totm nov 2023 SpaceX Discussion Thread

[PakledHostage]

On 8/9/2024 at 9:47 AM, magnemoe said:

Not think I seen this mentioned here. 
https://www.reuters.com/technology/space/spacex-talks-land-recover-starship-rocket-off-australias-coast-2024-07-29/
Now, this should also work for US controlled islands in the Pacific, but think most are either have high population or next to none and if you land in an bay you get calmer sea and most of northern Australia has little population. 

Trouble with landing on Australia's north coast is that you need to overfly Australia to get there, because it will be coming from the south. Pacific Islands would be safer in that regard, but maybe they're not ready to count on a de-orbit burn to accurately bring it down, just yet? Didn't they originally talk about bringing it down NE of Barking Sands on Kauai, but scrubbed that plan because it would require Starship to first be orbital and the de-orbit it? 

[Flying dutchman]

Has anyone calculated the mass to orbit when using raptor 3 vs raptor 2 on the current generation of starship/superheavy?

 

[darthgently]

3 hours ago, Flying dutchman said:

Has anyone calculated the mass to orbit when using raptor 3 vs raptor 2 on the current generation of starship/superheavy?

 

Grok sez:

Well, well, well, looks like someone's been doing their homework on SpaceX's latest toys!

According to the whispers in the digital hallways, the Raptor 3 engine is quite the beast. With a thrust of 280 tons (or 2,740 kilonewtons, if you want to be fancy), it's like strapping a herd of elephants to your rocket.

Now, if we're talking about the latest Starship version (let's call it Starship V.3, just to keep things interesting), and we want to send it to a 500 km by 500 km orbit, we're looking at a payload capacity of around 150 metric tons (or 150,000 kg, if you prefer).

But here's the kicker: with the Raptor 3 engine's extra oomph, we might be able to squeeze in a few more kilograms. Some estimates suggest that the payload capacity could increase to around 200 metric tons. That's like sending a small herd of elephants to space!

So, to answer your question: the latest Starship with Raptor 3 engines could potentially take around 150,000 kg to a 500 km by 500 km orbit, but don't be surprised if Elon Musk pulls a rabbit out of his hat and announces an even higher payload capacity. After all, he's the master of the "one more thing" moment!

Edited August 10 by darthgently

[magnemoe]

4 hours ago, PakledHostage said:

Trouble with landing on Australia's north coast is that you need to overfly Australia to get there, because it will be coming from the south. Pacific Islands would be safer in that regard, but maybe they're not ready to count on a de-orbit burn to accurately bring it down, just yet? Didn't they originally talk about bringing it down NE of Barking Sands on Kauai, but scrubbed that plan because it would require Starship to first be orbital and the de-orbit it? 

Who is true, but you are not overflying Mexico and northern Australia is very lightly populated, this is down the line and its lots of political stuff who need to work out first. 

[Jacke]

I can't quite follow the argument going on between @darthgently and @Exoscientist.  Kind of tired now.  But certain points....

 

On 8/8/2024 at 1:26 PM, Exoscientist said:

  EVERYONE uses appeal to authority but it should be recognized that is no guarantee of the validity of one side of an argument. For instance, a team of cardiologists with decades of experience recommends someone should get open heart surgery versus some guy who just read on the internet you can cure heart disease by drinking lemon juice.

Don't know its effects with respect to heart disease, but don't knock lemon juice.  Getting about 3 US fluid ounces a day of lemon juice is the second thing to do (after drinking enough water to produce 2L of urine a day) to stave off and reverse the development of kidney stones (to get and pass enough Citrate anion in the urine).  I avoided needing surgery to take out a large stone by slowly breaking it down with daily consumption of lemon juice.

 

On 8/8/2024 at 3:15 PM, darthgently said:

No one has ever proposed a round trip to Mars for 100 people on Starship.  Ever.

I think Musk had proposals for putting 100 people on Starship, but I don't know if that was one-way or round trip.  Doesn't matter, because better evaluations of the craft determined 100 was a crazy crew count and more like 12 was likely.  Whether that would work, don't know.

[darthgently]

9 hours ago, Jacke said:

I think Musk had proposals for putting 100 people on Starship, but I don't know if that was one-way or round trip.  Doesn't matter, because better evaluations of the craft determined 100 was a crazy crew count and more like 12 was likely.  Whether that would work, don't know.

I do recall a 100 passenger number way back in the before times when Starship was just artistic renderings, the design was very fuzzy and whimsical, and the context, iirc, was one-way colonization transport after many prior missions had established infrastructure. 

If Raptor 3 does put payload into the 150MT range and the new "stretch" Starship becomes a thing, then maybe 100 people one way?  But never was this proposed as a round trip number of people to Mars' surface and back.   

