26 thoughts on “The Need For Responsive Space”

  1. Responsive space is a desire of the military. It is rendered moot by build large, robust constellations of satellites, not a handful of billion dollar “Battlestar Galactic” bespoke satellites. Equatorial LEO is almost completely useless for military purposes.

      1. No, an equatorial orbit in LEO can only see a couple hundred miles north and south of the equator. Not much there of military interest. It takes way too much energy to launch into low inclinations and move to high inclinations. A 60 degree inclination change takes as much Delta-v as launching into orbit in the first place.

        1. The point of a base in ELEO is not to see things of military interest. We see things of military interest with reconnaissance satellites. The purpose is to be able to rapidly respond when things of military interest are seen.

          It is more efficient to launch to ELEO than to any other orbit if you launch from ocean platforms at the equator. When propellant is cheap, delta vee is cheap. If propellant is ten bucks a pound in ELEO, I can toss twenty tons to ISS from there for a few million bucks, and do it within a couple hours (ignoring phasing issues when I get there). Falcon 9 is sixty million, and has to wait for a launch window (and perhaps weather).

          1. From ELEO, what could they do to respond? Fast response requires being where you’re needed, and that isn’t over the equator.

          2. Over the equator is a hell of a lot closer than sitting on a launch pad, waiting for launch window that might be hours away. In ELEO, you go through every orbit plane in cislunar space (and particularly in LEO) every hour and a half. When the nodes cross, do a plane change, and you’re in that orbit. Then it’s just a matter of how much propellant you want to use for phasing to rendezvous.

          3. Plane changes, especially from LEO, require a tremendous amount if delta-v. Like I mentioned before, a plane change of 60 degrees requires the same amount of delta-v as was required to launch it in the first place. That means that if you’re using chemical propellants, you’d need many tons of propellant to accomplish the maneuver. If you’re using electric propulsion, it would take months to years to complete the maneuver. Neither option makes any military sense. But what do I know, I only used to operate military satellites.

          4. I have done orbital mechanics for a living, and am well aware of the cost of plane change in delta vee. I have also run the numbers, and if propellant is cheap, it’s much faster and less expensive to plane change from ELEO than to do a dedicated launch.

      1. Not quite sure that necessarily works. There a lot of vectors to attack can’t defend against them all and some may have no defense. Now maybe you have excessive redundancy and superiority but at that point, you can nearly do it anywhere and rapid launch will be cheaper.

        1. There is no such thing as “rapid launch” in the context we’re discussing, and there is no way it would be cheaper. To think that there is is to display profound ignorance of orbital mechanics.

          1. For example if the adversary can set up a mass driver(eg Spinlaunch) the ELEO is a sitting duck and if they can place it on the equator it can quickly become useless. Unless you have defense against retrograde debris fields in ELEO. Setting up the ability to Launch from anywhere I have to imagine is cheaper than defending a sitting duck orbit or having so much redundancy in that orbit..

          3. I told you before I am the kind that knows the difference between Alternating Current and Direct Current unlike some around here. You don’t want to say why this is stupid ?

        1. Sufficient infrastructure is multiple daily flights to ELEO of fully reusable space transports, reusable refuelable space tugs, and propellant depots.

          1. So about the same scale as Musk is talking about for his City on Mars project. With a flight rate doubling time of two years, that would take about 25 years to build up, which is essentially what I meant by “medium term.” Absent the Mars project, what would drive the infrastructure buildup?

            Did you write the white paper you mentioned the last time we talked about this? I really wanted to read it, and try to follow along with your reasoning and math. It’s plausible, given a prime mover such as a Mars project, but what else? Cisjovian industrialization was something I always thought would do it.

  3. Rand, how about polar LEO? It covers all the surface every few orbits, and gives a clear field of fire to all sats in any orbit.

    1. Which “polar LEO”? There are an infinite number of them. A “clear field of fire” with what? How often will there be a conjunction with a given polar LEO orbit and a satellite in some other orbit?

      Anyway, we’re not talking about shooting at satellites. We’re talking about intercepting them, or doing space rescue.

  4. Not sure what talking about, but I will give it a whirl.
    Let’s say got two cylinders, which are 20 meters diameter and 100 meter long and attached with 6 ropes 500 meter long. So one of them is 500 meter closer to Earth, and there is gravity gradient. And it’s at 500 km elevation above Earth.
    The ropes can be detached, leaving two cylinder to go separate ways. And 3 of 6 can handle the load of gravity gradient.
    And you have stuff in cylinders.

    1. At 500 km in LEO it would/should have less radiation than ISS. And less drag.
      It seems you might want it, higher, assuming there isn’t as much radiation as ISS.
      Not sure what elevation is equal to the radiation ISS gets.
      Anyhow could go even higher and have enough radiation shielding.

  5. Electronic jammers and/or lasers to disable or destroy the offenders. Several stations in polar orbit would give them several views per day at any target in cis-lunar space. Observation and rescue is a necessary capability. But I have yet to read about a successful military outfit that didn’t have armed backup.
    Have a trash collector in each of several orbital levels for cleanup.

  6. There is a form of responsive launch available and deployed right now. I mean, what’s a solid fuel ICBM if not an example of responsive launch? The problem with us using it is you’d need to allow overland launch to hit fast access targets. When you’re having a nuclear war, that’s not so much of a concern, but otherwise… You could build an ICBM field in south Texas that could launch along any great circle azimuth to cover any target on Earth in 45 minutes. Maybe put FOBS warheads aboard, then swap out for spy gear if you needs to take a quick look at something.

    I still think you’re underestimating the cost and time for the infrastructure you’re talking about near term. Those sea launch platforms are never going to be cheap, and while you could build a Battlestar with space tugs aboard, would you be able to have the proper mix of responsive launch payloads aboard too?

    And the reason I say near term is because all this stuff is going to go away middle term (say in a few decades, at most). We’re just catching up after our “betters” were allowed to squander an entire human lifetime (mine, unfortunately). Near term, you might be better off (cheaper, at least) building three Deathstars in GEO, equipped the best possible optical and electronic snooping gear. No one would be able to sneak up on them either, so they could defend themselves with missiles and lasers.

    1. There is this too. Which far more inline of what the article writer is recommending. That in a conflict that has removed carnival that we need emergency launch capability anywhere. Though the payload capability would limit the replacement capability.

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