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Starship is still not understood

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Re: Starship is still not understood

#271

Post by zardo »

panick21_ wrote: post #133
dangerbird2 wrote: post #119

Earlier quoted context omitted.

> That is still a 200-ton to Orbit launcher for the cost of a Falcon 9 or cheaper. If they can't prove rapid reusability for both stages, it's extremely unlikely the cost will be anywhere close to as cheap as current estimates. And if they can't refuel in orbit (which as of now, has only been performed a handful of times with small satellites), Starship will be unable to leave Earth's gravity well.

The current estimate is 2M or maybe 10M. If the first stage is reusable, having a cargo launcher second stage that is none, reusable can be done for 30M. First stage reuse is wall proven already. > Starship will be unable to leave Earth's gravity well. If its not reusable you can use it like any upper stage and it could launch anything anywhere you want. > And if they can't refuel in orbit (which as of now, has only…

> I really think this is overrated in how much of a technology risk this is. Specially if you have enough weight that you can invest in the solution.

Refueling is a schedule risk, maybe the first design will fail to account for something and it will take a couple iterations to get it right. There is zero risk that the problem is unsolvable.

Re: Starship is still not understood

#272

Post by humanwhosits »

ncallaway wrote: post #151
JulianMorrison wrote: post #128

Earlier quoted context omitted.

If they were trying something genuinely new - like falling out of orbit and making a propulsive upright landing of a wingless booster - then some skepticism would be justified. But what's new in Starship?

> But what's new in Starship? The planned recovery mechanism (the aerodynamic fall, with a very late righting maneuver and landing) is still quite new. They've successfully tested it once (which is great!), but the Starship concept really hinges on that being an extremely high reliability maneuver. I would argue that, until SpaceX can demonstrate that landing maneuver is high reliability, that the Starship concept is…

They can take the mass penalty of performing a large re-entry burn to reduce heat-load and land falcon9-style. It would mean _much_ less mass to orbit, but the cost savings of reusing the vehicles would still be there.

Re: Starship is still not understood

#273

Post by giantrobot »

TeMPOraL wrote: post #255
vanattab wrote: post #180

Earlier quoted context omitted.

This. The JWST cost/will cost about 10 billion dollars. The launch costs are negligible.

The JWST costs that much primarily because it's a one-off, which is a consequence of high launch costs. If you drop the launch costs by 100x, this means being able to launch 100x JWSTs for the same price, meaning it makes sense to optimize for production costs instead of reliability - as if one of your telescopes fail, you can always launch/use another. So now it makes sense to focus on using mass-manufactured parts…

> If you drop the launch costs by 100x, this means being able to launch 100x JWSTs for the same price

As the GP pointed out the launch cost of the JWST is a small fraction of the program's overall cost. Launching a hundred JWSTs would mean building a hundred JWSTs and doing so is not cheap. Even with economies of scale producing various components for the hundred JWSTs those all need to be tested and verified. That's an expensive process that doesn't really benefit from economies of scale.

For an instrument the size of JWST you can't just spam launches with the assumption some will fail. It's a giant instrument. A catastrophic failure would see it land mostly intact in a populated area or fill a huge orbit with dangerous debris. Even if it was just non-operational it would not occupy an orbital slot that's unusable by other instruments.

Launch costs are almost always a small portion of overall mission costs. Just because launch costs go down doesn't mean space missions can magically scale up. The goal is to launch useful scientific/commercial instruments or space vehicles. We don't just launch hunks of lead into orbit for funsies. Lower launch costs are nice but they're not going to magically make all space missions cheap or easy.

Re: Starship is still not understood

#274

Post by TeMPOraL »

giantrobot wrote: post #273
TeMPOraL wrote: post #255

Earlier quoted context omitted.

The JWST costs that much primarily because it's a one-off, which is a consequence of high launch costs. If you drop the launch costs by 100x, this means being able to launch 100x JWSTs for the same price, meaning it makes sense to optimize for production costs instead of reliability - as if one of your telescopes fail, you can always launch/use another. So now it makes sense to focus on using mass-manufactured parts…

> If you drop the launch costs by 100x, this means being able to launch 100x JWSTs for the same price As the GP pointed out the launch cost of the JWST is a small fraction of the program's overall cost. Launching a hundred JWSTs would mean building a hundred JWSTs and doing so is not cheap. Even with economies of scale producing various components for the hundred JWSTs those all need to be tested and verified. That's…

> Even with economies of scale producing various components for the hundred JWSTs those all need to be tested and verified. That's an expensive process that doesn't really benefit from economies of scale.

My point is that all those processes are expensive because the final result has to work the first time, because launches are expensive and infrequent. Drop launch costs enough, you don't need so much reliability, so everything across the board suddenly becomes much cheaper. Which then opens many further opportunities to reduce costs.

Re: Starship is still not understood

#275

Post by macintux »

Dylan16807 wrote: post #233
ceejayoz wrote: post #135

Earlier quoted context omitted.

Propulsive landing of an orbital stage is pretty new. (You can make an argument for Soyuz's just-before-landing rockets, but it wouldn't be a fair one.)

> Propulsive landing of an orbital stage is pretty new. It is, but those are largely separate features. Each half of that combo has been done, and combining them doesn't cause any massive engineering conflicts.

No one has, to my knowledge, de-orbited a spacecraft ready to launch again immediately, which is where Musk thinks Starship is headed. That’s a big jump.

