Wednesday, November 29, 2023

Firefly Runs First Test of Antares Replacement Engine

I've mentioned a few times around here (like here) that Northrop Grumman's booster, called Antares, has gone obsolete and will be unable to fly anymore.  This is the rocket that carried their Cygnus cargo vessel to the ISS.  The booster went obsolete because it relied on Russian engines just like the Atlas V.  The solution is that they're going to replace the Antares with a new launch vehicle called the Antares 330, which is being developed by Firefly Aerospace. 

Yesterday, we learned that Firefly had done the first test firing of the new engine that's going to be the power behind Antares 330, the Miranda.  The Miranda is also going to power Firefly's own Medium Lift Vehicle, or MLV.  

Firefly announced Nov. 28 that it conducted the test of its Miranda engine at the company’s Texas test site. A company spokesperson said the test, performed at 65% power, was designed to validate the engine’s startup sequence.

The company plans to work its way up to a full-duration test in the coming months, running the engine for 206 seconds. Miranda uses liquid oxygen and kerosene propellants, generating 230,000 pounds-force of thrust.

Firefly Aerospace's Miranda rocket engine hot fire test (Credit Firefly Aerospace) 

You probably know the kerosene propellant by the more common name of RP-1 (Rocket Propellant 1).  The combination of LOX and RP-1 is what powers the Merlin-1 engines of the Falcon 9.  In both vehicles, the engine is ignited by TEA and TEB (triethylaluminium-triethylborane) which produces the quick green flash captured in the photo above. I've seen occasional glimpses of that green flash at ignition of Falcon 9 launches.

The MLV (and Antares 330) will utilize 7 Miranda engines on the first stage and will be capable of producing 1.6 million pounds of thrust and the ability to deliver up to 10,000 kg of payload to the International Space Station on the Antares 330.

The MLV will be capable of sending up to 16,000 kg low Earth orbit as it will utilize the Miranda vacuum engine whereas the Antares 330 will use a Castor 30XL solid-fueled rocket motor for its first launches before an eventual transition to the Miranda vacuum engine.

In an interview earlier this month, Bill Weber, CEO of Firefly, said the schedule for the first MLV launch was driven by having the vehicle eligible for the National Security Space Launch (NSSL) Phase Three program in time to on-ramp to that program’s “lane one” for emerging launch vehicles. “We want to fly that mission in late ’25 so that we put ourselves in a position to qualify for the ’26 manifests in lane one,” he said. “So far, so good. We’re on track.” 

Weber went on to say:

“The incredible progress on our Miranda engines – designed, built, and tested in-house in just over a year – is another example of Firefly setting a new standard in the industry, building on the legacy of Firefly’s rapidly developed Reaver and Lightning engines, Miranda is the fastest propulsion system we’ve built and tested to date. This achievement reflects our rapid, iterative culture and our vertically integrated approach that allows us to quickly scale up the flight-proven engine architecture from our small launch vehicle, Alpha, to our Medium Launch Vehicle.”


  1. I kinda wonder if anybody has contacted SpaceX about purchasing their Keralox engines used in Falcon. After all, the Merlin engine is super-reliable and has a good track record.

    Likewise, for Raptor engines...

    Anyway, GO FIREFLY!!

  2. It is interesting to see non-legacy aerospace advance aerospace technology.

    My, how things are getting fun now!

    Will be interesting to see how the Mirandas work in actual use.