5 ms·
I'm the lead roboticist. Within bounds, I can answer questions.
by GlenTheMachine 2mo ago
I'm the lead roboticist. Within bounds, I can answer questions.
- walrus01 2mo agoIt sounds like each "MEP" (mission extension pod) once attached is its own fully autonomous satellite? How big is each MEP? Like, a mini fridge? Since the mission is designed to attach one and then leave to go to another satellite that needs servicing?
- GlenTheMachine 2mo agoSort 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.
- sidewndr46 2mo agosure seems like this could just as easily be used to perform on-orbit disassembly of a hostile nation's satellite?
- JumpCrisscross 2mo ago> on-orbit disassembly of a hostile nation's satellite? Too complicated for disassembly. But totally valid for modification.
- bespokedevelopr 2mo agoYes, 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-between-peaceful-and-provocative/ https://spacenews.com/chinas-orbital-maneuvers-blur-the-line...
- aqfamnzc 2mo agoI would think there are much less expensive and more rapid methods of "on-orbit disassembly" than a system like this?
- ceejayoz 2mo agoNone of them can drop nice deniable limpet mines that go off much later, though.
- ben_w 2mo agoIf I was going to attempt that, instead of a complex repair bot, I'd be asking if the combination of a Raspberry Pi Pico, minimal sensors/comms, small ion drive, and PV can be made smaller than whatever the tracking radar's wavelength is. Launch thousands in one go in a big boring-seeming box, to a completely different orbit, release the pies and let orbital velocity do the damage on impact. (Actually hitting is of course hard, even under power, but on the other hand if you miss you get to re-use the same impactor for another attempt perhaps every 47 minutes depending on the orbit).
- spieswl 2mo agoAbsolutely, although it's a different ball of wax if you're trying to do RPO of this complexity with an adversarial body.
- adolph 2mo agoWhat sort of interesting actuators are used that people might not commonly think of? (I'm thinking of interesting solutions like the JWST's mirror actuators [0].) 0. https://hackaday.com/2022/02/08/working-model-reveals-amazing-engineering-of-webbs-mirror-actuators/ https://hackaday.com/2022/02/08/working-model-reveals-amazin...
- GlenTheMachine 2mo agoWe use pretty standard BLDCs.
- iagooar 2mo agoWhat is your story, how did you get into robotics? Was it your first choice?
- GlenTheMachine 2mo agoOh 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.
- detritus 2mo agoPleb here: the very fact you were able to eke a hexapod robot in the late 80s from OTC technology is super impressive. Just following your dialogue here enforces why I love HN comments x
- spieswl 2mo agoSalute to a real robotics veteran. I can't imagine the hardware gore you have seen.
- notahacker 2mo agoIs there a paper somewhere describing the intended robotic operations and robotic toolkit it's equipped with (beyond the MEPs, though they're pretty interesting too)? (context: some of my colleagues and consortium partners are working on European projects involving end effector toolkits for orbital [dis]assembly and slot-based electric propulsion ORUs respectively. Would love to chat but suspect you're pretty busy!) Congratulations on the launch.
- GlenTheMachine 2mo agoThanks! 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.
- notahacker 2mo agoCool. Is there an IAC paper in the works as well?
- spieswl 2mo agoWhat software are you all using for kinematics and dynamics calculations?
- GlenTheMachine 2mo agoIt’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.
- SegfaultSeagull 2mo agoCan you tell us what is out of bounds, so we know not to ask those questions? :)
- GlenTheMachine 2mo agoI 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.
- lenerdenator 2mo agoHow could this be applied to grab old satellites (of which there are, to put in in technical terms, "too damn many") out of orbit and bring them back to Earth for processing? Seems like some of the technology could be used to recycle space junk.
- GlenTheMachine 2mo agoIt'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.
- notahacker 2mo ago> So, nobody will be recycling space debris that lives at GEO any time soon, unless someone figures out how to do it in situ. Actually have a funded project looking at this, albeit only parts of the chain and only to TRL4. The trick is being able to turn enough of the orbital mass into solid propellant, which at least in theory makes manoeuvring around GEO graveyards collecting stuff to take to your orbital recycling plant net positive. After that it's only building a complex processing chain for raw materials under space systems engineering constraints and finding some end customers to worry about ;) Want a rotary multitool and laser cutting end-effectors (with or without the Sener interface) for the next mission?
- fragmede 2mo agowhat's it like working with robot arms with that kind of latency? Any AI stuff (ML models etc) on board?
- GlenTheMachine 2mo agoThe RPO and docking are autonomous specifically because it's hard to deal with the latency. Note that the algorithm stack for almost any spacecraft cannot rely on modern compute. Single-core sub-1 GHz processors are the standard. Very few GPUs have ever been in space, in any capacity, and none that I know of in a mission-critical role.
- electroweak 2mo agoWould this be able to boost Hubble or replace it's gyros? Does the satellite servicer need its targets to be constructed to some common standards, or is the new capability now leading to common standards? Was it built with a method for itself accepting refueling? It seems to me this device would lead to a revision in satellite reliability design and life calculations.
- GlenTheMachine 2mo agoIt's very likely that a spacecraft similar to MRV/RSGS could do a life extension mission on Hubble. But, unfortunately, Hubble is in a very different orbit than MRV/RSGS is, so we wouldn't be able to reach it. "Does the satellite servicer need its targets to be constructed to some common standards, or is the new capability now leading to common standards?" We can do life extension missions on client spacecraft that were not designed to be robotically compatible. That's actually SpaceLogistic's primary business case. The question of standards in the spacecraft industry is a huge question. It's being worked... by a lot of people, cue the obligatory XKCD reference. "Was it built with a method for itself accepting refueling?" We are, in fact, refuelable. "It seems to me this device would lead to a revision in satellite reliability design and life calculations." We hope so! Spacecraft are expensive in large part because they have to be designed to be incredibly reliable. The example I use is cars. If you had to design a car that could go for half a million miles without ever having a part replaced, you could. It would just cost a billion dollars. But that's how we design spacecraft today. IF we can create a "mechanic safety net", we might be able to bring the cost down significantly.