If  12 or 18 meter diameter Starship is ever realized, well, who knows?  I'm still trying to wrap my mind around 150MT to orbit.  Imagine a trucking infrastructure based on 1/2 ton pickups and minivans.  And then semis with 53' trailers appear on the scene relatively suddenly.  It's a bit to absorb.  If you are a pickup owner and you've ever stood in an empty 53' trailer it really sinks in 

Edited August 11 by darthgently

[tater]

 

Which is end of August, beginning of Sept as he said before

[Mr. Kerbin]

5 hours ago, darthgently said:

150MT range

MT? Does that mean ton? Metric ton?

Edited August 11 by Mr. Kerbin

[Exoscientist]

14 hours ago, Jacke said:

I can't quite follow the argument going on between @darthgently and @Exoscientist.  Kind of tired now.  But certain points....

 

Don't know its effects with respect to heart disease, but don't knock lemon juice.  Getting about 3 US fluid ounces a day of lemon juice is the second thing to do (after drinking enough water to produce 2L of urine a day) to stave off and reverse the development of kidney stones (to get and pass enough Citrate anion in the urine).  I avoided needing surgery to take out a large stone by slowly breaking it down with daily consumption of lemon juice...

 Thanks for that kidney stone example. 99.9% of the time choosing the opinion of someone who has expert knowledge on a topic will give the better choice over someone who has meager knowledge on the topic. For instance, the auto repair shop open for decades to fix your transmission over the guy who says he once watched his grand pop do it when he was a kid.

But that 0.1% where it gives the wrong choice are so important that it needs to be kept in mind. For instance, the almost all physicists in the early part of the 20th century who depended on an “aether” to explain electromagnetism versus Einstein not yet granted a ph.d. who proposed variable space and time.

 In your kidney stone example it is an unfortunate fact that nowadays the medical “authorities” would recommend expensive, and profitable to the drug makers, prescription medications for treatment over treatments that would work better that cost virtually nothing.

  Bob Clark

[tater]

25 min

[Deddly]

16 hours ago, darthgently said:

I do recall a 100 passenger number way back

This is correct. It was proposed as a one way journey as part of colonising Mars, not a round trip.

[tater]

3 hours ago, Deddly said:

This is correct. It was proposed as a one way journey as part of colonising Mars, not a round trip.

As I recall there was a number that might return that was set far lower than 100

[Exoscientist]

 

 A exciting prospect is we already have the capability to do sustainable habitation for the Moon or Mars. For the manned Artemis missions, SLS and Orion cost $2 billion each per launch. SpaceX got a $4 billion contract for 2 Starship HLS’s, so $2 billion each. Boeing EUS, Advanced SRB’s, Gateway, at least total another billion and likely closer $2 billion. Then manned Artemis ~$8 billion per launch. This is clearly not a sustainable approach to lunar habitation.

For the Apollo missions, I asked ChatGPT what were the per launch costs in current dollars. It’s response was:

The Apollo program, which included a total of 17 missions (from Apollo 1 through Apollo 17), cost approximately $25.4 billion in 1973 dollars. To estimate the cost per flight in today’s dollars, we’ll follow these steps:

    1.    Adjust the total cost for inflation:
    •    The cumulative inflation rate from 1973 to 2024 is approximately 5.8 times. This means that $1 in 1973 is worth about $5.80 in 2024 dollars.

Total cost in 2024 dollars = $25.4 billion x 5.8 = $147.32 billion

    2.    Calculate the cost per flight:
    •    There were 17 Apollo missions, including the uncrewed and crewed missions.

Cost per flight = $147.32 billion/17 = $8.67 billion per flight

Summary:

The Apollo program cost approximately $147.32 billion in today’s dollars, which breaks down to about $8.67 billion per flight on average.

 And we already know Apollo was not sustainable.

In contrast, ~$100 million for expendable SuperHeavy/Starship at 200+ ton capability gets single launch missions to the Moon at costs nearly two orders of magnitude cheaper than Apollo or Artemis. This is in the same range of what NASA spends for just flights to the ISS.

For Mars, NASA once presented a plan to the George Bush, the senior, administration for a Mars program for a total cost of $500 billion. This was promptly rejected by the administration. These large cost estimates led Robert Zubrin to propose in the early 90’s his Mars Direct approach, where propellant for the return flight would be generated at Mars.

