arstechnica.com/space/2024/05/surviving-reentry-is-the-key-goal-for-spacexs-fourth-starship-test-flight/
Surviving reentry is the key goal for SpaceX’s fourth Starship test flight
Yeah, re-entry is fun and important for far off goals, but consistently getting 100 Tons to orbit with a reusable first stage is revolutionary for the satellite industry
I think the first thing they should do is put not one but two D8 cats on the moon.
What's really revolutionary, and the goal of Starship, is getting 100t payload to the surface of Mars, not just to TMI.
NASA can presently do 1t payload to the surface of Mars. They are still struggling to extend that to 6-8 ton, the bare minimum for sending crew and returning them to Mars orbit.
Isn't it just Leo?
The "O" in "LEO" is "Orbit."
I don’t know, but even still “Just LEO” is the most important and utilized orbit at the moment and into the near future, and 100 Tons in one launch is insane
Firstly, being able to put 100 tonnes into LEO alone is inherently transformative for all spaceflight, including the satellite industry. Especially being able to do so extremely cost effectively. That's an "Apollo Program" enabling level of capability, and it is indeed a big deal. Yes, it will be used extensively for delivering satellites to LEO, but it's also perfectly suitable for getting satellites elsewhere quite easily just using a kick stage. If you can put 100 tonnes into LEO you can have whatever fraction of that 100 tonnes be some amount of propellant and a rocket stage to be able to get where you want to go, whether that's GEO, the Moon, Mars, Jupiter, or what-have-you. The Space Shuttle, for example, launched the Ulysses, Magellan, and Galileo spacecraft to heliocentric orbit, Venus, and Jupiter, respectively, using just solid fueled kick stages and a much smaller LEO payload capability.
Secondly, Starship shouldn't be viewed as just another launch vehicle, it is properly an entry into a new kind of launch infrastructure relying on orbital propellant depots. Today the root of every "tree" of space launch is generally a single launch from the surface of the Earth, everything else is staging and shedding layers down from that origination. With orbital assembly you can change that characteristic, and with orbital propellant depots you can utterly transform it. Propellant depots mean the start of launch infrastructure on orbit. Instead of just one launch from the ground, you can have another "launch" occurring on orbit after fueling from a depot, and that's wholly transformative.
That means, for example, that you can deliver payload anywhere by using refuellable stages or space tugs. To modify the above example, imagine you have a 100 tonne satellite you want to deliver not just to LEO but to GEO, or lunar orbit, or the Earth-Sun L2 point, or elsewhere. There are lots of ways to achieve that. You launch the payload with a Starship, then maybe the Starship refuels at a propellant depot then delivers its payload to a desired final orbit before returning. Or perhaps the Starship stage hands off the payload to a space tug that refuels and then does the work of final delivery. Or the payload itself may have its own propulsion system that can be refueled and do the work of taking itself to its desired destination.
There are so many options that open up with propellant depot capability that it fundamentally changes the nature of the game. There are going to be ways to make use of these capabilities that nobody has even thought of yet. But overall it's just going to make delivering payload from Earth to anywhere vastly easier.
I've always felt that the most immediate shift we'll see from Starship is a heretofore unknown flexibility in satellite design. Hubble-scale projects no longer need to be a once-per-decades endeavor when you can literally design something that large (or, really, a great deal larger) by default.
We're already seeing it. There are two or three entire space stations in development which are designed to fill Starship's 9 meter hull.
This really is the sauce. I can imagine setting up orbital ship manufacturing where we build ships in orbit many times larger than what is practically possible to make on the surface and launch into space.
LEO is over halfway to Mar, energy-wise, and energy is everything in orbit.
The system should also be providing refueling, which will allow Starship to go well beyond LEO. We could have 100 tons to orbit, refuel, and then take it across the solar system for relatively low cost.
Surviving the return trip is kind of important.
Only for squishy humans who want to return to earth. 100 Tons to orbit without reuse is still a huge deal if they can do it consistently.
Puny humans! Morbo would survive just fine!
As I remember, the bay door didn't properly open either, so at least some problems did happen on the way up.
It was also stuck open during descent.
This is the first I've heard of this. May I ask, where did you get this information?
I'll see if I can find the YouTube video in a bit but it's visible and extremely obvious on the stream from inside the rocket.
