I can only provide answers to technical or programmatic questions that have already been "approved for public release" by DARPA and NRL. We've done a number of publicly released presentations over the years, so there is a fair amount of that information in the public domain, but things like the exact algorithms we use for IK or controls, or whatever, hasn't been released yet. I also can't speak about anything that is Northup-Grumman's or SpaceLogistics' intellectual property or is business sensitive, so I can't say which client satellites we'll be servicing.

I'm very hopeful that I'll get a strong technical paper through public release by the end of the year, ant at that point I could provide more detailed technical answers to things a HN audience would be interested in.

Thanks! There isn't a paper yet, but I'm working on one; I hope it will be presented at the upcoming iSAIRAS/iSpaRo conference in Cologne.

It’s all custom flight code. The only software packages we use are basic matrix-vector libraries. Hopefully there will be a paper describing the dynamics/kinematics/controls algorithms soon.

Sort of mini-fridge sized. They take over attitude control and propulsion for satellites that are low on fuel.

"Since the mission is designed to attach one and then leave to go to another satellite that needs servicing?"

Yes.

Oh gosh.

I grew up in the middle of nowhere Virginia. Like many of you I was a nerd, and I had no outlet for that nerd-dom until I spent all summer working for money to buy a C64. I taught myself assembly, and was a high school intern at NASA Langley where I learned about parallel processing, was introduced to the idea that people would actually pay you money to program computers, and had a tour of their space robotics lab.

When I went to college the guy two doors down from me in the dorm decided he wanted to build a robot, and he recruited me because I knew how to code. We spent freshman year working on a six-legged frame walker which we dreamed would explore Mars someday (this was in the late 1980s, long before the first Mars rover). It didn't work for crap -- the late 1980s were a disaster for makers, we had to source everything from the hardware store or Radio Shack. It was also the most amazing thing I'd ever done, and from then on I was an aspiring space roboticist.

I managed to not fail out, but it was close.

I went to grad school at the University of Maryland's Space Systems Lab under Dave Akin ("Akin's Laws of Spacecraft Design"), where I learned control theory and a ton of hands-on skills and got to scuba dive supporting the development of Ranger, which could have been the first US satellite servicer except we could never find a launch for it. I graduated with a PhD in aerospace engineering in 2003, and got hired by NRL, where I worked on RSGS.

It's almost impossibly hard to return things to earth from GEO. Robert Heinlein famously wrote that "a circular orbit is halfway to anywhere", which means that the most energetically difficult part of a mission to the Andromeda Galaxy is getting out of earth's gravity well.

To get back into earth's gravity well from a circular orbit requires similar amounts of fuel. Getting things back to earth from low earth orbit is doable, if you have a heat shield, because you only have to dump enough velocity to start hitting the atmosphere, and atmospheric drag does the rest of the work.

But that doesn't work at GEO, because you're so high (22,000 miles as opposed to ~1,000 miles for LEO). It's very hard to get enough delta-V (read as "change in velocity", which is basically the amount of fuel you need per unit mass) -- you'd need something with as much fuel as the upper stage of the rocket you were launched on, plus you'd need a heat shield. Alternatively you could use electric propulsion, which takes a lot less fuel, but would also take, literally, a couple of years, during which time you're a hazard to navigation to anything in a lower orbit. Plus, electric thrusters of the size you'd need to do this aren't cheap either.

So we basically never do that. If you need to dispose of a derelict satellite at that altitude, it turns out to be much easier to raise its orbit by a few thousand kilometers.

So, nobody will be recycling space debris that lives at GEO any time soon, unless someone figures out how to do it in situ.

Yes, China demonstrated this capability a couple year ago with towing a geo sat to a different orbit. It only makes sense to go tit-for-tat on these capabilities for servicing and the unspoken offensive ability.

https://spacenews.com/chinas-orbital-maneuvers-blur-the-line...

Absolutely, although it's a different ball of wax if you're trying to do RPO of this complexity with an adversarial body.

> on-orbit disassembly of a hostile nation's satellite?

Too complicated for disassembly. But totally valid for modification.

I would think there are much less expensive and more rapid methods of "on-orbit disassembly" than a system like this?

We use pretty standard BLDCs.

The new robot grappler arm definitely seems like an advancement on previous designs. The MEV was, as I recall, designed to mate with only a specific set of models of geostationary satellite bus and, for lack of a better term, ram a probe up its backside to grab onto it.

the probe ramming: https://www.youtube.com/watch?v=vJZ3xmuom0M

One of the things that people who don't pay attention to space based infrastructure find odd, if you tell them, is that in the entire history of manned spaceflight no human has ever gone to geostationary orbit.

Presumably it's also known to everyone who builds/operates these that having a foreign nation's military satellite intentionally approach your own geostationary satellite to within a very short distance, as the vast area up there goes, is a very thinly veiled threat or demonstration of capability.

https://www.google.com/search?client=firefox-b-d&q=russian+s...

Outside of GEO, nobody in the public really knows what the X-37 does when it's in orbit, but one of the theories I have seen thrown around is that it's capable of approaching and inspecting other things in LEO, or theoretically even grabbing or manipulating one in some way.

As I understand it, the current on-orbit service functions include... orbit manipulations.

Any service functions of existing equipment would depend on charge interface or communications functions that are not exposed or standardized.

It will make a good season to practice kinetic adjustments until the fleets start shipping terminals for Astromech droids.

But why isn’t it called WARPA now?

DOGE got DOGE'd itself. It doesn't exist anymore.

Defense doesn’t get DOGE’d, only programs that build up communities do. There’s always budget for more destruction.