I’m just a few chapters in. SpaceX is not the subject here, but is part of the backdrop. It’s about the generation of companies that came after SpaceX proved that it was possible to do things differently.
Pete Worden plays a significant part. I hadn’t heard of him before, but he ran NASA Ames for a while and cultivated an unconventional environment there, which included pushing low-cost missions to the moon. Senator Richard Shelby hated that as it possibly meant projects moving out of his districts.
Curiously, I unknowingly had some minor connection to this. There’s a whole chapter on the “Rainbow Mansion”, which I went to a while back for a Yuri’s Night (dressed in a cubesat costume). I knew the mansion was somehow connected to NASA, but it was the exact band of “misfits” that Worden promoted that lived there. Sort of a weird co-habitation thing, but it seemed fun. I probably ran into Worden there but don’t recall specifically. Our cubesat was the first crowd-funded satellite and we possibly spread some ideas then.
Worden seemed to polarize NASA Ames into two camps that either loved or hated him. With the anti-camp hating him so much as to submit a report to Congress that Worden, Barack Obama, Elon Musk, and Lori Garver were involved in a (Chinese?) conspiracy to destroy the US space program. It was all completely ridiculous, but that didn’t stop them from causing problems (like one of Worden’s people being held for questioning by the FBI).
ISTM for large stuff, a simple lasso is best. The tether itself exerts very little tug on on whatever it has lasso’ed. Satellites are bristling with stuff that stick out n all directions. Rather none of it is stout, but all of it is attached at least a little bit.
Lasso’s don’t work for small hunks of debris or random crunched up shape. But IMO nothing works for them because they’re simply too numerous the track down and target individually. You still need to “fly” another satellite into co-position & co-velocity rendezvous. That will always be energetically expensive. Whereas post impact junk is in chaotic orbits every which way.
Like so many kinds of pollution, it’ll cost billions to clean up what could have been prevented for thousands. But as long as the people saving the thousands don’t get billed for the billions, they’ll keep doing it and we’ll keep paying for any cleanup that does ever happen.
The co-velocity energy requirement could also theoretically be dealt with by using a more sophisticated tether, powered by a solar array. The rest of the positioning would take fuel, though. Fuel and a stock of disposable tethers would both increase the cost and limit the useful service period of clean-up drones. (It’d be handy to have a fuel depot up there, and not just for projects like this.)
Not sure I follow. Or perhaps we’re talking about two different phases of the de-orbit. Here’s my take, and I’d appreciate hearing yours in more detail too …
To attach the tether you need to drive your janitor bot up to the orbiting target to both nearby in space and nearly co-velocity. We’re not going to be snaring these things while zooming past them at 100 km range and 2000ms-1 difference in velocity. More like 20m range and 1-2ms-1 difference in V.
Once we’ve lassoed the tether to the target, the janitor bot can release its end of the tether and drive off to the next target. Which will be chosen to be energetically nearby, but will also need a bunch of energy and time to sync up with that next one too. Lather rinse repeat until out of fuel, or expendable tethers or whatever other consumables the janitor has.
Your summary covers the process as I understand it. I was just saying that it should be possible to reduce fuel use by using an energized tether on the janitor bot to accelerate it. Incorporating solar-powered maneuvers reserves the bot’s limited fuel for velocity changes that require reaction engines. For example, I don’t think you can readily change orbital inclination with a tether, but you could raise the bot into a higher orbit with one.
I’m not practiced in orbital calculations, but say that the janitor bot and the next bit of space junk are in circular orbits, with the janitor at 1450 km and the junk at 1550 km altitudes, 3 degrees difference in inclination, and all other orbital elements already matched. Playing with some calculators and making some arbitrary assumptions (100kg fully loaded janitor-bot mass, ion thrusters with 1900s specific impulse, treating the two maneuvers as separate processes), I get a cost of 0.24kg of propellant to lift the janitor into the higher orbit and 1.97 kg to adjust the inclination (inclination changes are apparently very expensive in delta-v). For this particular maneuver, the tether would “pay” for itself as long as the apparatus masses less than about 12 kilograms, which is near the upper end of what you’d expect for a vehicle the mass of our janitor.