Agree, extremely obvious, once you realize, what happens. Unfortunately my mind did not process the evidence during the live stream.
You could see sunlight inside the cargo bay after the door test was marked as concluded and before reentry.
Even with working RCS, would it even be possible to keep the attitude under control with a door stuck ajar?
All in all, surviving the stage sep last time was a big step forward, but the ship reached space with some very serious damage, and I guess there are multiple issues to be sorted out before next time.
It's a sliding cover over a small slot (they call it the "pez dispenser", for deploying lots of Starlink satellites), not a big swinging bay door like on the Shuttle.
The door doesn’t swing out, it slides to the side, so it would leave a gap on the lee side of the ship. It wouldn’t be ideal but it likely wouldn’t be a problem.
It opened just didn't properly close. In any case, a bay door is one of the simpler engineering problems
This is the engineering problem that will end the Starship program. Calling it.
Yeah, honestly it seems like they should be shifting focus away from reentry to focus on the moon lander design and functions. They actually have a contact and a rough timeline for that, where as there's no real deadline for solving reentry problems.
Luckily not an issue for Starship HLS, the lander in particular, although I'm sure they'd prefer if they didn't have to expend the "10-ish" fuel tanker flights supporting it. OTOH, if they don't try to get them back they could deliver more fuel up-mass, couldn't they?
I personally wonder what happens to that 10-ish figure, given that Starship HLS will absolutely not be using the Block 1 design (where the 10 tanker figure comes from) and probably won't even be a Block 2 vehicle. What happens to the tanker count when each flight can bring up 200 tons of fuel?
Given that the number of refills will without question be lessened, I assume that also impacts how long it takes to refuel, which in turn means less boil off, potentially meaning even fewer refills.
Right now, SpaceX starbase general manager quoted 15 and that's why they need to launch from both TX and KSC/CCAFS. I'd also presume that number is using the modified design they clearly are shifting to ASAP.
"We need two launch areas for us to be able to meet our manifest," Lueders said. "Just a single (Moon) landing requires 15 tanker launches, and they need to be done within a certain period of time."
What was the original claim, 4 or 8?
15 is what was bid for the contract, but they were aiming for 8. They wound up consuming all of their margin with extra mass on Starship, but got some of it back with engine improvements... the final number is still in flux afaik.
That's with the next upcoming version of Starship. Probably not ready for 2026/7.
Wonder when they’ll just launch an automated fueling depot and make autonomous trips to drop off fuel in the days/weeks leading up to launch.
Wishful thinking doesn’t change the basic math. It will need an insane number of launches. It’s a shitty system.
Go ahead and name a better one, or any system that has a realistic chance of building a moon base.
Apollo was better all things considered. It’s half a century old.
SLS is also better. You know - the rocket that will take astronauts to the moon. Unlike starship which is only going to be used as a lander (if that, I doubt it will ever make it).
That is a spicy take, we'll see how that looks by the end of the decade.
Depends on how much useful cargo it can bring to the Moon.
If it takes 15 tanker launches to bring 100 tons of cargo to the Moon, that's actually awesome.
If it's 10 tons, that sucks.
Is it though? Starraker was designed in the 70s to take 100 tons into orbit. Plus this Starship heap has taken zero tons anywhere and is yet to complete a flight.
Taking 100 tons to the surface of the Moon would be awesome. With that capacity we could be building telescopes on the Moon.
Anyhow... chemical rockets are great for bringing stuff to LEO, and we can bring heavy stuff to LEO. But I think it is obvious we need ion, plasma, nuclear engines to transport stuff from LEO to anywhere else.
HLS specifically is not bringing 100 tons to the moon. I even wonder how much cargo can actually be lowered through the airlock/lift.
Point still stands. Efficiency heavily depends on the mass of useful cargo delivered to Moon.
The valid metric is cost. Assume, they already have tanker reuse, they can certainly do a tanker flight for $30 million. With 15 flights, that's $450 million. With that they can land crew and quite significant cargo. With a pure cargo flight, no return, it would be 100t landed.
Much more likely $10-15 million. With $2 million as Elons stretch goal. $10 million make the tanker flights just $150 million, about the cost of just 1 of 4 RS-25 engines on SLS.
