spam so far falls either in the category "i'll take what you said and reply like i said it about you" and very basic one-liner name calling. Which is fine, if he was creative - it's the repetitive thing that's annoying.
(Score: 0) by Anonymous Coward on Monday January 04 2021, @11:29AM (6 children)
One if the major design goals for Starship/Superheavy is that they won't require a major inspection and refit after every flight, but after around ten flights when the engines need to be rebuilt. The Falcon 9 and Dragon have already raised the bar on fast turnaround by being flight ready to fly again in a few days and this is the next logical step. While he won't achieve it on the first model, or likely even the tenth, just like landing the Falcon 9 he'll get there one step at a time.
(Score: 2) by fakefuck39 on Monday January 04 2021, @11:44AM (5 children)
Oh yeah, I absolutely get the end goal here. I'm just saying like with the self driving cars, it's much, much further away - probably not in his lifetime. What is realistic is maybe a 1-day turnaround with a whole team of inspectors. If he tries to do it sooner, the first explosion will put a dead stop to it, and over all the launches, there will be one for no other reason than "shit happens" when you sit on a firecracker.
(Score: 0) by Anonymous Coward on Monday January 04 2021, @09:40PM (4 children)
We don't disassemble a passenger jet between each flight. We just glance at the outside, looking for obvious problems like flat tires and cracked windows.
One of the many reasons for switching to methane fuel was to avoid carbon deposits in the engines. This means the engines can be run again without cleaning.
(Score: 2) by fakefuck39 on Monday January 04 2021, @10:33PM (3 children)
>We don't disassemble a passenger jet between each flight
correct. because if you send a passenger jet at mach10 like a rocket goes, there wouldn't be anything left to disassemble, from the stress of air friction, and acceleration, and burning of propellant. any more bright observations sparky?
(Score: 1, Interesting) by Anonymous Coward on Monday January 04 2021, @11:21PM
Sparky here, and I articulate myself poorly. Read what I mean, not what I write.
So what you seem to be saying is, since a passenger jet is so well designed and properly engineered for the task it's doing, and since we've been doing that task with them for so long, we've got a very firm and solid understanding of all the variables involved and are able to return them to service speedily, with a minimum of downtime.
Why, by everything on heaven and earth, do you take the position that reaching the same situation with rocketry is such an impossibility? Less than a decade ago, 'someone' could've made the argument that flying a first-stage rocket booster back to earth and landing it on a ship at sea was effectively impossible, and anyone pointing out that we already do somewhat-similar things in somewhat-related fields may even have been given a scalding rebuke and snarkily had more bright observations requested.
Today, here and now, if we could track down this hypothetical someone, we'd need to snap a picture of them for the dictionary, because they look like a fucking ass in hindsight.
The first airplane flew a few minutes and a few hundred feet. Now they break the sound barrier. The first rockets were un-aimed, un-manned and horrifically unreliable. Now we send payloads to orbit and land the first stage on a ship, upright and under power, like the best movie-magic couldn't have created the illusion of in the 60's, and then re-use it. Shit changes. Engineering improves. We will fly re-usable rockets with less than twenty-four hours downtime; It's only a matter of when.
Any more bright observations, sparky?
(Score: 2) by takyon on Monday January 04 2021, @11:27PM
The obvious thing for SpaceX to do is to launch Starlink satellites with the same Starship and booster repeatedly. They have thousands more satellites to launch. They can save a lot of money and prove that Starship can be launched repeatedly without refurbishment, or at least show how often it can be relaunched until it blows up. The FCC has given them until 2024-2027 to launch most of the satellites, so there's no rush to catch boosters out of the air.
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(Score: 0) by Anonymous Coward on Tuesday January 05 2021, @03:03AM
You sound like a whiny small person with no imagination.
(Score: 0) by Anonymous Coward on Monday January 04 2021, @01:51PM
If he thinks that he's a moron. We're nowhere near the point where 1 hour is realistic. Sure, it might take that kind of time to physically fill the rocket, but what about the time it takes to inspect for damage? Rocket fuel tends to be rather volatile and it doesn't take much in terms of damage to lead to an explosion. Best case scenario being that a bunch of expensive gear gets blown up, worst case you have deaths involved. The space shuttles we lost were both over relatively small amounts of damage to an inconvenient spot.
