28 thoughts on “Space Rescue”

  2. Calculate how much propellant would be required to move a Crew Dragon capsule from an equatorial LEO to rendezvous and dock with the ISS, them get back to us.

    1. With propellant at twenty bucks a pound in ELEO, it’s cheaper than a Falcon 9 out of the Cape, and more responsive, since you can do it within an hour or so if it’s a direct plane change, longer if you do a bi-elliptic, which would be cheaper. To get to ISS out of the Cape, you have to wait for the plane to line up, which could be up to twenty-four hours.

      2. You’re not showing your numbers. You’re just stating an opinion. Go ahead and actually calculate how much propellant it would take to execute the maneuver.

        1. I’ve done it. From a briefing I put together for the Space Force:

          Falcon 9 can deliver ~20 tons from the Cape to ISS orbit at 52 degrees for ~$60m
          Assume stage fraction of 10% (ratio of structural mass to fueled mass) and 25k feet per second (fps) circular velocity, 480 seconds Isp
          Delta V from equatorial to 52 degrees is ~22k fps
          Mass ratio is ~4.2, requiring ~200k lbm of propellant
          At $20/lbm in ELEO, marginal mission cost is $4m
          Even less with bi-elliptic
          Even less with low-thrust transfer

          1. Now, factor in the propellant needed to launch from the US and to place the propellant into an equatorial orbit. Also, your Isp of 480 is a bit high even for LH/LOX. The only launcher that would be able to launch 200k pounds of propellant doesn’t use LH/LOX, and maintaining an on-orbit fuel depot for that combination is even more difficult than liquid methane/LOX.

          2. The propellant will not be launched from the US. It will be launched from the equator. There will be orbital depots in ELEO that can minimize boil off. 480 Isp is a perfectly reasonable one for a space-based tug, but if you want to use a lower number, it’s still cheaper than a Falcon 9 from the Cape by an order of magnitude. This is a completely different space-transportation infrastructure than the existing one.

          3. OK so I’m going to theorize here a bit, if you are basing your comparisons on Falcon 9 out of the Cape, I’m assuming you are relying on a Crew Dragon as a rescue vehicle?

            Your price figures have to be computed for RP-1/LOX because if it’s just a Crew Dragon at ELEO relying on NTO and MMH I’m seeing figures more in the $200/lb category assuming it even has enough thrust and ISP to get to ISS in less time than from the Cape. So I’m thinking what you are thinking is a Falcon 9 Second Stage w/Crew Dragon there with the ability to be refueled manually at the ELEO base? RP-1/LOX gets you in the $20/lbm range. Assuming you only need to top off occasionally? Or maybe you use longer term larger tanks at the rescue station?

            Pardon my lack of aerospace-fu. Just trying to get a more clear picture of what you envision.

          4. No, I said twenty tons to the orbit. The rescue vehicle would probably be less mass than a Crew Dragon, because it has no entry or recovery capability. I’m just pointing out that it’s cheaper and faster to get anywhere in cislunar space, including any LEO, from ELEO, than from a terrestrial launch site.

          5. From article: “While Osburg says any Space Rescue Service might be a decade or more away, the key is to start planning now — and Rand, he emphasized, is not attempting to take responsibility or to say that it would have all the answers about how to implement such an idea. ”
            –Larry J
            December 5, 2023 at 4:16 PM

            Now, factor in the propellant needed to launch from the US and to place the propellant into an equatorial orbit.–

            Need launch site at equator, then first launch from Equator, later put rocket fuel in equator orbit and go quicker from orbit. Meanwhile launching from equator on Earth, can launch point to point anywhere on earth surface.

            What you need is cheap floating breakwater, which provide good surfing. So for the surfing, 20 meter diameter balloon tank filled with freshwater, which will float low in the water and break all waves. One can have smaller diameter breakwater for just stopping all waves.
            The 20 meter diameter uses less than 1 ton per meter length and would use thin walled titanium which doesn’t corrode in sea water.
            And you put rubber mat on it, so as make hard for surfers to hurt themselves.