How about StarShip brings 100 tons of cargo to orbit. Then ion engine slowly pushes cargo to the Moon, small chemical rocket lands cargo on Moon.
It would take more time, but hey that's just for cargo... it can travel for months, so who cares.
This would be very cost effective, and we could build some big ass telescopes on Moon. Even have astronauts service them as needed.
It is not in the line of how SpaceX works. If they have Starship ready for external customers and all of this would be customer payload, sure, why not? But IMO not as a SpaceX mission.
It’s a shitty system.
For the understood mandate of retreading Apollo, there's probably no denying this. But SpaceX got the contract for two very good reasons:
- They were already going to make the vehicle with or without any external incentive, and were already well into the process—to contrast starkly with the alternatives.
- They were the only option NASA's Artemis budget could cover, literally.
With that having been said, the goal of Artemis is to maintain a presence there, and one doesn't get to pretend that a craft that can barely bring down a couple of astronauts is going to enable that. It's a near certainty that Artemis would run out of steam, both financially and popularly, pretty much starting with the first successful landing, if the most meaningful accomplishment of said landings was boots and flags.
Starship HLS was going to be required, posthaste. And as some folks are happy to point out, the math quite simply stipulates that Starship's system is how it's going to be done. Even if somebody other than SpaceX tried their hand at it.
IIRC, the block 2 and block 3 design iterations were a response to the ballooning number of refueling flights required for HLS. Some people were speculating it would be as high as 20 flights without a change, and boil off might become a significant issue eventually
Block 2 was already a thing before then and was originally focused on optimizations on both the ship and booster in response to performance improvements on Raptor. (Which is why it’s likely to phase out V1 at the end of this year/start of next year)
Which is why it’s likely to phase out V1 at the end of this year/start of next year
More than merely likely. According to NSF (or WAI—can't remember which), they're already done with V1 prototype manufacture and we won't see new Starships of that type.
I suppose Block 3's advent will depend on the status of Raptor V3. It feels like a certainty that by the time HLS is actually needed (Orion-related delays already push this to an optimistic end-of-2026), Block 3 will be the new norm. Though I also feel that HLS itself will not need Block 3's capacity... or its height.
Surviving reentry is the key goal for SpaceX’s fourth Starship test flight
It's not a matter of "if" but "when" they get the procedures and design dialed in. SpaceX is currently the global leader in reusable rocketry. Suppose it takes "10-ish" or "20-ish" attempts to get the reentry and landing procedures figured out. Each launch refines the process and lowers the tolerances.
He's speaking of the number of refuelling launches per each Moon launch, not the amount of launches to get Starship right.
There have been stated flight goals for all four Starship test flights so far. Three out of three have been met. This is the first time I'm not altogether confident they'll meet it.
They've already acknowledged that the tile issue is their biggest challenge. But more than that, there has been nothing to suggest that Ship 29's tile outfitting was somehow a new and improved process. Which means it's likely to lose tiles, particularly along seams, same as with past vehicles.
Which in turn carries implications for IFT4's stated key goal.
Still, it will be fascinating to see how close it gets to splashdown before the signal is lost.
It will help if the ship isn't doing barrel rolls during re-entry next time.
Love that I knew exactly what that was going to be a link to.
Funnily enough, NASA actually uses KSP for essentially doing “napkin sketches” of missions.
https://scifi.radio/2023/01/06/nasa-using-kerbal-space-program-for-virtual-experiments/
He (Doug Ellison) notes that many at NASA use KSP to experiment in ways that their more unforgiving real-world environment wouldn’t allow them to do. In essence, they can do a rough test of the many strange ideas that never quite make it off the ‘sketch on a napkin’. This allows them to save time, money, and manpower while possibly having a little fun with “rocket science” too.
What, you mean the rotisserie chicken method won't be used anymore? Shucks.
I personally feel the elevator music radio won't be nearly as on-point without some active tumbling. Maybe when they reach a cadence of every week or two, they'll shift to space ambient or something.
They need to stop showing these ships 2001: A Space Odyssey right before launch.
I’ll be happy to get more onboard HD footage.
That friggin' plasma plume was beautiful as hell, wasn't it?
The reentry failure on the last flight was an attitude control issue. The live reeentry footage was stunning, I hope to see more of it on the next flight.
