Starship On-orbit refueling - Options and Discussion

[TrevorMonty]

While I like idea of LEO-Gateway-LEO shuttle, SS is not best vehicle for this when only transferring few tons. Most of tanker missions fuel is used to move SS dry mass back and fore. A small purpose built shuttle could do round trip using 150 fuel, lot less if hydrolox.

Question is then, which such purpose-built shuttle?  When will that be available?  And will it be significantly cheaper than a twice-refuelled Starship (even if I don't believe the $2M/launch figure Elon envisions will be reached within that timeframe)?

My understanding is that ACES is not currently being developed.  Will Blue Moon or some auxillary part of New Glenn be able to shuttle back and forth between LEO and lunar/cis-lunar?  Any other crafts in development?

Blue are working OTV which is what BE7 is for besides lander. My guess is lander and OTV will be similar.

[rakaydos]

Or just use several micro-sats, with charged tethers, to drain the belts, and stop having to worry about it...

There is the classic Tethers Unlimited paper showing they can drain the belts with 10 small sats with charged tethers in a few weeks or so. But, who pays for it, and why? Because everyone benefits from it whether they paid in or not, especially GEO birds that slowly spiral orbit up to GEO with electric thrusters (since they avoid roasting their solar panels). One of those tragedy of the commons moments, best fixed by a multinational Space Guard service charged with keeping the spacelanes clear (space junk included). Though I could easily see SpaceX doing just because it was incidental to their ops.

https://web.archive.org/web/20190213154045/http://www.tethers.com/papers/ES_Remediation_IEEE_Paper.pdf

For a fuel depot service though, maybe cheat with equatorial LEO as the baseline as that's the lowest exposure? Though that doesn't help for other orbits...

This particular TotC has a Gordian knot solution- One person does it for awhile, everyone gets used to benifiting, then the person announces they will stop doing it unless they receive donations to continue.

[dcengineering]

If all Starship was ever going to do was an LEO-GW-LEO shuttle, I'd agree with you.  But the shuttle is merely the first capability, and the easiest one to get certified.  After that, SpaceX can bite off Earth EDL, followed by lunar landing/ascent, and finally launch from Earth with crew.  The order of these is up for debate, but the shuttle to and from NRHO is by far the lowest-hanging fruit.

Might be a bit awkward when the "shuttle" has more living space than the Gateway does 

I think you hit the nail on the head with your previous post. After reading through the whole thread, it seems a lot of the issues stem from the complexities and risk associated with these maneuvers while a crew is on board, when the likelihood of NASA crew certifying Starship anytime soon is almost zero. D2 has been in development for 6 years now and is still not certified even though Falcon 9 is a relatively simple rocket if you ignore the whole landing part (which is immaterial to its crew rating anyways).

What sort of insane timeline are we even looking at to crew certify Starship? While I am somewhat confident SpaceX can beat NASA's 2024 Moon landing goal, it would be little more than a capabilities demonstration when crew aren't allowed on board during this timeframe anyways.

In the short to medium term, we should probably assume that manned operations involving SS is going to require F9/D2 to get astronauts back and forth from orbit. 

[xvel]

NASA can only certify for their missions, besides there is no such requirement as NASA certification for human flights

[Paul451]

NASA can only certify for their missions, besides there is no such requirement as NASA certification for human flights

FAA does.

Currently they are allowing suborbital (and presumably orbital) human rocket flight to classify vehicles as "experimental", passengers as "test crew", and exempt the operators from strict requirements of passenger aircraft. However, that's essentially a courtesy. It would take only a slightly more hostile Administration or a single anti-SpaceX senior senator to make the FAA adopt stricter airline-like rules.

[joek]

NASA can only certify for their missions, besides there is no such requirement as NASA certification for human flights

Of course there is.  That is what CCP "certification" is all about (of which there are reams of documents).  In any case, this has nothing to do with this thread; take it elsewhere.

[joek]

Currently they are allowing suborbital (and presumably orbital) human rocket flight to classify vehicles as "experimental", passengers as "test crew", and exempt the operators from strict requirements of passenger aircraft. However, that's essentially a courtesy. It would take only a slightly more hostile Administration or a single anti-SpaceX senior senator to make the FAA adopt stricter airline-like rules.

They are referred to as "participants" or "non-crew".  And yes, there have been pushes to institute FAA certification rules, which have been a work-in-progress for years, and resisted by the industry as a whole; SpaceX is not the only one with a stake in the game (and arguably less than some others).

[TheRadicalModerate]

NASA can only certify for their missions, besides there is no such requirement as NASA certification for human flights

I'm much more interested in how Starship fits into--and eventually supplants--the Artemis architecture.  For that to happen, there is absolutely a requirement that NASA crew-rate Starship.

