totm nov 2023 SpaceX Discussion Thread

[tater]

As for docking 2 CCVs together, I'll admit I'm confused  by the NASA Docking System. I'd have thought the point of androgynous ports was exactly to allow either side to be active. Apparently there is a permanently passive variant as well...

The point would be maybe contingency operations. If there was a free-flier Dragon, and another vehicle existed that could be sent to rescue (unlikely, but assume it's a thing), then you could do that.

You'd think in future this would be desirable for all spacecraft to be able to transfer crew. Dragon to Starliner, Starliner to Starship or Orion, any to a future lander, etc.

[SpaceFace545]

1 hour ago, Spaceman.Spiff said:

No way, not enough room for supplies. and it's still barely enough for one person, not to mention power requirements, bathroom requirements, and other important functions. Dragon is not going outside of LEO without massive changes.

Yeah, a deep space dragon would generally just have to get bigger and would  probably end up as a curvier Orion. But Orion on deep space missions would dock with a much larger transfer ship with living accommodations and without an equivalent a deep space dragon would be useless.

[SpaceFace545]

25 minutes ago, tater said:

You'd think in future this would be desirable for all spacecraft to be able to transfer crew. Dragon to Starliner, Starliner to Starship or Orion, any to a future lander, etc.

I agree, I think with an evolving space economy truly androgynous ports and a universal system will be necessary to allow cooperation. 

1 hour ago, Spaceman.Spiff said:

That proposal was.... interesting. It included dragon propulsive  landing and being used as habitats.
I think its goals are now focused on LEO and maybe lunar space. 

I don’t really know if it was a dream or I saw something but I remember seeing a crew dragon turned into low gravity lander on somewhere like Deimos or a low gravity object.

[tater]

11 minutes ago, SpaceFace545 said:

Yeah, a deep space dragon would generally just have to get bigger and would  probably end up as a curvier Orion. But Orion on deep space missions would dock with a much larger transfer ship with living accommodations and without an equivalent a deep space dragon would be useless.

Crew Dragon has ~1/2 the volume of Orion—but the quoted Orion figure is I think the total pressure vessel, not the usable volume (and I have no idea if the Dragon vol quoted is total or usable, either, who knows, lol).

In general, neither is meant for long term missions (or Starliner for that matter). Orion was supposed to haul people to ISS in its first incarnation after all, and any lunar mission it was to be docked to Altair in LEO, substantially increasing crew volume. For Mars DRAs, Orion delivers crew to a huge vehicle, then then next time they enter Orion it's for EDL to home.

Using any as a taxi seems reasonable, but not ideal for long trips.

1 minute ago, SpaceFace545 said:

I agree, I think with an evolving space economy truly androgynous ports and a universal system will be necessary to allow cooperation. 

Yeah, all nations, too.

Part of the problem is the pressure suits used on launch and EDL are not EVA suits, so emergency crew transfers are just not a thing unless they can dock. Some work along those lines might also be useful. The beauty of those skin tight suits MIT has worked on is that they could possibly be worn on launch and landing, and they might stuff into a small space—and they have to have helmets anyway.

[tater]

7 minutes ago, SpaceFace545 said:

I don’t really know if it was a dream or I saw something but I remember seeing a crew dragon turned into low gravity lander on somewhere like Deimos or a low gravity object.

SpaceX threw out Red Dragon as an idea (which as far as I ever saw was just throwing a Dragon to Mars, and having it land proplsively as a test). The Dragon with people around the Moon was the original #dearmoon concept. I read people talking about "gray Dragon," but that honestly might have been people noodling around with concepts on NSF or here.

Mars in that sense is actually easier, since Dragon is already designed to shed almost all its velocity via the atmosphere, so the Super Dracos just kill whatever terminal velocity is on Mars for Dragon.

(I'm completely discounting the Mars One goons, because they deserve to be discounted—though I might actually enjoy watching a Mars "Donner Party" reality show)

 

[Spaceman.Spiff]

8 minutes ago, tater said:

I'm completely discounting the Mars One goons, because they deserve to be discounted—though I might actually enjoy watching a Mars "Donner Party" reality show)

I am...... intrigued?

was cannibalism involved I’m very confused?

[Flying dutchman]

Has Starship done a static fire yet?

 

Edit: yes

Edited April 27, 2021 by Flying dutchman

[SpaceFace545]

22 minutes ago, Spaceman.Spiff said:

I am...... intrigued?

was cannibalism involved I’m very confused?

I would love to watch the first Mars settlements go full Jamestown as the colonists turn their society into a canabilistic autocracy like the pilgrims. All while sipping some nice whisky (really anything would be nice, those fools on Mars only would have water to drink) that those silly colonizers couldn’t bring to save on weight.

[sevenperforce]

3 hours ago, SpaceFace545 said:

I also could care less about who that gwynne lady is, just another musk fanboy who climbed the ranks to spew more technobabble. 

Well that's not sexist at all

53 minutes ago, tater said:

SpaceX threw out Red Dragon as an idea (which as far as I ever saw was just throwing a Dragon to Mars, and having it land proplsively as a test). The Dragon with people around the Moon was the original #dearmoon concept. I read people talking about "gray Dragon," but that honestly might have been people noodling around with concepts on NSF or here.