I still haven't heard about a cause. Speculation pointed at the valves possibly being frozen over. It struck me as similar to the time when they lost a Falcon 9 first stage because they ran out of fuel something like 20 feet from the drone ship.
Weren’t they just using kerosene as hydraulic fluid in an open system at that point to drive the grid fins ?
Can you explain what you mean by "suicide burn" - is it just a more aggressive speed in and barely stopping in time?
Colloquial term SpaceX uses to refer to how the Falcon 9 handles its landings. Basically means they stop on a dime, like you said. It's the most efficient way of doing it, so I guess they figured that as long as it's theoretically possible, that was going to be the goal, no pussyfooting.
Falcon 9 also has a high enough thrust to weight ratio (when its fuel is nearly empty during landing) that even with a single engine burning at minimum throttle, its thrust is too high to hover. So they're forced to do the hoverslam/suicide burn. It's also most efficient, which is a nice bonus, but it's not something they have to do with superheavy.
It's more than that- the F9 does not have hover capability. Even on one merlin at minimum thrust, at landing mass the thrust to weight cannot reach 1:1 or lower, so there's simply no way to do a gentle throttle controlled descent at all. You just have to fire so that at the end of your burn you're at exactly both zero altitude and zero speed (well, the legs give some margin, but it ain't much). Too long and you'll shoot right up again and crash, too short and you'll be too fast at landing and plow into the barge, hit the burn too high and you'll do an uncontrolled drop onto the barge or pad. Throttling up can compensate for starting the burn a little late, but in most scenarios there's zero margin on timing and controlling that burn. A throttle controlled descent gives you a lot of margin for error and room for precision, and SpaceX very well may have done that if the Merlin could throttle deeply enough to do it.
I think it is still a throttle controlled descent in some respects: overshooting the ignition time a little bit lets them run the engine at greater than minimum thrust and either increase or decrease it from there to fine tune it for touchdown.
Suicide Burn is a colloquial term from the Kerbal Space Program community for any landing burn where the t/w ratio is significantly above 1. SpaceX marketed it as Hover Slam.
OK, let's hold on a second here. The attitude control issue pretty much ensured failure on re-entry. However, let's be very clear, we don't know whether the vehicle would have survived re-entry if it had been able to maintain attitude control. Hopefully we'll find that out on this test flight, but it remains an open question.
Heat tiles really are the bane of spaceflight aren't they. We really need to find some way to make heat-resistant spacecraft that doesn't require bolting or gluing shit on their belly.
It's the reusability that really hurts. They will need to inspect the entire tile assembly after every launch before they send it back up. It's no wonder they were initially thinking about a perspiring hull. Maybe that will even be where it all ultimately leads.
They will need to inspect the entire tile assembly after every launch before they send it back up.
Oh god oh no please no
Although, I do remember that at some point NASA developed a technology to quickly xray heat tiles for damage. A few years before the STS was retired. Fate has an irony.
The shuttle's tiles were quite robust even from day one. Of course in exchange, they were also an almighty pain to maintain. The scary thing is that they understood quite well that any single missing tile in the wrong place (and that was really the vast majority of the vehicle's belly) would have been a guaranteed disaster.
'They've already acknowledged that the tile issue is their biggest challenge.'
I don't think they have. Rapid reusability is probably harder. The shuttle managed 135 flights using tiles to deal with re-entry and yes, this is a different system, but it's still tiles dealing with re-entry.
The shuttle managed 135 flights using tiles to deal with re-entry
That's actually what makes me confident that they will eventually get this sorted out. Absolute worst case scenario is that they end up having to use a tile application process similar to the shuttle's. What's clear is that their current system needs adjustments, and the tiles themselves need to be made more robust. Those haven't happened yet. Nobody outside SpaceX knows what they intend to try in order to address these issues, but for now, they seem content just to see how well a vehicle handles the current system, including likely missing tiles.
I think they will try it and see, look to see which tiles fall off and then fix those ones more robustly. The joy of launching a lot of rockets is they can afford to build up that knowledge steadily, it doesn't have to work 100% from the start. I don't imagine SpaceX will ever settle for the shuttle process, it took too long and was too expensive - they'll keep working on it until they have something rapidly reuseable and with the starlink money they should have the funds to do that.