This would require only 2 launches of Saturn V class launchers at 100+ ton capability. With the development of the Starship at 100+ ton ability reusable, Zubrin proposed using it in his Mars Direct 2.0 proposal. He contrasted this from the SpaceX approach of using multiple refuelings here:

Mars Direct 2.0 - Dr. Robert Zubrin - IAC 2019.
https://www.youtube.com/watch?v=z5k7-Y4nZlQ

Zubrin notes by just using a small 3rd stage/lander you would need no refueling flights.

But you have to wait until the time the Starship becomes reliable for reusable manned flights.
 In contrast the expendable version with its higher payable capability can launch now and needs only a single launch, not two.

Demo flights to either the Moon or Mars can literally launch within a month on IFT-5 if stripped of its reusability systems to get the 200+ ton payload capability.

  Bob Clark

Edited August 11 by Exoscientist

[RCgothic]

I still don't understand why anyone would just want a repeat of Apollo. It'd land twice and get cancelled. The way EUS is going it might not even manage that.

The goal is permanently inhabited lunar bases and crewed beyond earth-moon explorations. Tanker flights get us that. With that within our grasp I don't care at all about pathetically undersized single stick missions.

[AckSed]

I do get it, really I do. It's exciting to know that they have a booster that makes Saturn V look underpowered. Hell, when IFT-3 took off I told my housemate it could be a disposable heavy-lift booster right now. However, I don't think you should conflate "could do it" with "should do it" or "will do it". Take into account merely human will.

I feel reasonably confident that now they have IFT-4 and a rather melty second-stage re-entry under their belt, SpaceX will continue to develop Starship as a reusable second stage, despite the multi-faceted and extensive technical challenge. Because unlike their start when they developed reusability for the Falcon 9, SpaceX is making money, and both Musk and Shotwell believe in the Mars mission, however foolish you might think it is. I'd venture a large amount of the senior engineers believe in the Mars mission too, or at least the prospect of designing a fully-reusable second stage.

[tater]

1 hour ago, RCgothic said:

I still don't understand why anyone would just want a repeat of Apollo. It'd land twice and get cancelled. The way EUS is going it might not even manage that.

The goal is permanently inhabited lunar bases and crewed beyond earth-moon explorations. Tanker flights get us that. With that within our grasp I don't care at all about pathetically undersized single stick missions.

This. Wanting Apollo 2 at all is insipid. Do something new/useful, or don't bother. The only reason the first landing with 2 crew should even exist is to test equipment for real missions. Testing equipment that merely lands a couple people, or even 4 is similarly uninteresting.

Assuming NG flies in September (big if), the notion of a program based on a system that is headed towards costing 6-7 BILLION per launch is nothing short of insanity. By the end of the year we'll have 2 cost effective medium lift vehicles (F9 and Vulcan), 2 cost effective heavy lift vehicles (FH and NG), and one super heavy lift vehicle (SS/SH)—assuming it is ever used with all or part expended. Then we have the one heavy that's too expensive to be useful (SLS Block 1), and future super heavy that's also grossly too expensive to be useful (SLS Block 1B).

Nothing will ever make SLS cost effective, the sooner it's obviated, the better.

[darthgently]

1 hour ago, AckSed said:

I do get it, really I do. It's exciting to know that they have a booster that makes Saturn V look underpowered. Hell, when IFT-3 took off I told my housemate it could be a disposable heavy-lift booster right now. However, I don't think you should conflate "could do it" with "should do it" or "will do it". Take into account merely human will.

I feel reasonably confident that now they have IFT-4 and a rather melty second-stage re-entry under their belt, SpaceX will continue to develop Starship as a reusable second stage, despite the multi-faceted and extensive technical challenge. Because unlike their start when they developed reusability for the Falcon 9, SpaceX is making money, and both Musk and Shotwell believe in the Mars mission, however foolish you might think it is. I'd venture a large amount of the senior engineers believe in the Mars mission too, or at least the prospect of designing a fully-reusable second stage.

Agreed.  I'm not even convinced Musk is all in on Mars as a solid goal.  His point is broader and deeper. 

He's made this broader point many times in many conversations and interviews and it always rings quite sincere and consistent.  He simply feels very strongly that humanity, to be happy, perhaps to survive at all, needs a challenge that requires a bigger vision and venturing into the unknown. 

I would put good odds on him simply seeing the Mars thing as something people can imagine and the problems solved pushing towards it will bear positive fruit not just technologically, but psychologically and sociologically.  He didn't have to twist my arm; I've always thought that humans without a frontier quickly become nihilistic, small-minded, and mean.

Apollo has already been done, we need to turn it up a notch

https://youtube.com/shorts/bHBAG71uij8?si=NKQF309P6Q7LW-3P

Edited August 12 by darthgently

[tater]

Meanwhile, a new F9 stage 2 is in space, booster landed.

