To get a sense of what it would be like to fly the Dream Chaser space plane hop into the front seat of a car – ideally a large SUV (Sports Utility Vehicle) or minivan – preferably with six friends. Instead of a steering wheel in front of you, picture a joystick. Instead of a dashboard, a row of flatscreen displays. Now shut and lock the doors, fasten your seatbelts and we’re ready to go. Next stop, the International Space Station (ISS).
Dream Chaser is being built by the Sierra Nevada Corporation (SNC) in the US mid-western state of Colorado. It is one of three concepts backed by Nasa to replace the retired Space Shuttle and is designed to carry crew and cargo to and from orbit. The other two concepts – SpaceX’s Dragon and Boeing’s, uninspiringly named CST-100 – are both capsules, not much different in appearance to the Apollo spacecraft that took men to the Moon.
But even Dream Chaser’s designers liken the space plane to a large family car, and sitting at the controls it’s easy to see why. The mock-up cabin is certainly no wider and the windows surrounding the two pilots offer similar visibility. Behind the front seats, there’s room for five more astronauts with a small area at the back for luggage. On the outside, it resembles a shoe with two wings poking out diagonally at the back.
The space plane’s squat, compact shape was inspired by a fuzzy 1970s spy photograph of an experimental Soviet aircraft. Nasa engineers spent more than a decade reverse engineering and developing the concept. They even built a full-sized mock-up before the project was quietly shelved. SNC has now been working on Dream Chaser for the last nine years and, with a recent extra $212 million from NASA, is getting close to finally turning the dream into reality.
“It started as a dream,” admits Mark Sirangelo, head of SNC Space Systems. “It was a very small group of people that looked to the future and said we think that when the Shuttle retires, that there’s a place for a modern version of that shuttle.”
“The reality is quite real now. We have built our vehicle, we have actually conducted our first test flight, the vehicle will do its first autonomous [atmospheric] flight later this year…and we’re now in the final three companies who are going to be looked towards to produce a vehicle that can take people and cargo back and forth to the space station.”
Comparisons with a mid-sized family hatchback even extend to the factory, on the outskirts of Denver, where the first space plane is taking shape. It resembles a garage workshop, where you expect to see mechanics tinkering with cars; instead they’re preparing the first Dream Chaser for flight.
The plane sits in a bay at the end of the room beneath a vast Stars and Stripes flag. Constructed primarily of carbon fibre, the first impression of Dream Chaser is that it’s, well…small. With no massive engines or cargo bay, and only a couple of metres off the ground, it is quite unlike any other space plane design. And whereas the Space Shuttle was, notoriously, the most complicated machine ever built, Dream Chaser is much simpler.
“We look at it what jobs are needed,” says Sirangelo. “We’re not taking big pieces to and from the Space Station any more, we’re taking people and critical cargo back and forth and it’s designed in size for that purpose.”
Dream Chaser will be launched on the top of an Atlas 5 rocket (although it could be launched on Europe’s Ariane rocket), with the astronauts lying on their backs looking through the front windows at the sky. Although not yet rated for manned spaceflight, Atlas 5 is one of the most reliable US launchers ever built. The space plane’s engines would only be fired in space to change orbit, catch up and dock with the ISS and de-orbit before returning to Earth.
Similar SNC engines have already flown in space on the first privately operated human spacecraft, Spaceship One, and are being built for Virgin Galactic’s Spaceship Two. Like the Shuttle, and these other designs, Dream Chaser would glide back to Earth – a feature its designers are keen to highlight.
“Within eight to 10 hours of leaving the station, we’re on the ground on a runway,” says Sirangelo. “We come home with less than 2Gs – twice the force of gravity – unlike most capsules, which come down to an ocean landing or a desert landing and come down at a much higher rate of descent. That could damage the experiments and could make it much more difficult for the people coming home.”
The ability to return fragile equipment or experiments from the space station is one of the big selling points of the Dream Chaser concept. The only return option at the moment is a cramped and bumpy landing in a Russian Soyuz capsule, which barely accommodates its three astronauts. There’s certainly room for cargo in the Dream Chaser (depending on how many astronauts are being flown) but where space planes really have the edge over capsules is their versatility.
The Shuttle was so much more than a space cargo hauler. It allowed, for example, astronauts to fix satellites and telescopes in orbit. Without it, the Hubble Space Telescope would still have blurry vision (and would probably have failed by now). But with the demise of the Shuttle, that ability was lost.
Now, Dream Chaser could bring it back. Like the Shuttle (and unlike most capsules)it has an airlock enabling astronauts to leave the plane for space walks. “The missions … could be to go out and repair things in space [or] help with the large and growing problem of space debris – how could we move a satellite out of the way before it causes a problem?,” says Sirangelo.
As a transport craft to and from the ISS, Dream Chaser faces stiff competition from SpaceX and Boeing. But Sirangelo believes, once the considerable development and construction work is done, it will find lots of different roles….just like any good family car.
“As with most SUVs, you haul your family around,” he says. “But sometimes you take supplies around, sometimes you go camping, sometimes you fix things with it and that’s what we’re trying to do with this vehicle.”