From Saving Money to Reaching New Levels of Speed
The evolution of manned and unmanned vehicles have gone a long way from the space race. Things that may have cost millions to produce now only cost a quarter of that. The evolution has gone far. Keep reading to find out more!
Evolution of the Space Shuttle
"Current Designs"
Rocket Boosters After STS-5 (November 1982), the casing was made .002 to .004 inch thinner, reducing the weight of each booster by 4,000 pounds.
After STS-7 (June 1983), engineers narrowed the booster’s throat and enlarged its nozzle. The changes increased thrust, enabling the shuttle to carry 3,000 more pounds of payload. During the days leading up to the launch of Challenger on STS-51-L (January 1986), freezing temperatures weakened an O-ring seal in a joint between two segments of the right booster. The weakness allowed hot gases to burn through the casing, causing the shuttle to break apart on ascent, which killed the seven-member crew. Two joints were redesigned with interlocking walls that had new bolts, pins, sensors, seals, and a third O-ring. |
In December 1994, parachutes (three per booster) were enlarged from 115 feet in diameter to 136 feet, slowing the jettisoned boosters’ descent, which reduced their damage at impact in the Atlantic Ocean. And to minimize damage during deployment, the chutes were packed in a circular, rather than zig-zag, pattern.
Propellant grain was modified after 2003 to avoid cracks in the fuel when the boosters are stored horizontally at temperatures below 40 degrees Fahrenheit. |
Engines The new oxidizer pump first flew on STS-70 (July 1995), while the new hydrogen fuel pump debuted on STS-104 (July 2001). Starting with STS-117 (June 2007), new onboard computers and sensors began providing better real-time monitoring of vibration loads in the turbopumps. High-precision casting during manufacturing has reduced the number of welds, cutting the number of engine inspections needed between flights.
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Space Shuttle Main Engines
In 1995, the power head was narrowed from a three-duct injector design to a two-duct one, and in 1998 the combustion chamber’s throat was enlarged. The changes reduced internal engine pressures and increased safety margins.To reduce friction from the oxidizer pump’s 23,000 revolutions per minute and the hydrogen fuel pump’s 34,800 rpm, silicon-nitride bearings were added to the two high-pressure turbo-pumps in 1995. In the oxidizer pump, the number of rotating elements was reduced from 50 to 28, while the number of bearings dropped from four to three. In the fuel pump, the rotating elements went from 30 to 14, and the bearings from five to two. |
Evolution of Orbiters
After January 2003, the wing leading edges were fitted with 66 tiny sensors, each of which makes 20,000 readings per second to detect impacts. To protect against impacts, NASA hardened the tiles on wing leading edges and added reinforced carbon-carbon blankets under the nose.
The shuttle has deployed six Tracking and Data Relay Satellites, beginning with STS-6 (April 1983). The satellites, along with three more sent up on Atlas IIA rockets, provide near-continuous communication during missions. Before TDRS, astronauts could talk to mission control only about 15 percent of the time while in orbit. A glass cockpit, with 11 flat panel color displays, replaced 32 dials and gauges starting with STS-101 (May 2000). |
Starting with STS-49 (May 1992), orbiters used a drag chute on landing, which relieves wear on the brakes and reduces rollout distance by up to 2,000 feet.
On the first four missions (1981-82), which each had only two astronauts, the shuttle had modified SR-71 Blackbird ejection seats. On STS-5, with a crew of four, the seats were disabled, and after STS-9 (November-December 1983), they were removed. Starting with return-to-flight STS-26 (September 1988), a telescoping slide-pole was installed to enable crew escape through the side hatch when the orbiter was below 30,000 feet and in a glide no faster than 230 mph. The original airlock was 150 cubic feet and located inside the mid-deck, with one hatch opening into the mid-deck and the other into the payload bay. Beginning in 1995, crew seats were made with aluminum alloys, which cut their weight from 110 pounds to 49. In the early 1990s, the airlock was enlarged to 185 cubic feet and moved into the payload bay, with a third hatch at the top for docking with the Russian space station Mir (1995-98) and the International Space Station (starting with STS-88, December 1998). |
Proposed Designs
NASA is ready to move forward with the development of the Space Launch System - an advanced heavy-lift launch vehicle that will provide an entirely new national capability for human exploration beyond Earth's orbit. The Space Launch System will give the nation a safe, affordable and sustainable means of reaching beyond our current limits and opening up new discoveries from the unique vantage point of space.
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The Space Launch System, or SLS, will be designed to carry the Orion Multi-Purpose Crew Vehicle, as well as important cargo, equipment and science experiments to Earth's orbit and destinations beyond. Additionally, the SLS will serve as a back up for commercial and international partner transportation services to the International Space Station.
"This launch system will create good-paying American jobs, ensure continued U.S. leadership in space, and inspire millions around the world," NASA Administrator Charles Bolden said. "President Obama challenged us to be bold and dream big, and that's exactly what we are doing at NASA. While I was proud to fly on the space shuttle, tomorrow's explorers will now dream of one day walking on Mars." |
This specific architecture was selected, largely because it utilizes an evolvable development approach, which allows NASA to address high-cost development activities early on in the program and take advantage of higher buying power before inflation erodes the available funding of a fixed budget. This architecture also enables NASA to leverage existing capabilities and lower development costs by using liquid hydrogen and liquid oxygen for both the core and upper stages. Additionally, this architecture provides a modular launch vehicle that can be configured for specific mission needs using a variation of common elements. NASA may not need to lift 130 metric tons for each mission and the flexibility of this modular architecture allows the agency to use different core stage, upper stage, and first-stage booster combinations to achieve the most efficient launch vehicle for the desired mission.