Some Words About Last Night

I ended last night's post on SpaceX achieving yet another reuse record with a photo that caught a Falcon 9 seconds after lift off, while the booster from the mission a week before was being moved from the recovery drone onto the truck for transport to where it will be inspected and prepared for it's next flight.  I said, "in my mind, the way it ought to be."  This is not so much about the launch cadence of once a week, which is the only place in the world trying for that.  It's about the reuse of the hardware. 

I've only worked on the design of a few satellites, and really only one I can talk about by name and mission, back between about 1990 and 1996.  As a receiver and PLL synthesizer designer, I worked on those parts of satellites.  I believe the things I'm going to talk about apply to rockets and their hardware, both electronic and mechanical, but I never worked on a launch vehicle.  

Those who aren't familiar with the design world probably don't know this, but the price of the parts you buy depends on the conditions the parts are rated to work under.  The cheapest electronic parts are the plain commercial grade parts; they're rated for a narrow temperature range, from 0 to 50C, or 32 to 122F.  These are what are used in consumer devices of all kinds including inside the passenger compartments of cars.  There are three more stringent selection grades and each grade is more expensive than the one before: industrial (often -40 to +80C), Military (-55 to 125C) and then Space rated, or Class S.  There are others for really severe environments, but these are the main ranges.

Everyone who works on space hardware knows that the requirements always specify the most expensive parts made.  Class S parts are generally screened and tested to the same temperatures as military, unless there are requirements for that specific mission that go beyond those, and are also rated for their ability to survive radiation in space.  

 

It's important to say that there could be no difference between the silicon that makes up two parts, one commercial and one class S.  They can be made side by side on a wafer and one gets more tests and documentation than the other.  It's the difference in testing to guarantee the performance that raises the price.  That's why I think it's fair to lump things like engine turbopumps and processors; they're both the best parts because of the things done to guarantee they are.

To me, a very reasonable question goes something like "these are the best parts in the world and we throw them out after one use?"  We invoke these requirements to ensure that these very expensive satellites (or manned capsules), being lifted into orbit by even more expensive boosters, all perform their mission.  Most transistors or more complex circuits will run virtually forever, if you run them a bit below their absolute maximum ratings, but we throw these out after a few minutes of use?  Remember, Voyager has been running since 1977 - and those are probably 1973 vintage parts which ran for hundreds of hours in ground testing.   

We throw these out because "old space" never seriously asked the question of how much more work they would have to do in order to recover a booster, or how much capability they throw away on every mission.  They never really seriously contemplated "how can we do this?" because they never seriously thought there was a need to reuse boosters.  Congress was apparently happy to keep paying them whatever they billed for any launch vehicle - look no farther than SLS.  A week ago, I opined,

I've long thought that the way SpaceX developed the technology was brilliant.  I could see from the way ULA CEO Tory Bruno talked that he thought it would cost way too much money to develop and he just saw the costs entirely differently.  SpaceX seemed to think that they sent up a Falcon 9 for hire and when the booster separated, it had just been thrown out.  It's now "free" as if they picked it out of a trash pile to experiment on.  They can tell the engines to turn on for a very minimal amount of extra cost, and guide it to where it could land.  As long as the primary mission of launching a customer's satellite was accomplished, and every launch coverage has stressed that was their crucial part, everything after MECO was teaching them more than if they dropped the booster in the ocean.  True, the recovery drones were an expense and there were others, but those costs get amortized out over many recoveries - well over 100 at this time.

There's a Netflix documentary coming on the return of manned spaceflight to the US through SpaceX Crew Dragon and the story of getting there. There's a line in the trailer about how SpaceX changed the industry.  I would say they didn't simply change the industry; they changed everything.  The rest of the industry just hasn't learned that, yet.

Which raises the real question that if they can do 12 launches on one booster, how many more before it becomes too expensive to refurbish for reuse?  20?  Who knows?  Don Rumsfeld's quote about having known unknowns and unknown unknowns comes to mind. Last summer, Elon Musk was openly talking about boosters being launched 20 or 30 times, maybe up to 100 times, with periodic maintenance like commercial airliners get.  It's the dawn of a new age - the one promised to us 60 years ago.

B1051 after her 10th flight and arrival at Port Canaveral, two flights ago.  Richard Angle photo for Teslarati.