The joy of launching a lot of rockets
There's a rumor that future FAA licenses will come in sets. That would be nice. Thus far, SpaceX has been calculatingly tailoring their IFT readiness to the FAA's own readiness, and taking advantage of the considerable free time to work on whatever they can on the ground. It's the reason why licenses have always arrived less than 24 hours before a launch. But nothing is more important than that flight data, and you'd better believe SpaceX would be happy to take advantage of an improved cadence.
Which goals did they meet?
IFT-1: Clear the tower
IFT-2: Stage separation
IFT-3: Nominal trajectory after ascent
In order:
Clearing the tower without blowing up.
Stage separation. (I was really surprised this went off without a hitch. Booster's fate notwithstanding.)
Second stage full burn and near-orbital velocity. (Technically, they mainly wanted to get further than IFT2.)
There may be some people laser-focusing on mission objectives or the overall flight plan. I would direct them to the thread's topic, wherein the "key goal" is underscored. I suspect SpaceX themselves do not feel that they have failed if every single flight plan for a given prototype isn't met. And they have the unprecedented cornering of the private space industry to back them up on that.
Even though Starship development still has a lot of work left remaining to get to full operational capability of all of the desired functionality it's worth pointing out that if this were an "old fashioned" rocket they would be done already. They've already demonstrated the ability to get to orbit with a heavy lift launcher, which is a remarkable capability all on its own. That they're also shooting for full reusability and orbital propellant transfer is so above and beyond it's ridiculous. But it seems like they'll pull it off eventually, it's just a question of how long it'll take and how expensive it'll be to get there.
This is something that gets ignored because of the landing attempt failures.
Strip off all the tiles, wings, grid fins, extra fuel, and extra tech needed for landing, and Starship+Superheavy is the most powerful rocket ever built, and the cheapest super heavy lift vehicle, closer in price to a falcon heavy launch than other rockets in the same lift class. It may actually be cheaper than a falcon heavy launch
and how expensive it'll be to get there.
Aside from their history of proving the doubters wrong, another reason I have confidence in SpaceX is that this money really doesn't seem to be an issue for Starship development. The F9 platform is SO damn successful that they have all these contracts and barely need to build any new engines or boosters because the reusability is so high. Plus with Starlink they are really filling up the cash reserves. Obviously there is some budget limit but they have also optimised the Starship manufacturing process to be as cost effective as possible in the long run. They can just keep churning out these prototypes and run as many test flights as they can get ready (along with FAA approval).
Very different to the early days where they literally emptied the cash reserves just to get Falcon 1 to orbit.
it's worth pointing out that if this were an "old fashioned" rocket they would be done already.
Tumbling out of control will definitely mark the "old fashioned" rocket as not done.
Old fashioned rockets typically let all of their stages tumble out of control and re-enter.
Not the last stage, though.. you can't deploy your payload if you don't have control over it.
Also, the other stages complete the preplanned flight path.. control is not needed anymore.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| CCAFS | Cape Canaveral Air Force Station |
| CST | (Boeing) Crew Space Transportation capsules |
| Central Standard Time (UTC-6) | |
| ESA | European Space Agency |
| EUS | Exploration Upper Stage |
| FAA | Federal Aviation Administration |
| GAO | (US) Government Accountability Office |
| GEO | Geostationary Earth Orbit (35786km) |
| GSE | Ground Support Equipment |
| GTO | Geosynchronous Transfer Orbit |
| HLS | Human Landing System (Artemis) |
| Isp | Specific impulse (as explained by Scott Manley on YouTube) |
| Internet Service Provider | |
| JWST | James Webb infra-red Space Telescope |
| KSC | Kennedy Space Center, Florida |
| KSP | Kerbal Space Program, the rocketry simulator |
| L2 | Lagrange Point 2 (Sixty Symbols video explanation) |
| Paywalled section of the NasaSpaceFlight forum | |
| LEO | Low Earth Orbit (180-2000km) |
| Law Enforcement Officer (most often mentioned during transport operations) | |
| LH2 | Liquid Hydrogen |
| LLO | Low Lunar Orbit (below 100km) |
| LOX | Liquid Oxygen |
| NDA | Non-Disclosure Agreement |
| NRHO | Near-Rectilinear Halo Orbit |
