New Mexico-based ARCA Space Corporation has announced that it is developing the world's first Single Stage to Orbit (SSTO) launch vehicle that can deliver both a small payload and itself into low Earth orbit, at a cost of about US$1 million per launch. Dubbed the Haas 2CA after the 16th century rocket pioneer Conrad Haas, the new booster uses a linear aerospike engine instead of conventional bell-shaped rocket engines to do away with multiple stages.

Getting into space is a very complicated affair. To put a payload, like a satellite, into orbit means shooting it out of the atmosphere at about 18,000 mph (29,000 km/h). This takes significant energy in the form of rocket propellant, which must be held inside a rocket and burned by the rocket engine. Unfortunately, that means adding more fuel to lift the rocket, its engine and the original fuel, then more fuel to lift all that, then more fuel to lift that fuel.

This is one of the reasons space agencies and private companies use staged rockets. By using a large first stage to lift smaller upper stages in sequence and then discarding them along the way, a payload can be sent into orbit without having to lift the bulk of the entire launch vehicle as well.

Another reason is that conventional rocket engines can only work efficiently inside a rigidly defined set of altitudes because the thrust of the rocket must work against the air as it shoots out. This is a major reason why SpaceX's Falcon 9, for example, uses two stages instead of one. The engines in the first stage are optimized to work best at sea level and low altitude, while the second stage engine is designed for the rarefied atmosphere on the edge of space.

What ACRA is trying with the Haas 2CA is to replace the conventional engines with a linear aerospike engine, which the company claims is 30 percent more efficient than those used today. It's an idea that dates back to the 1960s and basically works by cutting a rocket engine's bell in half, then placing the two halves back to back to form a tapering spike.

The principle behind the aerospike is that the air itself acts as the missing half of the rocket bell, containing the hot gases as they leave the combustion chamber. This means that as the rocket flies higher, the thinner air holds the gases less tightly and they spread out more as if the rocket bell has gradually grown larger. This allows the aerospike to automatically adjust itself in flight, turning itself from a sea-level engine into a high-altitude one.

According to ARCA, this allows the Haas 2CA to generate a higher specific impulse compared to similar engines. A specific impulse is a measurement of how much a rocket can change the momentum of a unit of mass for a unit of fuel or, in English, how big a total push rocket can give for a tank of fuel. In addition, by using 16 combustion chambers that can be individually throttled, the rocket can be steered without the need for a heavy and complex gimbaling system.

When completed, the Haas 2CA will stand 53 ft (16 m) tall with a diameter of 4.95 ft (1.5 m) and weigh 1,210 lb (550 kg) or 35,887 lb (16,290 kg) fuelled, thanks to ARCA's proprietary composite materials for the propellant tanks and other components. Unlike other systems that use cryogenic propellants, the Haas 2CA burns hydrogen peroxide and RP-1 – a highly refined form of kerosene – punching 50,500 lb of thrust at sea level. This will allow it to place a payload of 220 lb (100 kg) into low Earth orbit at 24 hours notice for about $10,000 per kilogram or $4,545 per pound.

Aimed at the microsatellite market, the Hass 2CA is being developed along with NASA's Kennedy, Ames, Wallops, Marshall, Stennis, and Johnson Space Centers for the Cooperative Opportunity Program, and is scheduled to make its maiden flight from the Wallops Flight Facility in 2018. In addition, the company is negotiating to use the Spaceport America in New Mexico as a launch base.

"When the Haas 2CA rocket launches, it will be the first rocket in history to place itself entirely into orbit," says Dumitru Popescu, ARCA Space Corporation CEO. "This opens new frontiers for exploration of the Solar System as the rocket can be refueled in-orbit and re-utilize its aerospike engine thus eliminating the need for additional upper stages. After the full qualification, the vehicle could be operated from inland spaceports as there are no stages that fall on the ground at burnout. Staged rockets, even though they provide more payload performance for the same takeoff mass, are less reliable because of an increased number of parts due to flight events requested by staging and ignition of the upper stage engine.

Also, staged rockets are deemed to be more expensive because they are literally made up of more than one rocket. Manufacturing and assembling more rockets in one launcher requires more, time, money, and personnel. The SSTO technology, once implemented, will increase the space flight responsiveness and lower the cost to values expected by the industry for decades. This rocket will also be the fastest vehicle to reach orbit, taking less than five minutes."

The video below introduces the Haas 2CA.

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