Could SpaceX do an all-private lunar surface mission?  I suppose so.  But it's a massive risk for very little reward.  There's not enough money to be made doing it, and an accident is a huge setback.  I'm betting that they'll be very, very conservative with lunar surface missions, and do them only under the aegis of Artemis.

They can likely get wilder and crazier with CLPS, and I'd expect CLPS missions to prove out a lot of the tech that will be used for crewed landings later on.  But that just gives something to feed to NASA to get the crew certification ball rolling for landings.  It's a lot easier to get the LEO-NRHO-LEO stuff up and running sooner.

[QuantumG]

Could SpaceX do an all-private lunar surface mission?  I suppose so.  But it's a massive risk for very little reward.  There's not enough money to be made doing it, and an accident is a huge setback.  I'm betting that they'll be very, very conservative with lunar surface missions, and do them only under the aegis of Artemis.

I believe they're very interested in Artemis and I'd L O V E to see what they've submitted already.

I expect they'll do an automated lunar landing on their own dime.

Then I think they'll do a flight around the Moon with private astronauts (with an eccentric Japanese flight assignment officer!)

Around then NASA will look pretty silly if they don't put government astronauts on the next flight. NASA doesn't like to be put in these situations, so they've probably already secured a seat on the free-flyer.

[ThomasGadd]

While SpaceX is developing crewed Starship for NASA flights they can use Dragon as a transfer vehicle for non-NASA flights people could choose...

[TheRadicalModerate]

While SpaceX is developing crewed Starship for NASA flights they can use Dragon as a transfer vehicle for non-NASA flights people could choose...

Are you suggesting doing LEO to NRHO in a D2?  Not gonna happen; there's not enough delta-v and D2 only has consumables for 7 days.  But using an F9/D2 to get to LEO so that a crew can transfer to/from a Starship, which takes it to NRHO, is pretty easy, and the crew system for Starship isn't very challenging.

[GregTheGrumpy]

While SpaceX is developing crewed Starship for NASA flights they can use Dragon as a transfer vehicle for non-NASA flights people could choose...

NASA choosing to go this route **when** SpaceX has already sent and returned non-NASA individuals will be seen as churlish as the Russians seemed with DM-1 visited the ISS.  I just don't see that happening.

[docmordrid]

While SpaceX is developing crewed Starship for NASA flights they can use Dragon as a transfer vehicle for non-NASA flights people could choose...

Are you suggesting doing LEO to NRHO in a D2?  Not gonna happen; there's not enough delta-v and D2 only has consumables for 7 days.  But using an F9/D2 to get to LEO so that a crew can transfer to/from a Starship, which takes it to NRHO, is pretty easy, and the crew system for Starship isn't very challenging.

And a lot cheaper than doing it with Starliner or SLS/Orion.

[spacexfanatic]

Hi everyone, I did love the idea of Starship refueling another Starship but I was thinking about a simpler way to get extra fuel by mean of attaching external  tanks (cheap, disposable)  to  SS that will rendezvous somewhere ? think it simpler than later concept that still  has to be proven.

[SkyRate]

Hi everyone, I did love the idea of Starship refueling another Starship but I was thinking about a simpler way to get extra fuel by mean of attaching external  tanks (cheap, disposable)  to  SS that will rendezvous somewhere ? think it simpler than later concept that still  has to be proven.

Sure, the aft cargo pods could be made into tanks without hurting the ascent aerodynamics, but:

1. It's not that unproven. Progress tanker/cargo craft have auto-docked with Salyut-6, MIR and ISS 100+ times. Not to mention all the air-to-air refueling going on every day.

2. It's not that much simpler. Those tanks would each have to have connectors, valves, plumbing and sensors. The main tanks already have them (for being loaded via the SH). And if you transfer the tanks using a robotic arm, you have to add the weight and complexity of the arm. If not, it's a big, dangerous, time-consuming EVA job. "Best part is no part."

3. It's heavier. This is an upper stage. Every kg of structure is a kg less to orbit. Strap-on boosters are acceptable because they are dropped so early during the launch.

[spacexfanatic]

Hi everyone, I did love the idea of Starship refueling another Starship but I was thinking about a simpler way to get extra fuel by mean of attaching external  tanks (cheap, disposable)  to  SS that will rendezvous somewhere ? think it simpler than later concept that still  has to be proven.

Sure, the aft cargo pods could be made into tanks without hurting the ascent aerodynamics, but:

1. It's not that unproven. Progress tanker/cargo craft have auto-docked with Salyut-6, MIR and ISS 100+ times. Not to mention all the air-to-air refueling going on every day.

