Is 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!)
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.
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 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.
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.
How 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.
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.
What 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].)
Is 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.
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 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?
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.
Can you tell us what is out of bounds, so we know not to ask those questions? :)
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.
What is your story, how did you get into robotics? Was it your first choice?
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.
Salute to a real robotics veteran. I can't imagine the hardware gore you have seen.
Pleb 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
What software are you all using for kinematics and dynamics calculations?
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.
sure seems like this could just as easily be used to perform on-orbit disassembly of a hostile nation's satellite?
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.
I would think there are much less expensive and more rapid methods of "on-orbit disassembly" than a system like this?
> on-orbit disassembly of a hostile nation's satellite?
Too complicated for disassembly. But totally valid for modification.
How 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.
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.
What 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-amazin...
We use pretty standard BLDCs.
what's it like working with robot arms with that kind of latency? Any AI stuff (ML models etc) on board?