| NSF | NasaSpaceFlight forum |
| National Science Foundation | |
| RCS | Reaction Control System |
| RUD | Rapid Unplanned Disassembly |
| Rapid Unscheduled Disassembly | |
| Rapid Unintended Disassembly | |
| SLS | Space Launch System heavy-lift |
| SRB | Solid Rocket Booster |
| SSME | Space Shuttle Main Engine |
| STS | Space Transportation System (Shuttle) |
| TLI | Trans-Lunar Injection maneuver |
| TMI | Trans-Mars Injection maneuver |
| ULA | United Launch Alliance (Lockheed/Boeing joint venture) |
| Jargon | Definition |
|---|---|
| Raptor | Methane-fueled rocket engine under development by SpaceX |
| Starliner | Boeing commercial crew capsule CST-100 |
| Starlink | SpaceX's world-wide satellite broadband constellation |
| apogee | Highest point in an elliptical orbit around Earth (when the orbiter is slowest) |
| autogenous | (Of a propellant tank) Pressurising the tank using boil-off of the contents, instead of a separate gas like helium |
| hopper | Test article for ground and low-altitude work (eg. Grasshopper) |
| hydrolox | Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer |
| iron waffle | Compact "waffle-iron" aerodynamic control surface, acts as a wing without needing to be as large; also, "grid fin" |
| methalox | Portmanteau: methane fuel, liquid oxygen oxidizer |
| perigee | Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest) |
NOTE: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below.
40 acronyms in this thread; the most compressed thread commented on today has 13 acronyms.
[Thread #10070 for this sub, first seen 22nd May 2024, 00:40]
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Seeing the Reentry glow around Starship on flight 3 was AMAZING with Starlink coverage.
Is there an advance of using liquid methane over liquid hydrogen, or jet fuel? Are there other rockets that have used it?
Liquid hydrogen is a pain in the ass that loves to leak
RP1 (jet fuel) is dirtier. It creates more pollution, but more important for SpaceX and Starship specifically, using Methane means less maintenance since they didn't have to clean soot our of the used engines
Finally, methane can be made on Mars using the CO2 from the atmosphere and mined ice/water, allowing them to make the return fuel in-situ, rather than have to carry it all with them as the way from Earth
China recently launched a methane rocket, and most in-design rockets also use it
Methane is the sweet spot between various factors such as the Isp (a measure of how efficient a certain rocket set up is at using its fuel), engineering considerations such as handling and tank size and of course the option of maybe refueling on Mars at some point. LH2 is a pain to handle and requires larger fuel tanks.
A lot of new rockets use methane. Methane wasn't really used much before. If you are just looking at non-reusable launch on earth, jet fuel is just as good. People had more experience with that so they used that instead. Hydorgen is better for upper stages then jet fuel or methane.
So the reason first stages are switching to methane is because of easier reusability. That's why RocketLab and ULA have picked it for example.
Starship uses methane instead of hydrogen on the second stage because if you look at the whole chain in regards to Mars, methane actually works better and is cheaper.
ULA's Vulcan rocket, whose first stage uses engines from Blue Origin, uses methane. Its first (and so far only) launch was this January.
Is this one still suborbital, or are they actually doing the insertion and deorbit burns this time? I know at the point they got to last time, it’s really just a matter of a little more fuel to finish getting to a full orbital trajectory, but there’s a little more maneuvering and an extra burn necessary to deorbit. Does anyone know if they’re testing that part out here too, or just keeping it simple like last time?
And if it does get through max reentry heating (and makes it all the way down to the water, which I’m guessing it’ll be over?), do they have fuel onboard and plans to do any sort of flip and mock landing, or are they just planning to belly flop for this one?
(Quick note to hopefully head off any rabid fanboys who think I’m being mean by asking a reasonable question…I do know they weren’t trying to get all the way to orbit last time, and I think that was perfectly reasonable. I also think it’s reasonable if that’s their plan this time. I’m just curious what the plan actually is. I’m not saying, implying, or trying to get anyone to infer that the last flight was a failure.)
I believe the flight plan is pretty similar to IFT-3, so no full orbit yet.
Cool! Thanks!
Much better answer than the temporary ban I got from r/elonmusk for asking the same question lol
Do the tiles get much of a baking if they're not doing an orbital braking?