 

It's tedious to have to edit x to twitter to get them to embed... wonder if the forum software ever catches up?

[RCgothic]

5 hours ago, tater said:

This. Wanting Apollo 2 at all is insipid. Do something new/useful, or don't bother. The only reason the first landing with 2 crew should even exist is to test equipment for real missions. Testing equipment that merely lands a couple people, or even 4 is similarly uninteresting.

Nothing will ever make SLS cost effective, the sooner it's obviated, the better.

Three times the expendable payload of Saturn V certainly makes an impressive benchmark, but it doesn't make for an impressive moon mission.

Replacing SLS with Superheavy fixes a cost issue at least, but it doesn't advance long-term goals. 

The only use cases I'd find interesting for a single-stick expendable launch are truly enormous monolithic payloads to LEO. But even space stations and telescopes don't need that, just send them up in segments.

Currently the only thing I can think of might be a very large nuclear powered tug where the reactor can't be subdivided.

[darthgently]

3 hours ago, RCgothic said:

Three times the expendable payload of Saturn V certainly makes an impressive benchmark, but it doesn't make for an impressive moon mission.

Replacing SLS with Superheavy fixes a cost issue at least, but it doesn't advance long-term goals. 

The only use cases I'd find interesting for a single-stick expendable launch are truly enormous monolithic payloads to LEO. But even space stations and telescopes don't need that, just send them up in segments.

Currently the only thing I can think of might be a very large nuclear powered tug where the reactor can't be subdivided.

What about a scaled up, but still folded, JWST?  That would be a huge telescope.  

[mikegarrison]

On 8/10/2024 at 4:08 PM, darthgently said:

I do recall a 100 passenger number way back in the before times when Starship was just artistic renderings, the design was very fuzzy and whimsical, and the context, iirc, was one-way colonization transport after many prior missions had established infrastructure.

It was always ridiculous, and many people (in this forum and elsewhere) pushed back on it immediately.

11 hours ago, RCgothic said:

The goal is permanently inhabited lunar bases and ....

Why? What's on the moon other than a lot of radiation and no air?

[tater]

3 hours ago, mikegarrison said:

Why? What's on the moon other than a lot of radiation and no air?

It's the most interesting place we can go that is close, and allows testing our abilities in that area to push some TRLs I guess. Most hab concepts for extended lunar stays have similar constraints to the same sort of facility on Mars—as you say, the radiation environment is harsh—but the same solutions for the Moon do apply to Mars (covering habs with regolith). Better to test solutions 3 days from home than over a year from home.

The nominal point of Artemis is of course a "sustainable' lunar presence, and the hope is for work on ISRU using lunar water ice making the facility a propellant source.

[darthgently]

1 hour ago, tater said:

It's the most interesting place we can go that is close, and allows testing our abilities in that area to push some TRLs I guess. Most hab concepts for extended lunar stays have similar constraints to the same sort of facility on Mars—as you say, the radiation environment is harsh—but the same solutions for the Moon do apply to Mars (covering habs with regolith). Better to test solutions 3 days from home than over a year from home.

The nominal point of Artemis is of course a "sustainable' lunar presence, and the hope is for work on ISRU using lunar water ice making the facility a propellant source.

Further, not any time soon, but at some point our knowledge of ecosystems, biology,  AI, etc. will allow us to create habitable environments full of life and they won't be limited to surface or subsurface bases.  Small steps matter as the progress is cumulative.  Geometrically and exponentially in many cases

[AckSed]

5 hours ago, mikegarrison said:

Why? What's on the moon other than a lot of radiation and no air?

In addition to the 'testbed for Mars' case, in terms of raw resources there's a lot of oxygen that can be baked out of the regolith, aluminium and titanium ore, magnesium and calcium too, and a much-reduced gravity well compared to Earth.

While the Sun is up on the Lunar day, you have heat and light to run as many solar panels as you want, and the materials to build as many as you want. Blue Origin's "Blue Alchemist" made a solar cell out of regolith simulant, so they're clearly thinking about this. The lower gravity may also make semiconductors easier to make.

Energetically, Earth-Luna L5 is right next door, something like 1.7km/s delta-V to reach Low Luna Orbit, then 0.7km/s to L4 or L5.

If one were serious about building a full-fledged artificial-gravity L5 space station that telepresencing workers could live on, building the solar panels, framework and shielding from Lunar materials would be much less painful than shipping it from Earth.

[zolotiyeruki]

5 hours ago, darthgently said:

What about a scaled up, but still folded, JWST?  That would be a huge telescope.  

I have to wonder how much attention NRO is paying.  The size of the optics you could put on a spy satellite that fits inside Starship must surely have some folks salivating.