I hope that clarifies what I was aiming for. (And that my clumsy efforts at calculating orbital transfers don’t pain the experts in the thread too much.)
Your “clumsy efforts” greatly exceed my capability. But I do see and agree with your point.
In the early days of space, everything had to be simple. Nowadays we can build more complicated things. “Hybrid” propulsion systems that include old fashioned chemical reaction, solar-powered ion reaction, tethers, solar sails, and gosh knows what can be built. Whether they will be built is, as you suggest, a matter of whether the incremental power source & delivery mechanism can “buy” its way onto the vehicle in terms of mass, cost, mission duration improvement, etc.
My going-in thought is that the extremely passive approaches will tend not to find their way into orbital servicing just because they produce such tiny amounts of delta V that they mean the whole vehicle will take too long to accomplish any one intercept and de-orbit.
Taking 2 years to rendezvous with each successive de-orbit target is an unaffordable losing game. Rendezvousing with one every 2 weeks, even if the deployed tethers then take 2 years to accomplish the passive deorbit of those targets, still gets 26 things out of orbit for the cost of running one janitor for one year.
The assumption of course is that we’ll be janitoring the riskiest or largest ones first. We may never be able to clean up more than 10% by count, but if that gets the top 50% by risk of collisions or by value of the orbital slot(s) they foul, that’ll still be a net win.
The idea of sniping 23,000 (and counting) items is economically infeasible. We need some sort of shotgun approach. Maybe a fishing analogy is better. We need to trawl for our trash, not rod-&-line for it. Or at least for most of it; there may be a few high value items where rod-and-line sniping makes sense.
At high enough speed even small pieces of debris can cause a lot of damage.
NASA used to think that pieces of insulation falling off a shuttle during launch were no cause for concern – until the Columbia Space Shuttle disaster changed its mind.
Ideally, we’d eventually have a large fleet of very small janitor drones linked with a larger resupply depot, searching for and targeting trash semi-autonomously. (Even better if the system could move larger inactive vehicles into a “collection” orbit to be picked up for recycling, rather than deorbiting them, but that may be impractical even after we have manufacturing facilities in orbit.)
It’s not an international agreement, but in 2022, the FCC updated their rules on deorbiting plans, with the new rule set to go into effect for new vehicles in September 2024. The new rule requires provisions for devices launched to LEO under it to deorbit within 5 years of their end-of-mission date. [In the Matter of Space Innovation Mitigation of Orbital Debris in the New Space Age (PDF)] (Note that FCC documentation refers to satellites as “space stations”; I think this is because the FCC considers satellites as radio stations for purposes of regulation.)
Of course it would be nice to sweep up every fleck of paint, lost washer, and dollop of propellant. Can’t be done using any tech, not even SF imaginary tech.
So we’ll clean what we can affordably clean using the tech of the time. With luck the net progress of cleaning gets ahead of the net production of debris. And with luck we’ll avoid any early major collisions that set off a cascade before we can get the debris load back down below the Kesslerian tipping point. But …
As @Balance says just above, the good guys are agreeing to try to ensure they don’t leave end-of-life debris up there. But this is an international problem in an international commons and not everybody even bothers to try.
Much less succeeds. Malfunctions and explosions still happen at every altitude from LEO through cis-Lunar; orbiters brick themselves and can’t command their own designed-in deorbit.
All these agreements and efforts can have the effect of reducing the rate of debris growth as the in-orbit economy expands. But the early pollution of the mostly government / military space race to date will be with us for centuries and we’ll be working around it and trying to sweep up the easiest parts for centuries too.
Wish us luck; we’re going to need it. All of us. It’s both ironic and oh so human that the very first thing our nascent halting toddling steps into orbit did was pollute the shit out of the environment we hoped to exploit but could not yet use.
