AmericaSpace
For a nation that explores
April 15th, 2012
Next Generation Spacecraft No Comparison To Shuttle
By Jason Rhian
None of the various spacecraft currently being developed to return U.S. astronauts to orbit have all the capabilities and capacities that NASA's decommissioned orbiters had. Photo Credit: Alan Walters / awaltersphoto.com
The crop of space capsules that are currently being developed to return U.S. astronauts to orbit have all-too-often been dubbed "replacements" for the winged spacecraft that ferried crews to orbit for the past thirty years. But how similar is the shuttle to any of these new spacecraft? With few exceptions – there are virtually no similarities. Under the Obama White House and his appointed officials, NASA has been directed to encourage the commercial space industry to produce spacecraft and launch vehicles to carry cargo and crew to low-Earth-orbit (LEO). It is hoped this will free up the space agency to focus on sending astronauts beyond LEO. The spacecraft that have emerged in CGI imagery, PowerPoint presentations and occasionally real life all vary in their appearance and capabilities.
To highlight the differences between the shuttles, now on their way to museums and tourist attractions across the nation, and these emerging spacecraft – specific elements of each are detailed below.
Although NASA's next spacecraft, Orion, and the commercial spacecraft that are currently being developed are touted as being "replacements" for the shuttle – none of them compare to the robust suite of capabilities that the space shuttle had. Photo Credit: Jason Rhian
The Shuttles – Discovery, Atlantis and Endeavour. Each of these winged spacecraft has a payload bay some 60 feet in length – which is designed to carry a wide range of payloads in a variety of different configurations. The shuttles also have a remote manipulator system (RMS – the shuttle's robotic arm) which allows for both cargo and crew to be moved around in the vacuum of space. An airlock that allows crew members to perform extra-vehicular activities.
Length – 122 Feet
Width – 78 Feet
Payload Bay – 60 Feet long by 15 Feet wide.
Remote Manipulator System
Reusable
The Orion spacecraft, built by Lockheed-Martin, has been often dubbed as the shuttle's replacement – but how many of the shuttle's capabilities are incorporated into the capsule-shaped spacecraft? It turns out, very few. Image Credit: NASA
Lockheed-Martin's Orion spacecraft. This vehicle is not a part of NASA's new commercial efforts per-se; however it is commonly referred to as the orbiter's successor. There are virtually no similarities between NASA's fleet of decommissioned orbiters and this new spacecraft. Orion is capable of being re-used six times at most. Orion has no payload bay, no robot arm and if crews wish to conduct EVAs – the capsule will have to be depressurized, requiring the entire crew (Orion has the capacity of carrying up to six astronauts) to don their space suits. In fact, if the service module section of the spacecraft was two feet less in diameter – it could fit inside of the shuttle's payload bay. When Constellation was NASA's program-of-record, there was an effort by Canada (the developers of many of the robotic arms NASA uses) to build a robot arm to be used on Orion.
Length – 26 Feet
Diameter – 16.5 Feet
Payload Bay – NA
Remote Manipulator System – None
Partially Reusable
Boeing's CST-100 has been called a "space-taxi" and can either ferry astronauts or cargo (or some combination of the two). Image Credit: The Boeing Company
The Boeing Company's CST-100 Space Taxi. This spacecraft is in some ways a simpler version of the Orion spacecraft. It can carry a crew of six, cargo (the amount of cargo would vary depending on the number of astronauts on board. That is about all this vehicle is capable of. It is designed to ferry humans and materials to orbit – and back, it is not reusable and has no EVA capabilities. Although the exact size of the spacecraft is unavailable it is estimated to be larger than the Apollo spacecraft but smaller than Orion.
Length – Unknown
Width – Unknown
Remote Manipulator System – None
Partially Reusable
Of all the capsule-based systems that are under development, SpaceX's Dragon spacecraft is the most-similar to the space shuttle. However, the differences in scale, are dramatic. Image Credit: SpaceX / NASA
SpaceX's Dragon spacecraft. In terms of basic abilities by the capsule-based systems – Dragon actually comes the closest to the shuttle in terms of capabilities. It is in terms of scale that the chasm of differences - appear. The dimensions of the payload segments work out to provide approximately 350 cubic feet of pressurized payload capacity. In terms of the spacecraft's unpressurized elements, Dragon has about 4 cubic feet of recoverable and 490 cubic feet of non- recoverable payload capabilities. The Dragon is designed to carry up to seven astronauts.
Height – 9.5 Feet
Diameter – 11.5 Feet
Payload Capacity – Pressurized – 350 cubic feet – Unpressurized – 490 cubic feet
Remote Manipulator System – None
Reusable
In a break from what many commercial companies are producing (capsule-based spacecraft) – Sierra Nevada Corporation has opted for a space plane design. Like NASA's decommissioned orbiters, this space plane is reusable. Unlike NASA's retired fleet of shuttles however, the thermal protection system is ablative and will need to be replaced after ten flights. Image Credit: SNC
Sierra Nevada Corporation's Dream Chaser spacecraft. Physically the most similar of the space taxis to NASA's space shuttle, the Dream Chaser space plane is reusable and is based off of one of test articles that was used to design the space capacity is. Unlike the shuttle, Dream Chaser will utilize an ablative thermal protection system that would require replacement after several flights. The Dream Chaser is not quite 30 feet in length compared the space shuttle's 122 feet.
Length – 29.5 Feet
Width – 22.90 Feet
Remote Manipulator System – NA
Reusable
The one spacecraft that comes closest to emulating the space shuttle, Dream Chaser, is not even a quarter the length of NASA's retired fleet of orbiters. It has no robotic arm and lacks the EVA capabilities present on the space shuttle. Given that most of these vehicles could actually fit into the orbiter's payload bays – the capacity to launch huge payloads such as the Hubble Space Telescope and whole segments of the International Space Station – has been lost. It is unknown how long these multiple capabilities the U.S. will have to do without.
Space shuttle Discovery will be retired to the Smithsonian's Steven F. Udvar-Hazy Center in Washington. Atlantis will take a short road trip to the Kennedy Space Center Visitor Complex in Florida and Endeavour will be sent to the California Science Center located in Los Angeles, California. The shuttle test article, Enterprise, will be moved to the Intrepid Sea, Air and Space Museum located in New York (Discovery will take Enterprise's place in the Smithsonian).
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