Thread: SpaceX - On to Mars

Buildup of Starship continues ahead of Elons presentation scheduled for 2019/09/28.


Picture by Elon Musk in a tweet Droid Junkyard, Tatooine



Another tweet by Elon Area 51 of Area 51

Tension is rising ahead of the presentation which will be at 7:00PM US Central time on Sept. 28. Work is going on in 3 shifts to get Starship ready by then.




The 3 Raptor engines already installed, temporary install. Full engine set will be the 3 sea level Raptor you see on the photo, plus 3 vacuum Raptor, much bigger and more efficient in vacuum.

If anyone wants to watch the presentation live, here the link. If you click it there is a countdown clock.

They are working on it to the last minute. Over night they have added legs and right now they are adding the nose cap. Until now there was still a hole at the top.

I watched the presentation. It contained little that was new except an amazing animation how the rocket reenters using the aero surfaces. Completely new and different to things ever done before. Here a short version well worth watching instead of the full presentation.




The ship as shown may do only one flight before it is retired. It is too heavy at 200t, just a first prototype. They will begin building a second prototype which will be much lighter at 120t and can be used for orbital flight. The plan had been to build the first stage next, the SuperHeavy booster but that was changed. They need the next lighter version of Starship and also the booster needs a lot of engines, up to 37 and the production rate is not yet up to produce that number quickly.

The estimate for developing Starship had been $2-10 billion. He now narrowed it down to $2-3 billion. First orbital flight in about 6 months.

If everything goes very well, they may do the first manned flight late next year. Of course everything going well never happens. Not with SpaceX and certainly not with any other rocket company.

He also emphasized that getting humanity off Earth is quite urgent. Earth may be habitable only a few hundred million years before the sun becomes too hot. The time to move is now.

He also said, keeping Earth habitable now should receive 99% of available resources. But 1% should be spent off planet.

The bottom section of Starship was tested yesterday under pressure and failed. The top bulkhead blew off and according to estimats flew over 100m high before coming down to Earth. A good video of the event from Scott Manley. Worth to watch in total but you can see what can be seen in the first minute of it.



The tank was filled with liquid nitrogen. Pressure tests are done with liquids. If a pressure vessel fails the result is much more catastrophic when pressurized with gas. The liquid nitrogen shockfroze everything close to the tanks.

This part, the Mk1 is beyond repair. They will move on to Mk3 instead of replacing it. They still have the Mk2 in Florida which is quite close to the same level of completion. They could continue testing with that. However the rumor mill has it that they had already decided in the days ahead of this pressure test that Mk1 and 2 won't fly as previously intended. Only the orbital capable Mk3 at Boca Chica Texas and Mk4 in Florida will fly.

Edit: BTW that cherry picker was not manned. It only held a camera. The area was closed and evacuated for this test. Nobody was injured.

^ I'm sorry, but when I look at that structure I can't help thinking Wallace & Gromit....

...as for the landing on return, KISS or expect failures...

Originally Posted by Troy

^ I'm sorry, but when I look at that structure I can't help thinking Wallace & Gromit....

...as for the landing on return, KISS or expect failures...

Never mind. Few people will believe this works, fewer it works as fast as SpaceX intends, until they fly it to orbit and return it.

They are hiring. Building a much more advanced replacement won't take half a year.

The plan is to be able to fly it several times a day and fly it a few thousand times. Airline like operations. They admit that there is a chance they may fail.

So, what % of normal operating pressure was it tested at? The commentator suggests 3 to 5 x atmospheric.

Originally Posted by OhOh

So, what % of normal operating pressure was it tested at? The commentator suggests 3 to 5 x atmospheric.

Normal flight pressure would be in the range of 3 atm. We don't have specific numbers for Starship but it won't be more than that. 5 would be quite high even for tests. Unlike tanks on Earth they don't have margins for more than twice operational pressure.

Some info on tank pressurization. It has a dual purpose and is absolutely needed for flight.

One purpose is to let the engine turbopumps operate. They need the head pressure to take in the propellant. I don't know exact numbers but the engines of a large rocket like Saturn V or the Starship booster need a lot of power to transport the propellant to the combustion chamber. A lot more power than all electric power plants of California combined produce, just to give you a rough idea.

The second purpose is stability of the rocket in flight. Most rockets are built so they can stand up to the weight of the payload and the propellant while on the ground. But when the rocket lifts off and accelerates the weight increases and the pressure keeps them stable in the additional load. For comparison an empty soda can is fragile, closed and under internal pressure they become very sturdy.

transporting the propelant to the combustin chamber, wouldn't gravity do that naturally? maybe a naive question

I am not sure I got your reference of the turbo pumps taking the whole electricity power of CA to function, that seems a bit OTT and not realist, that's a lot of MegaWatts

Is the SpaceX resistant to insects?

