Space and Science BS Thread

Didn’t think HLS Starship would have to be in a NRHO but if it’s docking with Gateway for crew transfer..

 

Good stuff for the non initiated - free:
https://solarsystem.nasa.gov/basics/

 

That's literally the plan.

Again, that's the plan. Since the HLS solicitation is for gateway <> lunar surface <> gateway transportation.

Yes, it's going to take a lot of launches. Good thing there's a reusable second stage involved in the 'fueling up' vehicle so you're just paying the cost of fuel, huh?

The tanker topping off HLS at Gateway isn't on a free return trajectory. It's going to Gateway. It's then going to make a burn to get back to terra firma - at which point it can use the atmosphere to slow down.

I guess it can always do an elliptical orbit that goes from NHRO to LEO but that opens up only limited windows for fueling and it'll still need to burn to rendezvous with gateway once it's topped off, and that relies a lot more on waiting for transfer windows and the like.

 

HLS is in NRHO and needs to be refueled. So Spacex launches tanker 1 into LEO with 100 Tons of propellent for HLS. Then it launches tanker 2 into LEO docks with tanker 1, refuels tanker 1's drive tanks with 100 Tons, and then tanker 2 lands back on earth. They refill tanker 2, relaunch, redock with tanker 1, add 100 tons more propellent, and returns to earth. Rinse and repeat 6 times to get tanker 1's drive tanks to 50% capacity, 12 times for 100% capacity. Tanker 1 now has enough fuel to deliver 100 tons of fuel to HLS. Tanker 1 can then return to earth or earth orbit to start the whole process again because it has to return to NRHO another 5-11 times. I'm not saying that NASA isn't crazy enough to do that, but I just don't see it making sense logistically. I think the HLS can burn off that dv for far less fuel and far less wear and tear on tanker 2's TPS. It's just far more likely that they will do a combination of some eccentric elliptical orbit, boost back burns, and waiting for windows so that they can fill up HLS with 6-12 rockets as opposed to 72-156 rockets.

Then again there is always the possibility that they won't refuel them beyond the first time in LEO. They could send it to the moon, land it, launch it, and then leave it in orbit docked to the gateway as additional room. Considering it's pretty much as large as gateway, they could quickly gain some orbiting real estate. Or Elon could create some kind of docking hub and create the first private space station.

 

The leaving it and launching a new one actually makes a bit of sense now that I think about it. To get a fuel production facility and a permanent base on the moon is going to require dozens of moon rockets, many with large pieces of equipment that won't be easy to move, even weightless in space, let alone between rockets. My money is now on them not refueling them at all once they're to the moon. Once they prove they can land and launch one from the surface they will likely start landing dozens filled with equipment and supplies.

 

Will SpaceX test a landing on the moon or will they just do it manned? WOuld be expensive i would think for a test landing.

 

Starship is super cheap comparatively. They will likely do several test landings before a manned landing. Their plan for mars was/is to send 6+ ships to land before manned landings. Probably going to follow the same plan for the moon.

 

The 2.98 B includes one demonstration landing and one crewed landing.

It’s gonna be a trip.
Will they use the same Starship? Time’ll tell.

Edit: $5 it’ll be the same Starship...

 

One demonstration and one crewed.

 

https://www.nasa.gov/sites/default/files/atoms/files/option-a-source-selection-statement-final.pdf

https://www.nasa.gov/nextstep/humanlander2

 

Tanker 1 isn't going to return to earth orbit, it'll return to earth aerobraking in the process, as circularization burns takes fuel.

Also, remember highly elliptical orbits will take it multiple passes through the radiation belts - generally a not-so-awesome idea. In addition - going from a halo orbit to eccentric earth orbit and back to a halo orbit also takes fuel - fuel you're gonna want to use on the moon landing sequences.

Unmanned ones can be left - though the first run will be a demo mission to NASA to show how it's going to be an adequate taxi from gateway <> moon <> gateway, so it's not going to be left. Nor will any crewed ones (for obvious reasons).

As part of the HLS contract, they are to do one uncrewed landing/return and one crewed landing/return to Orion.

...

Being SpaceX tends to have an iterative development process - HLS funding gives them a bit more flexibility.

They don't need to have functioning EDL to send up HLS. It's never coming home. That means that if SuperHeavy is working (and not even necessarily landing, though that of course would be nice), they can send it up. They also now have a 'paying customer' to send up tankers - which double as EDL test vehicles, to test their TPS scheme and make sure EDL is survivable for starship. Once there they can work on their stern-to-stern refuelling. That's a necessary step and needs to be demonstrated. Finally, tankers coming back from gateway/NRHO can be tests of mars-velocity EDL (it's closer to that velocity)

 

https://www.space.com/spacex-crew-2-astronaut-launch-final-review

 

4/22 GO GO GO

 

Burning fuel isn't a problem if they have it to burn. If when filled they have enough to go from LEO to NRHO to the surface of the moon, launch from the moon, and back to LEO, then that's what they will do as it is the most efficient. The alternative is literally 100's of 1000's of tons of fuel.

 

How many hours are 30,000 seconds?

https://www.spacex.com/updates/starship-moon-announcement/index.html


Seems like a deer-in-headlights kinda announcement...just MHO

 

Earth to LEO - 9.4 km/s
LEO to gateway is 5.2km/s of dV.
gateway to LEO - also 5.2km/s.
gateway to Earth Interface (aka, the atmosphere) .41 km/s
gateway to moon - 1.5km/s
moon to gateway - 1.5km/s

Yes, let's assume 100t of excess propellant per tanker. Let's say dry mass of a tanker is 100t, and the HLS is 200t. Prop capacity of both is 1000t. isp of rvac is 380.

According to my dV calculator, that means that a dry HLS has 6.6k of DV to spend, starting from LEO. Going to gateway is going to make it expend 5.2km/s of that, leaving 1.2. Gateway to moon is 1.5, so round trip is 3km/s.... Might need more prop/less mass assumptions. In any case, starting from LEO leaves you with barely any fuel left to do a mission. Maybe enough for one. Definitely not two.

Now, since it's only 3km/s per mission, you don't need to actually fill up HLS all the way.

According to the DV calc, a 100t tanker has 8.9km/s of dV available. As it only expends 5.6k of that to get to gateway and back, that leaves it with 2.3km/s of dV worth of propellant left over - and that since we're assuming takers weigh half of HLS, that's gonna be about 1km/s of prop.
Or 3 gateway bound tankers to get a mission going.

 

Lol easy maths. / 3600 .. round down to 3000 and 10h - fudge factor .. so 8 or so. (calc says 8.3)

 

Artemis III mission goals:
1) Install lunar optimized GSE;
2) Assemble in situ methane and oxygen manufacturing components;
3) Turn on methane and oxygen manufacturing components.

 

From the article:

20-foot, illuminated, stainless steel monument

The Adams’ will be so proud!!

https://www.mos.org/press/press-releases/Nimoy-Memorial-Sculpture-at-Museum-of-Science