Thursday, March 23, 2023

Relativity Terran-1 First Flight "a Successful Failure"

Relativity Space's video coverage last night, which they were calling part 3, began the same way as the first two attempts I watched.  When I turned on the coverage, it was T-25 minutes and counting. Then, just like every other one I watched, they went into a hold.  At that point, knowing that both it was going to push the liftoff until well after 10:30 PM and that it was the one night/week when we just can't stay up to any time we might want, we shut down the computers and went to bed.  

Which meant Murphy's Law demands it would launch last night, and it did, lifting off at 11:25PM EDT.

"Successful Failure" is an odd turn of phrase that I'm borrowing from Eric Berger at Ars Technica.  By the things that count the most, the mission was a failure.  Terran-1 failed to reach orbit, after the second stage failed to ignite properly and stay lit.  Furthermore, their chance of being the first rocket burning methane/oxygen to achieve orbit is pretty much over, barring some strange events happening to all the other engines and platforms.  

Berger argues that the mission was successful, proving out the most important aspects of the mission.  The first stage did a complete burn, going through Max Q (highest aerodynamic pressures on the vehicle) at about 80 seconds into the ascent and burning for over two minutes.  The 3D-printed booster stage seemed to perform completely nominally as did its nine 3D-printed engines.  That has to be a great relief to all involved.  

After all that and stage separation, something went wrong. It appeared the second-stage engine attempted to ignite but could not sustain this ignition. So far the company has not stated precisely what went wrong and we can only hope they got crap loads of data, enough to diagnose what happened.  Scott Manley has some video of the failure, and some of his analysis, but no major revelations.

Eric Berger writes:

It is proper to characterize Wednesday's launch as a success. Of the new era of commercially developed small launch vehicles, the Terran 1 rocket made it further on its debut flight than Astra, Virgin Orbit, Firefly, and ABL Space Systems. Only Rocket Lab, with the debut of its smaller Electron rocket in 2017, had a more successful initial flight. In producing a rocket with about 85 percent additively manufactured material, Relativity has flown with a substantially new manufacturing process.

The extent to which Wednesday's launch validated the additively manufactured structure of the Terran 1 rocket will need to be assessed with data from the flight—was it a close call, or was the structure genuinely robust? This information will likely help determine how much of Terran R is produced through 3D-printed technology.

Back in October '22, I had posted that CEO Tim Ellis was very aware that no privately funded company has achieved orbit on their first attempt but thought the mission might be graded on a curve.  That is, if they don't make orbit, customers pretty much get to decide if it was "close enough."  As he put it:

"While the rocket-loving engineer in me wants to say it's really orbit or nothing for the first flight, I think the business leader part of me knows that customers are going to tell us what enough looks like for the first flight."

Without hard data on what happened to the second stage anything here is guessing.  I mean, Virgin Orbit's mission had the same basic failure - second stage didn't work right - and that was a bad fuel filter in a system that has made orbit a few times.  The ESA's Vega C launch in December failed because of its upper stage on its second orbital mission.  It's not unprecedented for a rocket that has flown before to have that sort of failure.  

The big questions are whether or not the customers give the rocket a passing grade and if Relativity Space does another Terran-1 mission or goes directly to the bigger Terran-R.  We'll have to wait to find that out.

Terran-1 lights up the sky last night from Cape Canaveral, its methalox engines creating an unusual blue color in the flames. Relativity Space photo.


  1. That was a pretty, blue flame from those engines. I watched a rerun of the launch at another site. Yes, the second stage sputtered a few times and then quit.

    I will agree that it was a partial success for a new manufacturing process and methalox. I remember reading a sci-fi story where nanobots additively built spacecraft; is that next?

  2. Quite a few years ago when I was a baby engineer, we did a test on a valve pack installing in the place of the conventional nozzle on a legacy rocket motor. Think tail-steer. The test was ugly - one of the valves stuck and quickly exceeded the rated “open time” of its insulation. That high pressure stream of extremely hot gases and particles did what it does and turned the whole assembly into melty Swiss cheese. A few weeks later, we had a telecom with the manufacturer to discuss path forward and he was bubbly - this was a great test, they got lots of data, they knew how to fix the problem, they were already working on an updated design and wanted to schedule another test.

    About half way through all that, our lead engineer punched mute on the phone and said, “Are we talking about the same test?! This dude missed his calling - he should be in marketing.”