(Score: 2) by takyon on Monday January 04 2021, @07:37PM
Musk/SpaceX have crazy ideas and discard or shelve them as needed. They pursued full reusability for Falcon 9, but abandoned that to focus on fully reusable Starship. The Interplanetary Transport System (ITS) was going to be 12 meters wide, Starship got scaled down to 9 meters, but Musk tweeted that he wanted to scale it back up to 18 meters (more feasible after switching from carbon fiber to stainless steel, probably).
They do want turnaround of less than a day. Less than an hour is new, because they were talking about something like 6 hours before for the booster (up to 4 flights a day). The point of relaunching it so fast is to send up Starship fuel tankers to refuel the first Starship launched.
Here's the down to Earth solution: just build more launch mounts, pads, and boosters. Have them ready to go all around the same time so that they can refuel the primary Starship. Don't bother with the tower arm, and land the boosters on a pad instead of a launch mount.
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(Score: 1) by khallow on Monday January 04 2021, @07:58PM (2 children)
When's the last time you inspected your car? Gas or electric, the car has a lot of energy content. The thing about multi-day inspections also is that they don't add much in the way of reliability and can create their own risks.
(Score: 2) by fakefuck39 on Monday January 04 2021, @08:19PM (1 child)
talk about apples to spec of salt comparison here. a car has flamable material. it does not undergo the stress of a space rocket, it does not have an afterburner exploding to propel you forward.
so why would I inspect my car the same way I'd inspect a rocket? it's not a rocket.
>The thing about multi-day inspections also is that they don't add much in the way of reliability and can create their own risks.
I have no idea what that's supposed to mean. it's simply false.
(Score: 1) by khallow on Tuesday January 05 2021, @05:59AM
So does a rocket. And the quantity of energy in a car is equivalent to several sticks of dynamite - be it gas or electric. When you drive in a car, you really do strap yourself to several sticks of dynamite.
You can end up just as dead in a car as a rocket, and vastly more people are killed in cars than rockets. Afterburners don't explode and the rockets we use to get to space don't have afterburners.
If you have no idea, then it can never be simply anything.
Here, there are several problems with the idea of several day inspections after every launch. First, what can you find in several days of inspections that you can't find with an hour or two inspection? Keep in mind that the rocket has already passed the most serious test of its performance - it's already successfully flown with detailed telemetry of the performance of the rocket stage and every significant component on it.
Second, it depends on what sort of inspection you do, but if you open up a rocket to inspect what's inside it, then you're introducing new risks. Did the inspectors put that complex rocket back together right? Even just parking the vehicle somewhere for a few weeks introduces risk of damage from things accidentally bumping it, getting dropped, and such. With a quick, non-intrusive inspection, you know that the rocket is nearly going to be what already successfully launched.
The catch is that there's some parts that probably will have to be cleaned or replaced every launch. For example, with any sort of hydocarbon fuel, some coking of the ignition chamber and exhaust nozzle is inevitable. Some parts may even need to be replaced after each burn due to heat damage. For example, if you have to open up the rocket engine anyway to replace nozzle components, then it improves somewhat the cost/benefit of more detailed and intrusive inspection. Certainly, the payload will need to be replaced with new ones. Even if you reuse the same upper stages, they'll still need to be reattached.
Finally, we have numerous examples of what happens when we get too careful. There are various dysfunctions that creep in when you're too careful and slow with one part, and then have to rush everything else because the launch has to happen. Reducing risk in one place often results in higher risks spilling out elsewhere.
(Score: 3, Interesting) by takyon on Monday January 04 2021, @07:42PM
I don't think they want to use a Super Heavy booster for point-to-point transport of military [parabolicarc.com] or air passengers. They would just use a Starship by itself, in a suborbital flight.
The rush to reuse boosters is for sending up Starship fuel tankers to refuel a single Starship. Probably not needed for anything up to GEO, but desired/required for the Moon, Mars, Jupiter, Pluto, etc.
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(Score: 1) by TommyJ on Tuesday January 05 2021, @12:48PM
I understand what you mean. But you will probably be very surprised when you find out that mobile spaceports have existed for a long time. Yes, they are still being used to launch small rockets. Like those on which observation satellites are displayed, and so on. Something like this https://www.skyrora.com/blog/press. [skyrora.com] I don't think it will be a problem to make something mobile when needed in the 21st century.
(Score: 2) by Runaway1956 on Monday January 04 2021, @01:51PM (4 children)
I would want the legs on it, so that it can stand freely. Without legs, you lose options. A mission goes south, you can't get into orbit, and you can't get back to the tower, the mission is a loss, along with everything and everyone aboard? That makes no sense. With legs, no matter how badly the mission has gone wrong, you just might set down in Alabama, or South Carolina, or somewhere.