          6. The 20 meter diameter thin walled pipe which 200 meter long would have about 120 tons of high strength titanium. Each meter in length displaces about, 320,442 kg of sea water, times
            200 is about 64000 tons of seawater. And freshwater within it would pressurized to about 10 psig and has mass of about 62830 tons.
            And floats about 1 meter above waterline.
            And you put it in relation to waves, so it get best surfing. Then have smaller diameter and much longer breakwater. So 12 meter diameter or smaller and thinner walled than 20 meter diameter. Therefore one make more than 1 square km of ocean area without waves. Or make square km of ocean water be usable “real estate”.
            Vehicle traffic within area and wind would create some waves over larger areas within it, but such small waves can have very small localize breakwaters to get waves down small ripples.

  3. Or launch from Isla Pinta, Galapagos, Ecuador (0.5869436889730313, -90.75172946919584)

    Even has a nice little caldera for the evil overlords lair…

    1. Now factor in ITAR. It’s like the saying, “For every problem there’s an answer that’s simple, obvious, and wrong.”

        1. Your equatorial LEO idea is nonsense. A satellite’s orbit is driven by its mission, and there are very few missions for a satellite in an equatorial low earth orbit. It’s really a dumb idea based on a flawed precept that the cost of propellant is more important than operational utility.

          1. It’s not about “missions.” It’s about infrastructure. In the future, things like space assembly hangars, way stations, propellant depots, tourist resorts, military bases (including Space Guard) will have no need to be at higher inclinations. ELEO will be a natural harbor for most human activity, and if things need to be in other inclinations, it will be cheaper/faster to get them there from ELEO than from traditional spaceports.

          2. Can we agree that 51 degree ISS is in a dumb orbit? And shouldn’t have future space station at that orbit?
            And probably within 7 years, ISS won’t be in orbit?
            And a lot people live nearer to the equator and within 10 years, India could become a lot more involved in doing things in space.

            Suppose the Moon has mineable water.
            I think main significant thing about it is it could start a market for water and rocket fuel in space. So, water and rocket fuel in made in space and going to ship it to Earth orbit, what Earth orbit will get shipped to, the most?

          3. A satellite’s orbit is driven by its mission, and there are very few missions for a satellite in an equatorial low earth orbit.

            Very few missions? Like say space rescue?

            It’s really a dumb idea based on a flawed precept that the cost of propellant is more important than operational utility.

            Wouldn’t be the first time cost of propellant was more important. I find this assertion weird given you wrote earlier:

            Now, factor in the propellant needed to launch from the US and to place the propellant into an equatorial orbit.

  4. No, I said twenty tons to the orbit. The rescue vehicle would probably be less mass than a Crew Dragon, because it has no entry or recovery capability. I’m just pointing out that it’s cheaper and faster to get anywhere in cislunar space, including any LEO, from ELEO, than from a terrestrial launch site.

    Twenty tons to orbit (aka ~40,000 lbs) is about twice the mass of a Crew Dragon with trunk. So you envision the rescue “station” with a rendezvous/docking orbiter that can take people from a damaged ISS to elsewhere but not bring them down from orbit?

    Wouldn’t it be better to do be able to return from orbit? Dragon 2 is essentially capable of that already w/o expertise.

    There is probably much that can be done with F9/Dragon already if there were an emphasis to do more. A guy like Isaacman could contract a lot out of SpaceX today and get things done w/o everything depending upon NASA or Starship.

    2. If there is a need/desire to return from orbit, they would do that after getting back to ELEO, on the next scheduled flight. Again, this is a world in which there are daily (or more often) flights to and from ELEO by Starship or other space transports. Capsules would be pretty much obsolete.

    3. Speaking of rescue:

      A guy like Isaacman could contract a lot out of SpaceX today and get things done w/o everything depending upon NASA or Starship.

      Like extending the life of the Hubble Space Telescope. I sure hope he (or someone) is able to pull of this off in conjunction with NASA/SpaceX. The upcoming Polaris Dawn mission in 2024 with planned EVA would be a good trainer mission. This should be more than just free floating around on a tether in a spacesuit, but include pulling stuff out of the trunk and putting it back and working with power tools.

  5. Can we agree that [the] 51 degree ISS is in a dumb orbit?

    Not for my 20,000 LED Solar Powered Coca Cola Orbital Advertising Campaign it’s not.

    2. Can we agree that [the] 51 degree ISS is in a dumb orbit?

      Absolutely. As far as I’m concerned, it’s “54 40 or fight!”

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