Dream Chaser is one of three systems NASA is considering for U.S. human transportation to and from the international space station. Dream Chaser has been called a “mini shuttle,” and to the general public appears to be a small version of the original space shuttle. It is useful to review how the shuttle was used and what it did.
The space shuttle was the face of NASA to most of the world for 30 years before it was finally retired in 2011. Twenty or 50 or 100 years from today, the shuttle will be remembered as an extremely useful vehicle and a technical marvel. Nothing can compare to its functional abilities, serving as a launch vehicle, cargo carrier (both up and down), human transporter, on-orbit living quarters, construction shack, space station builder, satellite launcher and retriever, satellite servicer, and research lab in itself.
It was mostly reusable, entering the atmosphere like a spaceship, then transitioning to operation as an airplane and landing on a runway, with the crew walking away with dignity and relative comfort, and the entire final approach and landing viewable on live TV by millions around the world, reminding U.S. citizens of America’s technical and geopolitical leadership.
Of course, Dream Chaser cannot do all that the original shuttle did, but it can perform the shuttle’s single most important task of transporting crews to the ISS and returning them to a safe and dry landing on a runway in full view of the public.
The two other candidates for future U.S. human transportation to the ISS are both capsules resembling those from the Mercury, Gemini and Apollo programs of the 1960s. The proposed new capsules also resemble the Russian Soyuz capsule.
Developers of the capsules will be attempting to develop ground landing systems, with ocean landing as a contingency. They will need to develop both methods.
Mercury, Gemini and Apollo crews landing in capsules in the saltwater ocean were required to wait up to several hours until a rescue ship or helicopter arrived to pull them to safety. With all the unavoidable pitching and bobbing in the open ocean, more than half the waiting astronauts got seasick. A capsule makes a poor boat. We almost lost astronaut Gus Grissom in a Mercury program landing due primarily to difficult recovery operations in the open ocean.
Reliable ground landing of a capsule using propulsion will be difficult with poor downward crew visibility and limited maneuvering capability.
A capsule coming to Earth on parachutes will need to land in unpopulated and relatively flat areas of the United States. Since the parachutes have little or no maneuvering ability, it will be a challenge to reliably avoid hazards such as ravines, power lines, cabins, livestock and barns. This must be done under normally windy conditions.
Crews returning from orbit in a Russian Soyuz capsule, landing in remote areas of Russia, must wait sometimes hours until rescue people arrive. We have seen images on Russian TV of rescue personnel struggling to pull cosmonauts from a Soyuz capsule lying on its side. We then see rescue people placing them on stretchers for transport to recovery facilities.
Experience with capsules landing on water or land has shown either method to have been relatively crude and unfriendly to crews and other operations personnel.
Astronauts I have known would be willing to ride down on a parachute if that were the only way to get assigned to a mission, but astronauts (and pilots) also want to touch down on a runway, if at all possible.
Dream Chaser will perform better and have lower operating costs than either of the capsule systems, although those differences could be small compared with the advantage Dream Chaser would have in enabling live TV coverage of the entire approach and landing of each flight.
Dream Chaser could become the face of NASA to U.S. citizens and to the world for the next several decades.
Dr. O. Glenn Smith is a former manager of shuttle systems engineering at NASA’s Johnson Space Center, and is not affiliated with any aerospace company.