No, I'm not stupid enough to think the legs might rescue every mission that might go wrong, if that's what you're thinking. But the legs might be the thing that saves a life or twenty, so why not engineer around them from the start?
After the super heavy has completed a thousand missions successfully, you might start to consider doing away with them.
“I have become friends with many school shooters” - Tampon Tim Walz
(Score: 1, Insightful) by Anonymous Coward on Monday January 04 2021, @01:55PM (1 child)
Even without legs, you can still set the thing down, it's just that there's more damage. It's probably not a bad bet as most of the time, things should work out the way that you want to and in the rare case where things go sideways, the damage probably the least of your concerns. Even with landing gear, planes do occasionally get set down without the landing gear down for various reasons.
(Score: 3, Insightful) by Runaway1956 on Monday January 04 2021, @02:14PM
I understand your point. But, let's remember that any damage down there among the parts in close proximity to the ground tend to involve the rocket engines themselves, and the plumbing serving the engines. That is, there's a whole lot of potentially explosive material in the damage zone.
“I have become friends with many school shooters” - Tampon Tim Walz
(Score: 2) by r1348 on Monday January 04 2021, @02:55PM
The plan is to land this way only the first stage of Starship, which will have no people on.
I assume that an abort scenario would have stage separation built it.
(Score: 2) by Immerman on Monday January 04 2021, @04:14PM
I appreciate the sentiment, but I'm not sure you're thinking things through all the way. Two things:
1) SuperHeavy will NEVER land with people on board. Passengers will all be on Starship, which will be able to separate and land using it's versatile legs designed to be able to land on uneven surfaces on other planets.
2) How would a mission go south in a way that would prohibit a return to the landing pad, but still leave the option of safely landing somewhere else?
I mean, the thing is going to have 30+ engines, and sounds like it will only need 2 to get off the ground, much less land. Massive redundancy and fault tolerance has been an explicit design goal for Starship + Superheavy from the moment it was first revealed as a long-term concept.
So long as they're not losing propellant or hydraulic fluid, a separation and turnaround is always an option. And if they *are* losing either, they're not going to want to bring that massive, poorly-controlled bomb anywhere close to land - a huge part of the reason they they launch over the ocean is so that they don't put people at risk in case of a major failure.
Heck, for that matter, lets look at the flights of Falcon 9 as a likely good reference for mission profiles - out of all the flights they've launched, how many were scheduled to attempt a landing, but weren't able to make it to the vicinity of the landing pad? Zero by my count. Assuming Starship is no worse once mature, you're talking about including a massively heavy mission-limiting redundant safety system that will be used in less than 1% of missions.
(Score: 1, Interesting) by Anonymous Coward on Monday January 04 2021, @02:15PM (1 child)
Maybe like this?
Park the gird fin close to the tower against the rocket so it won't be in the way. Put the 2 perpendicular fins full out in a vertical position so they can take the most vertical load. Manouver the rocket down into 2 V-shaped catchers for the extended fins. (Make is a 2d V so it centers the rocket in in/out and side/side from the tower.) (Think hanging up an ancient telephone with a separate receiver.)
That seems unlikely unless the rocket structure is not strong enough to be captured from the bottom without tank pressure?
I'm sticking with my favorite:
There are already hard points at the bottom which carry thru in the structure sufficiently to support the whole, fueled rocket for launch. Add four pop-out landing stubs. Build a water curtained, raised landing ring with four landing pads to capture the stubs. Place four servo arms above the ring to reach down and grab the stubs after the flame front passes. Transition the control system to let the arms control lateral giving the engines more freedom to control vertical to zero velocity when the stubs meet the pads. (Perhaps engines make a net small force up and the arms push down to the pads?) Then shutdown and let the arms hold down until someting more permanent can be done.
I'd bet they do something on a separate landing area away from the launch equipment as an intermediate step until someting is reliable.
So who is going to go install the system on Mars for the first landing?
(Score: 2) by takyon on Monday January 04 2021, @07:17PM
I don't think there will ever be a Super Heavy booster on Mars (which would require it to be built there). They will just refill a Starship and launch it by itself. But Mars will become a graveyard of Starships since they will be too cheap to warrant return to Earth. They could even be disassembled on site for materials.
Losing a launch site is a potential disadvantage of the rocket arm plan.
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