2. It's not that much simpler. Those tanks would each have to have connectors, valves, plumbing and sensors. The main tanks already have them (for being loaded via the SH). And if you transfer the tanks using a robotic arm, you have to add the weight and complexity of the arm. If not, it's a big, dangerous, time-consuming EVA job. "Best part is no part."

3. It's heavier. This is an upper stage. Every kg of structure is a kg less to orbit. Strap-on boosters are acceptable because they are dropped so early during the launch.

My point is that it's more cost evective to only send the necessery to space which in our case is the fuel, sending the ship and get it back to earth is unessery if you could only send the fuel (and of course lightweight and cheap package) .

For the issue of rendezvous and connecting, I suggest the use of a flexible pipe like those used for air refueling which will use small thruster to move, once attached to the tank they will start suck the fuel or they will retract to connect the tank directly to straship. no plumbing needed just an orifice in the tank.

[RonM]

Hi everyone, I did love the idea of Starship refueling another Starship but I was thinking about a simpler way to get extra fuel by mean of attaching external  tanks (cheap, disposable)  to  SS that will rendezvous somewhere ? think it simpler than later concept that still  has to be proven.

Sure, the aft cargo pods could be made into tanks without hurting the ascent aerodynamics, but:

1. It's not that unproven. Progress tanker/cargo craft have auto-docked with Salyut-6, MIR and ISS 100+ times. Not to mention all the air-to-air refueling going on every day.

2. It's not that much simpler. Those tanks would each have to have connectors, valves, plumbing and sensors. The main tanks already have them (for being loaded via the SH). And if you transfer the tanks using a robotic arm, you have to add the weight and complexity of the arm. If not, it's a big, dangerous, time-consuming EVA job. "Best part is no part."

3. It's heavier. This is an upper stage. Every kg of structure is a kg less to orbit. Strap-on boosters are acceptable because they are dropped so early during the launch.

My point is that it's more cost evective to only send the necessery to space which in our case is the fuel, sending the ship and get it back to earth is unessery if you could only send the fuel (and of course lightweight and cheap package) .

For the issue of rendezvous and connecting, I suggest the use of a flexible pipe like those used for air refueling which will use small thruster to move, once attached to the tank they will start suck the fuel or they will retract to connect the tank directly to straship. no plumbing needed just an orifice in the tank.

Lightweight cheap packaging that can survive launch isn't possible for cryogenic propellants. This "package" will be the same construction as the SS propellant tanks, so why not skip the "middleman" and use SS tanks?

[spacexfanatic]

Hi everyone, I did love the idea of Starship refueling another Starship but I was thinking about a simpler way to get extra fuel by mean of attaching external  tanks (cheap, disposable)  to  SS that will rendezvous somewhere ? think it simpler than later concept that still  has to be proven.

Sure, the aft cargo pods could be made into tanks without hurting the ascent aerodynamics, but:

1. It's not that unproven. Progress tanker/cargo craft have auto-docked with Salyut-6, MIR and ISS 100+ times. Not to mention all the air-to-air refueling going on every day.

2. It's not that much simpler. Those tanks would each have to have connectors, valves, plumbing and sensors. The main tanks already have them (for being loaded via the SH). And if you transfer the tanks using a robotic arm, you have to add the weight and complexity of the arm. If not, it's a big, dangerous, time-consuming EVA job. "Best part is no part."

3. It's heavier. This is an upper stage. Every kg of structure is a kg less to orbit. Strap-on boosters are acceptable because they are dropped so early during the launch.

My point is that it's more cost evective to only send the necessery to space which in our case is the fuel, sending the ship and get it back to earth is unessery if you could only send the fuel (and of course lightweight and cheap package) .

For the issue of rendezvous and connecting, I suggest the use of a flexible pipe like those used for air refueling which will use small thruster to move, once attached to the tank they will start suck the fuel or they will retract to connect the tank directly to straship. no plumbing needed just an orifice in the tank.

Lightweight cheap packaging that can survive launch isn't possible for cryogenic propellants. This "package" will be the same construction as the SS propellant tanks, so why not skip the "middleman" and use SS tanks?

If Spacex envision to make reusable spacecrafts with 4mm thin stainless steel, it won't be that hard to imagine a fuel tank that goes to space with the same mensurations and with the same materials.skiping   the "middleman" may save weight and money.

[Redclaws]

And now you’re discarding that item.  It has engines and avionics on it, doesn’t it?

[spacexfanatic]

And now you’re discarding that item.  It has engines and avionics on it, doesn’t it?

Engines and avionics like those in satellites.