Profound Propellant Problems Prompt DARPA to Cancel ALASA

Alas..No ALASA Credit: DARPA

Alas..No ALASA
Credit: DARPA

The growing list of potential smallsat launchers thinned out a bit last week with the news that DARPA, the Defense Advanced Research Projects Agency, has cancelled ALASA, the Airborne Launch Assist Space Access program which was awarded to Boeing in 2014. The story, reported in Space News, cites difficulties in maintaining safe control over the high performance, but even higher risk NA-7 propellant intended to power the 45 kg payload capacity booster as the reason.

According to the report, two ground tests of the nitrous oxide /acetylene propellant combination, which would have been pre-mixed before launch in a bid to simplify the vehicle’s plumbing, resulted in explosions.

Had the program, the overall goals of which were to achieve 24 hour launch capacity for under $1 million per flight proceeded as planned, it would have seen as many as 12 test flights beginning in early 2016. Given that the operational plan called for a piloted F-15E to carry the rocket to a launch altitude of 12,000 meters, the propellant instability proved problematical.

ALASA follows two previous small launcher projects by DARPA into the history column without producing flight hardware, but comes at a time when the broader commercial market is offering solutions similar to those contained in the objectives, albeit at a higher price point. Atlanta based Generation Orbit is developing GOLauncher 2, a small, two stage, air launched rocket which will be carried aloft by a Learjet 35. In 2013 NASA’s Launch Services Program awarded to Generation Orbit and GOLauncher 2 a contract for the launch of three 3U cubesats to take place in August 2016 from Cecil Field Spaceport in Jacksonville, Fla. At 100 lbs to LEO and launch to any inclination, its capacity is nearly identical to that of ALASA, suggesting that if DARPA wants to take a more conventional route they know who to call.

One issue with the sort of high risk/high reward programs of the type that DARPA is commissioned to undertake, is that they often incorporate multiple advancements at the same time, and if a given program is cancelled over difficulties with one element, it may prevent other elements from being tested as well. In this case, ALASA’s rocket featured an unusual configuration in which the same set of rocket engines powered both the first and second stages by virtue of being mounted to the second, with the first stage essentially being a propellant drop tank. As a somewhat unique solution to reducing the vehicle’s mass, it would be interesting to see developed.

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4 Comments on "Profound Propellant Problems Prompt DARPA to Cancel ALASA"

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  1. Zed_WEASEL says:

    There are 2 separate engines on the ALASA rocket. It was shown in a presentation animation on you tube.

    Guess the USAF need to convert a few F-15 jets into unmanned drones to test the ALASA rocket.

    • Stewart Money says:

      Good observation regarding engines. Would have been a three stage rocket.

  2. Robert Clark says:

    Surprised they tried to use acetylene. It is notoriously unstable. But in fact it can be done using currently existing rocket stages:

    Dave Masten’s DARPA Spaceplane, page 2: an Air Launched System.

    Bob Clark

  3. Tom Billings says:

    It is notable who was supplying the propellant, as far as was stated in the article. The 11 years of work with Nitrous Oxide Fuel Blend propellants by FireStar Technologies was nowhere mentioned. Nor was their patent on many mixtures that included as fuels ethane, ethylene, and acetylene. IIRC, in that patent, acetylene was *never* used without one of the other two being present in large percentage. Yet, Boeing chose their NA-7 propellant, with a pure acetylene mixture, which, of course could not be coered by the patent.

    This clear avoidance of FireStar Technologies and the end run around the patent may be the biggest reason for the failures in the propellant program for ALASA. It follows a unexplained sequence in 2012, where the ISS safety review board approved a test of a 100lb. thruster using one of FireStar’s propellant series, covered under their patent. Then, with no announcement I could find, the experiment was removed from the flight manifest just a few months before flight.

    Was Boeing, or Aerojet/Rocketdyne exerting influence in one or both cases?

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