Yeah that was me.

[tater]

43 minutes ago, Spaceman.Spiff said:

was cannibalism involved I’m very confused?

Yes. The Mars One loons had a sort of crowd-sourced idea that they would buy SpaceX flights to Mars (in crew Dragon) and go one-way to Mars. As if people could live in Dragon in deep space for months—then on Mars... forever.

2 minutes ago, sevenperforce said:

Yeah that was me.

LOL, loads of posts over the years, hard to remember exactly.

 

[kerbiloid]

 

3 hours ago, Spaceman.Spiff said:

3 hours ago, SpaceFace545 said:

I guess it would be sorta cool to send up a cargo dragon and dock a crew dragon to that to make some type of mini space station.

Maybe for a rescue? But I guess its still possible, there would just need to be a special "Rescue Dragon" with a passive port.

No, it's not possible.

Cargo Dragon doesn't have a docking port at all, only the passive berthing mechanism.

The passive IDSS port also can not be used for docking, it's not just "plug and outlet".
It can't extend.  So, can't adjust.

Also the Crew Dragon has no room for the peripheral docking targets at all (1 PDT and 3 PRT), and unlikely has room in the tunnel to put CDT and something to attach it to.

  

3 hours ago, tater said:

A questionable company with 2 crew vehicles attached to ISS as we speak.

With contracts from NASA and Pentagon had gotten before they built the rocket?
What if this money was given to Bezos instead?

It looks like somenody in NASA has on hold at the pawnshop his wife, his kids, and both kidneys, to lobby SpaceX, and has no way back.

  

2 hours ago, Spaceman.Spiff said:

That proposal was.... interesting. It included dragon propulsive  landing and being used as habitats.

The proposal was a cheap hype with nothing rational behind it.

2 hours ago, tater said:

If there was a free-flier Dragon, and another vehicle existed that could be sent to rescue (unlikely, but assume it's a thing), then you could do that.

If modify the CrewDragon port by adding the passive hooks, and anyway by docking without targets, just intuitively.
Would not work.

They just treat the rescue flight possibility as impossible.

1 hour ago, SpaceFace545 said:

Yeah, a deep space dragon would generally just have to get bigger and would  probably end up as a curvier Orion.

It would end up before getting something, because of the engines and fuel tanks in the capsule. A rather strange technical decision.

Deep space Dragon sounds nice, but what is it's L/D. It looks closer to Soyuz than to Apollo, and has heavy tanks and engines aside.
Can it even survive 11 km/s re-entry?

 

Edited April 27, 2021 by kerbiloid

[Flying dutchman]

...

I don't like what this thread has become.

Edited April 27, 2021 by Flying dutchman

[tater]

22 minutes ago, kerbiloid said:

If modify the CrewDragon port by adding the passive hooks, and anyway by docking without targets, just intuitively.

I'm honestly not sure how Dragon docks itself to ISS. Is it visualizing the targets markers, or is it using known positions fed by telemetry, or simply visualizing the docking port? It's objectively far easier than self-driving a car I think (no little kid will run in front chasing a ball).

Presumably a target could be added to the folded nose cone?

 

Meanwhile at Boca Chica, SN16's nose cone is now stacked, with fins.

[kerbiloid]

1 minute ago, tater said:

I'm honestly not sure how Dragon docks itself to ISS.

IDA/PMA is equipped with full set of docking targets.
Dragon is equipped with TriDAR.

[tater]

26 minutes ago, kerbiloid said:

With contracts from NASA and Pentagon had gotten before they built the rocket?

NASA invested chump change in F9/Dragon.

They spent a little over $2B on Crew Dragon/Cargo Dragon, including the first few launches. A reasonable deal, and still not a lot of money in the grand scheme (my small city's public school system has a larger annual budget than Crew Dragon cost NASA).

1 minute ago, kerbiloid said:

IDA/PMA is equipped with full set of docking targets.
Dragon is equipped with TriDAR.

So inertial navigation gets it in the vicinity, pointing at ISS, then it uses that. Gotcha.

[kerbiloid]

14 minutes ago, tater said:

Presumably a target could be added to the folded nose cone?

It's too narrow. They should be around the docking port, inside a diameter ~13:9 larger than the hard-capture ring, and the spherical target has to see 45° backwards..

Orion and CST-100 also have that diameter covered by the chute box.

No ship-ship in foreseeable future (of course, if not Starships)

Edited April 27, 2021 by kerbiloid

[RCgothic]

4 hours ago, SpaceFace545 said:

I full heartedly believe that all 2.9 billion of those dollars will go to the further development of elon's mars express instead of the proposed lander.

It's a fixed price contact and they get paid on milestones. Don't deliver? Don't get paid.

[mikegarrison]

5 hours ago, tater said:

Undercutting on price is another matter, and perfectly legitimate

This is not always true.

First of all, certain types of undercutting pricing are fraud. For instance, if you learn through non-public sources what your competitors are bidding and use that information to adjust your own bid, that's illegal. Many companies have been caught doing that over the years, and the penalties for it are pretty draconian.

