Masten Space Systems, which builds reusable suborbital rockets, recently tested a vehicle that took off, flew to 50 meters altitude, flew 50 meters horizontally downrange, and then landed softly on another concrete landing pad. It did so using new software called the Guidance Embedded Navigator Integration Environment (GENIE), which was developed by the nonprofit Draper Laboratory in Cambridge, Massachusetts.
This is pretty cool, but…the DC-X did the same thing in 1995.
To be fair, the DC-X was controlled at the time, not flying completely autonomously. (Usually, that control was former astronaut Pete Conrad, if I remember correctly.) It did have automatic flying control systems, and in particular used the automatic landing mode several times. On its next to last flight, it flew to an altitude of over 3,000 meters.
Built by McDonnell-Douglas, the DC-X was a 1/3 scale demonstrator for a follow-on vehicle called the Delta Clipper, or DC-Y. The DC-Y was to be a manned, single-stage-to-orbit (SSTO) reusable spaceship. It was originally funded through the Strategic Defense Initiative. It flew eight test flights in 1993-1995 but the aeroshell was cracked upon landing on the last flight. The vehicle was sent back to MacDac in Huntington Beach for repair. It was fitted with a new lithium-aluminum LOX tank and a graphite-composite fuel tank that substantially decreased airframe weight. It was christened the DC-XA and flew four more flights from White Sands in 1996. On the fourth flight, on July 31, one of the retractable landing legs failed to extend on landing and the vehicle fell over. It suffered considerable damage, and it was decided there was not enough money left to fund repairs.
Turnaround time between the second and third flights in 1996 was 26 hours; the vehicle successfully validated a rotation of the vehicle prior to landing – the most difficult part of a tail-first soft landing – as well as a number of software and hardware innovations.
I’m not dissing the work of Masten with the Xombie. It was funded partially by NASA, and it is validating control systems and software that could be used on Earth, on the Moon, or even on Mars. It just bothers me that we could be flying reusable spaceships today that would be the third or fourth generation descendants of the DC-Y today. For a fictional look at how the world could have been if such vehicles were in common use, see the Firestar series of novels by Michael F. Flynn.
Early concept of the DC-Y
The SSTO vertical-takeoff-and-landing vehicle idea has been around since the 1950s; the Luna in the landmark film Destination Moon was such a vehicle, even if it did use a parachute for final landing back on Earth.
Luna, which took off and landed vertically, “as God and Robert Heinlein intended”
In the 1960s and 1970s a wide range of designs were promoted by such visionaries as Gary Hudson, Max Hunter (who designed the Mercury capsule) and Phillip Bono. Plug nozzles, drop tanks – all kinds of vehicles were designed. Some very large ships were designed to take off from a body of water!
Gary Hudson’s Phoenix C
Even using very light airframes utilizing “solid smoke” (a silica aerogel), composite fuel tanks and honeycomb aluminum structures, the numbers just never came out in favor of successfully flying a single-stage rocket directly from Earth into orbit and back again. Liquid hydrogen and LOX (liquid oxygen) as fuel and oxidizer are the rocket fuel combination that produces the most energy per pound, but liquid hydrogen isn’t dense enough – the fuel tank has to be so large that a significant amount of the performance of the fuel is lost due to increased airframe weight. Improved engines or even nuclear engines are probably required to make this concept work. That’s why most of the SSTO designs since that time have taken off and/or landed like aircraft. (For a detailed discussion of the DC-X and SSTO, see Halfway to Anywhere by G. Harry Stine.)
Xombie isn’t designed to fly into orbit; in fact, Masten seems to be focusing on suborbital rockets. I have to hope, though, that the knowledge gained through these tests will help to lead to a viable SSTO someday once the propulsion technology is available to make it possible. If nothing else, it might help SpaceX as it tries to build the Grasshopper reusable suborbital rocket and the fully-reusable version of the Dragon capsule and the Falcon 9 launch vehicle. I wouldn’t usually expect such a technology transfer from one company to another, but the GENIE software was written by a nonprofit lab. They may be persuaded to license it to multiple users.
SpaceX Falcon 9 – reusable version soft-lands vertically
Update, October 2013: Nobody called me on it, but Max Hunter, mentioned above, was not the designer of the Mercury capsule. That was Maxime Faget, who was a very interesting guy in his own right. That’s what I get for writing the piece pulling stuff out of my brain without fact-checking.
Also, the Falcon 9 version 1.1, which was first test-launched about a week ago, will have much cooler-looking landing legs than those shown above:
This is a clipping from the Falcon 9 page on the SpaceX site. It appears they hinge near the engines, and the landing feet or pads are located at the top. There are rumors that the next Falcon 9 launch may involve an attempt to soft-land the first stage. A restart of the center engine of the first stage was mostly successful in the first test flight. A restart of the second stage was more problematic, and it may delay the next test flight.