European solid rocket passes key test

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WASHINGTON — A solid rocket booster designed for both the Ariane 6 and Vega C next-generation launchers completed a successful test firing Monday, clearing a hurdle for the maiden flights of both vehicles.

Organizations working on the P120C solid rocket held the 135-second test fire at the European spaceport in Kourou, French Guiana, demonstrating the requisite burn time for the first stage of flight for both vehicles.

Built by an ArianeGroup and Avio joint venture called Europropulsion, the P120C will serve as the first stage of the Avio-led Vega C light-lift launcher and as a strap-on booster for the heavier Ariane 6 rocket from ArianeGroup. Avio told SpaceNews by email that Vega C’s first launch is scheduled for around the end of 2019. Ariane 6’s maiden flight is slated for 2020.

The European Space Agency said the July 16 test occurred without incident and “met expectations” — good news since solid-fuel rockets cannot shut off once ignited. The agency plans several months of analysis with the test data.

Another two test firings of the P120C will take place to qualify the booster ahead of Vega C’s first flight, according to an ArianeGroup statement. ESA said the next firing will take place at the end of the year.

Weighing 150 metric tons (eight tons for the casing and 142 tons of propellant), the engine is the largest monolithic carbon-fiber solid rocket motor in the world, ArianeGroup and Avio say.

A compromise reached in May by European Space Agency members funding launch vehicle development will keep production of the P120C in Italy, allowing Avio to produce up to 35 boosters annually. A previous arrangement would have split production between Colleferro, Italy-based Avio and MT Aerospace of Augsburg, Germany.

The economies of scale provided by using the same booster for two rockets and concentrating production in one place are a key aspect of reducing the price for Ariane 6 missions by 40 to 50 percent compared to the Ariane 5 in use today.

The P120C solid rocket motor is almost 60 percent more massive than the P80 motor used on today’s Vega rocket, and will help increase Vega C’s lift ability to 2,200 kilograms of payload (from Vega’s 1,500 kilograms) to low Earth orbit.

Ariane 6 in its early days is expected to lift between 4,500 and 5,000 kilograms to geostationary transfer orbit when equipped with two solid rocket boosters (Ariane 62), and 11,500 kilograms with four solid rocket boosters (Ariane 64). Arianespace, which markets the Ariane 6 and Vega C rockets, says the Ariane 64 version has “significant growth potential” to lift heavier payloads over time.