For example, McDonnell Douglas managed to acquire a large number of confidential documents (a whole roomful, if I recall correctly) from Lockheed Martin. This was before they merged with Boeing, but it was discovered after the merge. A bunch of contracts were shifted from Boeing to Lockheed Martin. There were also penalties paid. And stuff like this can result in people going to prison, too.

Another kind of undercutting is deliberately low-balling cost estimates. Sometimes this happens accidentally, but sometimes it is intentional. Once the contract is awarded and now the entire program is dependent on this single source, suddenly things get more expensive. Change orders happen, and the price goes up. It becomes a game of brinksmanship with the program being held hostage. It's hard to prove when this is deliberate or just caused by overconfidence, unless there is a convenient trail of documents that prove some kind of bad intent.

[KSK]

2 hours ago, kerbiloid said:

The proposal was a cheap hype with nothing rational behind it.

I don't think that's entirely fair.  It was a bit of a stunt but a stunt with the serious purpose of testing supersonic retropropulsion at Mars.  I think I remember reading that SpaceX would have shared that data with NASA who were understandably interested in studying it for their own Mars missions.

6 hours ago, SpaceFace545 said:

I full heartedly believe that all 2.9 billion of those dollars will go to the further development of elon's mars express instead of the proposed lander. *snip*.  But all in all NASA got conned.

I certainly hope so. If SpaceX can't learn some valuable lessons from building a Moon lander and use them to help develop a crewed Starship for eventual flights to Mars, I'll be very disappointed.  And, for what it's worth, NASA don't seem to think they got conned. Quoting directly from NASA's Source Selection Statement for the Artemis human lander system:

"Within Management Area of Focus 4, Commercial Approach, I found SpaceX’s significant strength for its comprehensive plan to leverage its HLS contract performance to advance a multi-faceted approach to commercializing its underlying Starship capability to be a highlight of its management proposal. SpaceX’s plans to self-fund and assume financial risk for over half of the development and test activities as an investment in its architecture, which it plans to utilize for numerous commercial applications, presents outstanding benefits to NASA."

Emphasis added. 

[kerbiloid]

20 minutes ago, KSK said:

I don't think that's entirely fair.  It was a bit of a stunt but a stunt with the serious purpose of testing supersonic retropropulsion at Mars.

Dragon engines can produce 6 g acceleration.
The Martian gravity is 0.4 g,
So, they are 15 times overpowered for a Martian landing, they should be landing at 6% of thrust.

So, it was another Tesla car in space.

Upd,
Btw. If deliver Tesla to Mars, can it have a ride there? It doesn't need air. so what if.

Edited April 27, 2021 by kerbiloid

[Philae_Rosetta2021]

Is it just me, but the Moonship doesn't seem all that stable to land on the Moon. It just seems a bit, well, tall.

I understand why, but I would like to know what stops it from falling over if it doesn't land just right so.

[KSK]

23 minutes ago, kerbiloid said:

Dragon engines can produce 6 g acceleration.
The Martian gravity is 0.4 g,
So, they are 15 times overpowered for a Martian landing, they should be landing at 6% of thrust.

So, it was another Tesla car in space.

Upd,
Btw. If deliver Tesla to Mars, can it have a ride there? It doesn't need air. so what if.

Oh for sure Dragon’s engines had more than enough thrust to land on Mars - assuming that they could light in time.

Relighting the Merlin engines for propulsive landing on Earth obviously isn’t a problem now but lighting a different engine in a thinner atmosphere but (probably) at much higher speeds is a whole other question.

And of course, doing the same with Raptor is yet another question which I’m guessing is why the Red  Dragon concept has been ditched - any data that SpaceX could get from it won’t be relevant to Starship.

Edited April 27, 2021 by KSK

[Hannu2]

18 minutes ago, kerbiloid said:

Btw. If deliver Tesla to Mars, can it have a ride there? It doesn't need air. so what if.

Probably you could get very short drive immediately after you turn electronics on. But practically all electronics on Earth is very dependent of air cooling. Power electronics of the car would overheat very soon in Martian conditions. No only large FETs which control main current for motor but also processor boards before you begin to actually drive. Those tiny components need also air to absorb heat.

[mikegarrison]

30 minutes ago, Philae_Rosetta2021 said:

Is it just me, but the Moonship doesn't seem all that stable to land on the Moon. It just seems a bit, well, tall.

I understand why, but I would like to know what stops it from falling over if it doesn't land just right so.

It's all a matter of cg location.

Unfortunately, for dynamic stability you want the cg to be toward the nose, while for stability standing on the surface you want the cg to be toward the tail.

At least on the Moon there are no wind loads.

[kerbiloid]

Landing on Gilly makes it bouncing at greater amplitude than on Mun.

P.S.
A landed Martian Tesla could make a circle around the landing, accelerate, and jump from a cliff.

With a pair of boring flamethrowers from back and an oxygen balloon to let them fire.

A manequin in SpaceX suit could eject and chute in flight.

Edited April 27, 2021 by kerbiloid