Well, SpaceX did it again. 2 successful launches (both with recoveries of the 1st stage) on the same day - 1 from Cape Canaveral (Starlink - stage recovery on drone ship), 1 from Vandenberg (Small Sat Rideshare - stage recovery on pad near launch site). 40 launches so far this year - all successful. Based on announced scheduled launches, it looks like they may make 70+ launches this year.
The cadence they are able to maintain is simply amazing.
236 successful launches out of 238 attempts (1 partial success, 1 full failure*) - The last 210 have all been successful.
200 successful recoveries of stage out of 211 attempts. The last failed recovery (as opposed to planned loss of stage) was in February of 2021!
My numbers include Falcon Heavy launches.
They did lose one other one during a pre-flight static fire test.
That’s pretty darn amazing. And also demonstrated that getting to where they are takes a) a lot of time and money, and b) a lot of exceedingly patient money.
Paradoxically we may be getting back to the late 1800s era of the solo inventor / entreprenuer a la Edison or Tesla only because our tech has gotten more complicated and slow-maturing than our hyperactive short-attention span finance industry can stand to fund to fruition.
I’m watching that in the UAM/AAM space right now. Easy for 20 contenders to get $100M angel funding each in a couple rounds. And all 20 run out of money 10% of the way to the goal. Impossible to get 1 contender the $2,000M = $2B of funding required to succeed. 'Tis a conundrum.
There does seem to be some element of the “big man” idea behind these rocket companies. Musk we know about. But the book I mentioned above mentions others. I’m through the section on Rocket Lab and Peter Beck. Beck has no college degree at all but built a hydrogen peroxide rocket bicycle, among many other things. Rocket Lab’s success seems to come in large part through sheer force of will on Beck’s part, though they certainly needed Silicon Valley VC money as well.
I’m almost through the chapters on Astra, which has had considerably less success than Rocket Lab. But again, the leader Chris Kemp seems to be driving it through force of will–though with significantly less engineering talent (he does have a partner, Adam London, that does have said talent–but it seems that a partnership is weaker than the all-in-one you get with Musk or Beck).
The last section is about Firefly. Given the pattern, and what I already know about their level of success, I expect them to be to Astra as Astra is to Rocket Lab. Just as much force of will, but even more insanity and less basic engineering. But in the end, they’ve also made orbit, so maybe determination really does matter more than anything else.
Of course, none of this says much about their chance of economic success. Rocket Lab seems most likely to survive, but SpaceX’s transporter missions are eating their lunch right now.
Sort of related to the thread topic is this article “A Rocket a Day Keeps the Costs Away”. I know that we’re not supposed to post links without summarizing the content so, as a brief summary this discusses the high operating costs of NASA vs NAZI Germany’s V2 program, during which “In the two weeks from September 18-30 1944, a total of 127 V2s were launched from five different launch sites.”
Notwithstanding the use of slave labour, which is acknowledged in the article, it does illustrate the possible, given extreme circumstances. It’s also interesting that, given that it was written in 1993, it kind of shows that something SpaceX-ish is possible.
At a super high level, there are two strategies to achieving low costs. First, what SpaceX is pursuing–total reusability. They have certainly driven vehicle costs down of their own accord, but they can afford a many-million-dollar rocket if it gets amortized over many launches. They are also going for capacity over launch rate (although they still manage to launch at an impressive rate).
The other approach is to make an expendable rocket as cheap as possible and mass-manufacture it. That’s what “A Rocket a Day” advocates and also what Astra is going for. They were shooting for a cost of $300k each, for a few hundred kilos to orbit. Is it totally crazy? Probably not; the cost of materials certainly isn’t the bottleneck. But the only way to get close to that is by increasing the cadence (i.e., the title of the paper), and they haven’t managed to come anywhere close to that. So it remains to be seen if anyone actually achieves what the paper suggests.