The velocity of the almost orbital trajectory is essentially the same as the almost orbital trajectory the vehicle would experience after a retro burn from orbit prior to atmospheric reentry. In other words, from LEO, you have to slow to sub-orbital (or at least perigee within the atmosphere) in order to come home. It's not like a blazing hot lunar return trajectory with an apogee at lunar orbit. The apogee of the orbital flight and the suborbital flight would be just about the same.
The difference in speed is minimal so while they might see a little less heating it won't be much.
Is this one still suborbital, or are they actually doing the insertion and deorbit burns this time?
They won't attempt full, stable, orbits until they can test and verify upper stage engine relights. IFT-3 did not relight the upper stage engines (due to other issues) and they don't want to be responsible if one gets stuck up there and enters uncontrollably.
its not really suborbital, suborbital implies the orbit intersects the terrain. they did like 180km by 80km, which is not a stable orbit, but its average altitude was above the karmen line, which is how on orbit would normally be defined. its a muddy mess to define but suborbital isnt right. it doesnt become suborbital until after it begins to reenter.
From Wikipedia:
The spacecraft trajectory was suborbital, with a 234 km (145 mi) apogee and −50 km (−31 mi) perigee, although the ship did reach orbital speed.).
The orbit definitely intersected the terrain..
It did have a semi-major axis (and thus orbital energy) sufficient for orbit if their ending trajectory had been less elliptical, so it’s definitely not nothing…but you’re right…it’s also not orbit.
Is this one still suborbital
It's probably easier to think of things in terms of energy and planes. Last flight had oodles of excess energy, and essentially reached "orbit", but followed a parabolic re-entry arc. The next flight, and probably subsequent test flights will likely do the same
Again, I’m not knocking anyone for how they decided to do it. It makes sense, and I know they almost certainly could have been in an actual orbital trajectory if they wanted to. Please read my final paragraph, especially the italicized part. I’m just curious what the plan is. Not every question is an attack.
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1mo
So is the idea to burn RCS the whole time (through reentry) to maintain orientation or is there some sort of physics breaking reaction wheel involved?
At the phase where it broke up in the previous flight, the floopyflops were probably not useful but if it had entered at a stable orientation, minimal if any RCS would probably have been needed until the brakerons could grab air.
They’ll probably use RCS down to about 150,000-200,000 feet. The control surfaces are quite large, so I bet those become effective pretty high up.
This topic is quite exciting and full of possibilities and potential. The future is near!! Hahaha 😆
Because incinerating highly trained geniuses is really bad for PR
My mind immediately went into the gutter upon reading this, and now has cigarette butts, dead leaves, and dirt on it.
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1mo
NASA disagrees with your assessment
Remember this: SpaceX will never reach orbit.
Remember this: Booster reuse will never work.
Remember this: SpaceX will never fly astronauts.
Yeah, I remember past predictions like this.
After Hyperloop, the Boring Company, Tesla's failures, and Solar City, you'll excuse me for doubting the man. Let me know when he proves Tsiolkovsky wrong, m'kay?
Name another car company that grew as much as Tesla in the last 10 years.
Tesla Energy keeps selling the Solar City technology. The Boring company has an operational system and works on expansions.
There was never a Hyperloop company.
Your examples aren't particularly convincing.
Let me know when he proves Tsiolkovsky wrong, m'kay?
Starship HLS doesn't violate the rocket equation, so I have no idea what you are trying to say.
Hyperloop
what about it? Sure, richard Branson misspent money there, but how is it relevant to this conversation? Rochard Branson isn't involved with SpaceX.
Solar City
What about it? it's a bit of a niche product line, sure, and not very competitive. every company has dozens of those.
Tesla's failures
I wish I could fail as much as Tesla.
the Boring Company
What about it? It's a decently successful engineering/research firm.
Frosty, have you taken your meds? You're mighty incoherent.
I take a slightly more optimistic route: Starship will land on the Moon with a human crew, but in like 2030
Musk: we will have routine launches to mars by 2019
Also Musk: it’s 2024 and we’re still trying to leave Earth’s orbit.
elon time, but they’re getting there
They have a 0% success rate with Starship. They can’t prove they can leave orbit even once. How in the hell is that “they’re getting there”?
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If it in fact survives it, it's going to be amazing, but for now all I hope for is that the booster performs its simulated landing without any major issues because what comes next would be super exciting