Re: Starship is still not understood

#276

Post by Dylan16807 »

macintux wrote: post #275
Dylan16807 wrote: post #233

Earlier quoted context omitted.

> Propulsive landing of an orbital stage is pretty new. It is, but those are largely separate features. Each half of that combo has been done, and combining them doesn't cause any massive engineering conflicts.

No one has, to my knowledge, de-orbited a spacecraft ready to launch again immediately , which is where Musk thinks Starship is headed. That’s a big jump.

That is, yes, but jumping that hurdle doesn't really matter if the landing is propulsive or not.

Re: Starship is still not understood

#277

Post by yk »

Lambdanaut wrote: post #146
yk wrote: post #88

The entire space reporting has the problem that simultaneously there is an established genre of fanboy fawning about space x, which is kinda unconnected to space x actually starting to disrupt space. Right now, it looks like one could save a few billions if Artemis is not green lit a decade ago. However, private launches were still rare at that time, so in absence of a, likely expensive, time machine that's just not…

> star ship does not have a planned launch to orbit yet Starship has a planned launch to orbit in literally a month pending regulatory approval. * source: https://mobile.twitter.com/elonmusk/status/14515814656454942...

They don't plan to circulate the orbit, and instead the plan is to splash down in the Pacific after going 3/4th around the planet. So, I would call that suborbital.

Re: Starship is still not understood

#278

Post by ben_w »

ceejayoz wrote: post #268
ben_w wrote: post #267

Earlier quoted context omitted.

> In other words, the larger the comet, the better. I don’t think so? If you’re bringing in a big one you need more engines to push it into the right orbit to start with, so I think the risk is always things that scale up directly with the comet’s mass, e.g. “the engines are misaligned by $foo degrees”. Also, a pebble in space terms is still a potential city-killer, and no nation in their right mind is going to want…

In the "whoops" scenario (i.e. non-malicious), an engine misalignment would be apparent with enough time to correct. You're a year out. We watch asteroids zing by regularly. The ones we know about have their chances of hitting calculated years or decades out.

Sideways motion is harder to determine than motion towards us; the former needs angular resolution, the latter doppler radar.

And the sort of rock that could shift 67P from a safe to a dangerous path (LEO to 45 degrees one year ahead) would be about 13 metres radius. The Wikipedia citation is 5 years old, so I don’t know what we know today, but in 2016 the estimate was we only knew somewhere around 1.3% of asteroids between 40m and 3.5m diameter (and 0.003% of smaller than that, because things get harder to spot as you get smaller).

Wiki: https://en.wikipedia.org/wiki/Near-Earth_object#Size_distrib...

ArXiv link because the citation in Wikipedia was giving me a server error: https://arxiv.org/pdf/1604.06328.pdf

Re: Starship is still not understood

#279

Post by Sammi »

wildermuthn wrote: post #257
marktangotango wrote: post #248

Earlier quoted context omitted.

Gobi desert doesn't have 1/3 earth gravity.

What are the economic benefits of low gravity? If so, would the moon be more economically valuable than Mars? I’m genuinely curious about the economics of doing more in space than putting up satellites.

I mean obviously you need less energy to move things around. We spend an enormous amount of energy to move things around on earth.

Re: Starship is still not understood

#280

Post by qayxc »

cookingmyserver wrote: post #251
qayxc wrote: post #85

Earlier quoted context omitted.

Exactly. Way too many people seem to ignore the cost of developing and certifying scientific instruments. There's nothing gained from sending 50t of metal to the outer solar system. Scientific instruments are usually purpose-built and while lifting mass restriction can bring down cost, you'd still have to account for redundancy and precision because no one's going to fly out to Jupiter to properly unfold that darn an…

> Way too many people seem to ignore the cost of developing and certifying scientific instruments. It gets ignored because it is a symptom of not being able to cheaply launch probes. You spend all of this time researching and developing a scientific instrument only to make two of them. One to launch the other to go on a diagnostic model (maybe a third for a launch backup). You spread out the cost of development over…

> It gets ignored because it is a symptom of not being able to cheaply launch probes.

Is it, though? Let's do a quick and very superficial analysis of the costs here. Say we want to send a probe the outer solar system, like the moons of Jupiter or the Saturn system.

There are two unique challenges that such probes are faced with:

• on Jupiter, the magnetic field of the planet requires hardened electronics and shielding

• in the Saturn system and beyond, nuclear power is the only option for powering your instruments

Neither of these points are in any way shape or form correlated with launch costs. In fact, in order to get RTGs you need to build, maintain and operate an entire specialised nuclear facility. Alternatively you could use small nuclear reactors, but that may or may not interfere with certain instruments.

The cost of hardening electronics and shielding is also not going away even if launch costs were non-existent. It also doesn't matter much whether you produce 10 or 1000 of such specialised processors - the cost will still be orders of magnitude higher than comparable commodity options.

It's not getting any better if we turn inwards instead and consider Venus or Mercury. Both again pose incredible and unique engineering challenges as do most scientifically interesting targets in the solar system.

How exactly would a cheaper launch cost solve the problem of a Venus sample-return mission? Is it the expensive launch that prevents us from sending an orbiter out to Pluto? How does more and cheaper payload help with getting a probe into the oceans of Europa, Ganymede, or Enceladus? I could go on, but I think you get what I mean.

edit: there's also the human factor that I conveniently left out - every mission requires a staff of people (both scientists and engineers) for the entire mission duration; that cost is also unrelated to launch costs

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