Scientist believes he has spotted insects on Mars
An emeritus entomologist from the US causes a stir, though not for approval
20. November 2019, 14:11


A 50 centimeter long Mars insect ... or maybe just a normal stone?
Foto: Dr. William Romoser

If he were still in the middle of an academic business, he would probably have done no favor with this performance. But William Romoser of Ohio University retires after a 45-year career as an entomologist, that is, entomologist, and does not have to worry much about careers.


And so, at the recent Entomological Society of America meeting in St. Louis, he presented a theme that stood out from the spectrum of lectures held elsewhere and is now making headlines and raised eyebrows around the world: Romoser is sure to find images of Mars Having discovered insects of considerable size.

The alleged find

Romoser claims to have studied freely accessible photos of various Mars missions on the Internet - especially the Rover Curiosity - and thereby encountered numerous insect-like life forms. Segmented bodies, legs and antennae are typical of arthropods, and a six-leg number would require earthy terms to speak of an insect.

And he goes even further: The Rover photos would not only show fossilized exoskeletons of Mars insects, on some images you can even see live specimens: a kind of hive as well as washed-out impressions of an animal that is currently in a dive and then pulling up again just before serving. Even a kind of snake is to be seen on one of the pictures. For Romoser, there are all signs of a species-rich Martian fauna: "There was and still is life on Mars."

Optical illusion

The first reactions to Romoser's lecture, which Ohio University had ennobled, after all, with an official broadcast, were as much to be expected as unanimously rejecting. And the interpretations also all go in the same direction: Romoser was absorbed in the pareidolia, a perceptual phenomenon that allows us to "recognize" familiar patterns even where they do not exist. The supposed insects are nothing but rocks.

Read more (in deutsch):
https://www.derstandard.at/story/200...chtet-zu-haben

Originally Posted by Troy

I'm sorry, but when I look at that structure I can't help thinking Wallace & Gromit....

that cartoon rocket looks more solid and reliable than the Space X prototype,

Originally Posted by Dragonfly

that's a lot of MegaWatts

It really is. It takes that much power. Several MW for each of up to 36 or 37 engines.

Originally Posted by OhOh

Am I right in assuming the turbo pumps spin unpowered initially and allow enough oxygen and fuel into the engines to start the rocket engines, because the oxygen and fuel tanks are sufficiently pre-pressurised?

They use a reservoir of high pressure gas to spin up the turbopumps. That gas also precools the turbopumps so they don't get damaged by cold shock when the super cold liquid oxygen and liquid methane comes to the intake.

For pressurizing the tank on their Falcon rockets they use helium. Elon Musk once stated the helium costs more than the kerosene and LOX propellant. For Starship they use a different method. They boil some of the LOX for the LOX tank and some methane for the methane tank. In flight that hot gas comes from the engines. Two reasons for that. Using helium may double their launch cost, if they get their cost as low as they intend. Second they want to produce the fuel on Mars. They won't have helium there.

Thanks.

BTW using the term propellant is something I do. Most people say just fuel, which is not quite correct.

There is the fuel, usually RP1 (rocket grade kerosene), or liquid hydrogen or with some older simpler designs hypergolic fuels. Then there is the oxidizer, usually liquid oxygen or dinitrogentetroxide for hypergolic fuels. Dinitrogentetroxide is what makes the red cloud when another chinese first stage falls down on some village like again last night. Hypergols are cancerogen. Fortunately they don't linger in the environment. They turn into nitrogen fertilizer when in contact with humidity.

Both fuel and oxidizer combined are the propellant but that term is rarely used except by me nitpicking.

Not to forget the new generation rockets, Starship of SpaceX with the Raptor engine. ULAs new Vulcan rocket and Blue Origins New Glenn using the BO BE-4 engine use methane as fuel with LOX as oxidizer. The russians had experimental methane engines very early but never developed them to operational state and never used them on rockets.

Originally Posted by Dragonfly

that cartoon rocket looks more solid and reliable than the Space X prototype,

That's because it is.

This was just another failed diversion from his failing car company. The guy is the biggest fraud of our age.

Originally Posted by Backspin

This was just another failed diversion from his failing car company. The guy is the biggest fraud of our age.

This comment looks like Nam Prick Tootie's avatar. Straight out of your ass...