Small Space News Story Roundup 80

Because, well, you know. It's not that there isn't any news, it's just not much to talk about.

Another company tests a Rotating Detonation Engine

We've talked about RDEs for a while now. My first post on the subject appears to have been in May of 2020, so almost six years to the day. At the time, I wrote that it wasn't a new idea:

Rotating detonation engines, or RDEs, sound like something out of science fiction, but the concept is about as old as the space age itself. In the late 1950s and early '60s, aerospace engineers working on rocket engines envisioned RDEs as a way to turn a problem into a solution. “Sometimes the rocket motors would get a real bad instability and you’d get an explosion,” pioneer Arthur Nicholls recalled in a University of Michigan interview shortly before his death. “Then it led to the idea—well, what if we use that?” 

Like many things observed that early in space exploration, the physics of what was going on wasn't well understood, but there has been a lot of time for that physics to develop. The main advantage of the RDE is reduced weight of the engine.  In conventional liquid rocket engines, the fuel and oxidizer are pressurized and fed into the ignition chamber using bulky turbopumps and other complicated machinery.  An RDE doesn’t need these pressurization systems, because the shock wave from the detonation provides the pressure. In this week's Rocket Report from Ars Technica, Eric Berger writes about tests from Astrobotic.

Astrobotic on Thursday announced the successful hot fire testing of its Chakram rotating detonation rocket engine (RDRE) at NASA’s Marshall Space Flight Center. Two Chakram engine prototypes completed eight successful hot-fire tests, accumulating more than 470 seconds of total run time without any discernible damage to the engine hardware, the company said.  The campaign included a 300-second continuous burn, which is believed to have set the record for the longest duration hot firing of an RDRE engine to date.

The engines seem too small to me, they produced 4000 pounds of thrust, but I may well be thinking of completely different uses than Astrobotic is aiming for. Berger mentions two engines being used in a vehicle, but that's still around 8000 pounds, certainly under 10,000, which is barely enough to get most of us off the sofa on Thanksgiving. 

Astrobotic's Chakram rotating detonation rocket engine during tests this week. Credit: Astrobotic

With both ULA's Vulcan and Blue Origin's New Glenn grounded, getting to orbit just got harder

I still haven't seen anything with details about what went wrong with New Glenn's second stage last week, but the internet has been buzzing about it being that the BE-3 upper stage engines malfunctioned - presumably one of the two and not both of them. Blue's customer's payload has already re-entered and burned up. 

While Vulcan's solid rocket (first stage) boosters lost a nozzle on one of the two engines on each of their two missions, the vehicles' control systems increased their output enough so that it could still deliver their payloads to orbit. Northrop Grumman said Tuesday it had taken a $71 million charge due to an anomaly with the solid rocket booster that grounded the Vulcan Centaur rocket.

So how do big payloads get to those orbits? Obviously, SpaceX is still flying but they don't have infinite capacity. The ability to put those payloads into tough orbits has really been clamped. 

Still, it's not a total shutdown. There's this:

No solids, no problem … The Space Force could launch certain missions without solid rocket boosters that carry lower mass or are bound for lower orbits. For example, the service could launch an upcoming Space Development Agency mission on Vulcan, Lt. Gen. Philip Garrant, Space Systems Command chief, told reporters in a separate briefing. “Essentially, if it doesn’t rely on a solid, there’s no reason why we can’t launch, and I’m committed to supporting that and keeping that mission going,” he said. The Space Force has switched four GPS III missions from a Vulcan rocket to a SpaceX Falcon 9 vehicle since December 2024.