The Space Shuttle Era, Winding Down

On February 24, 2011, the space shuttle Discovery launched for its final trip into orbit. The main objective of the STS-133 mission is to deliver and install a permanent multipurpose module (what NASA is calling a ‘floating closet’) to give occupants of the International Space Station increased storage. Discovery is also delivering Robonaut 2 to the ISS. It is the first human analogue to go in space; it will undergo a series of tests to see how well a robot can function in a zero gravity environment. (Pictured is Discovery on the launch pad the eve before launch. February 23, 2011.)

While this is Discovery’s last fight, the shuttle program as a whole has two more mission lined up: STS-134 will see Endeavour launch into orbit on April 19, and STS-135 will see Atlantis launch on June 28. Even taking into account possible delays and scrubbed launches, it’s safe to say the shuttle program will likely be finished by the end of 2011. So, what’s next?

Designing follow up missions is an interesting problem. Past accomplishments and future goals have to coincide with the realities of budgetary restrictions to keep the organization progressing. In the case of the space shuttle program, it was a natural progression for NASA. First proposed in 1969 not long after the first successful lunar landing, the organization had to look ahead to its future in space, far beyond the excitement of a now-past major technological achievement.

In designing its next big program, NASA had to contend with not only the let down following the lunar landing, but also severe budget cuts. Consideration of designs for the space shuttle began in 1970, the year that saw the ill-fated Apollo 13 mission. The frightening cost of spaceflight, both monetary and in human life, was becoming increasingly obvious. There was pressure for NASA to develop a safer, cheaper vehicle. (The damaged Apollo 13 service module as seen from the command module Odyssey. 1970.)

Proposals ranged from a fully reusable manned booster and orbiter to dual strap-on solid propellant rocket motors and an expendable liquid propellant tank. In the end, the decision came down to economics. After two years of research and development, a reusable space shuttle using solid rocket boosters was determined to give NASA the most bang for its buck.

The space shuttle is, first and foremost, a transport vehicle (the mission designations of STS stands for space transportation system). It was designed as a low-Earth orbital vehicle with the capability to place satellites into orbit as well as enable astronauts to make orbital repairs. The shuttle would also benefit further manned space exploration. Manned spacecraft designed to land on the Moon or Mars as well as orbital research stations could be lifted into orbit by the shuttle and assembled by astronauts. Perhaps the most appealing aspect of the shuttle over its capsule-inspired predecessors is its reusability. Each shuttle orbiter was, according to initial specifications, designed to make at least 100 flights. (Left, Discovery launches on March 15, 2009.)

Beyond its capacity as a transport vehicle, the shuttle is a fascinating development in spacecraft. It is the first true aerospace vehicle: it launches on a rocket, manoeuvers in orbit like a spacecraft, and lands like an airplane. It is the same concept as the X-20 spaceplane that never was.

The X-20 – also known as DynaSoar for ‘dynamic soaring’ – was the proposed follow up program to the X-15 research program.

The X-15 proved that aircraft-inspired vehicles could safely return from space and land like an aircraft through a series of flight between 1958 and 1966; the aircraft was retired from active missions in 1970. Some would consider the X-15 to be the first spaceplane. It was launched from under the wing of a converted B-52 aircraft after which its powered ascent phase brought it to its apex. It arced over the top of its path experiencing a brief few minutes of weightlessness before reentering the atmosphere. It landed on a runway on the dry lakebed at Edwards Air Force Base.

The X-15 had limitations related to its small size. At only 50 feet long, it was too small to carry enough fuel to reach its peak altitude. Launching it from under the B-52’s wing enabled it to begin its powered flight at altitude, conserving fuel for the real push towards high altitude. The aircraft also didn’t carry enough fuel to reach orbit. A ballistic arc resulting in a few minutes of weightlessness was all it got. The X-20 (pictured as an artist’s concept to the left) was basically a larger X-15 that launched from a booster rocket, used the same ballistic reaction controls for orbit manoeuvres, and land like an aircraft.

The program never left the drawing board – Sputnik pushed all programs that couldn’t achieve immediate orbit far into the background. Capsules such as Mercury took precedence, providing a cheaper and faster means to spaceflight.

In the early 1970s, however, NASA was without the severe pressures that allowed the capsule-style spacecraft to dominate the lunar program. The time was right to revisit the lost spaceplane. But spaceflight needs a purpose. The space shuttle focused on bringing research and development in space sciences and astronomy to the forefront.

In 1981, NASA released a “News Reference” packet for the space shuttle, providing detailed technical information as well as prospective mission goals for the program. Evident throughout the document is the high hopes NASA had for the program.

Some of the biggest beneficiaries of the shuttle was to be unmanned satellites. One of the shuttle’s first charges was to carry into orbit the pieces that would assemble to make the European Space Agency-designed Spacelab, an orbital zero-gravity environment for all sorts of scientific research. The shuttle was also expected to put into orbit the “building blocks” for constructing large solar power stations. Such an undertaking could effectively convert the unlimited solar heat and sunlight of space into electricity for an increasingly energy-hungry world.

The future of manned spaceflight was also expected to experience a boom from the ease of access to space afforded by the space shuttle program. The vehicle was expected to carry into Earth orbit the modular units for self-sustaining orbital settlements. Astronauts could inhabit these settlements for long-duration stays. They could use their time to build and maintain solar power stations, work on the manufacturing of drugs, metals, electronics crystals, and glass for lenses. All this work would be easier in zero gravity; working in such an environment could reduce the cost of certain drugs, create new alloys, produce drugs and lenses of unusual purity, and enable crystals to grow very large.

Not only could the shuttle achieve these lofty goals, it could do so at an impressive rate. Multiple flight monitoring systems (control centres and round the clock staff) would support multiple simultaneous missions ensuring the optimal use of the shuttle. NASA’s initial proposal foresaw about 50 shuttle flights per year. At nearly a launch a week, this would be a new record. Previously, the Gemini program had progressed the fastest with 10 successful manned launches in only 20 months. (Above, the space shuttle Discovery in the dawn light prior to launch. August 2009.)

As originally presented on paper, the space shuttle was an impressive program almost too good to be true – significant payoff for a fraction of the Apollo-era cost. But perhaps the initial promises were too good to be true. Discovery’s recent launch for the STS-133 mission marks the 133rd mission in the space shuttle program. By the initial calculation of 50 launches per year, the shuttle program should be nearing it’s 1,400 or 1,500th mission by now.

The program got off to a slow start with only two launches in its first year and twenty-three launches in its first five. In 1986, NASA experienced a serious setback after the loss of the Challenger space shuttle in January. The subsequent investigation and the time spent addressing and correcting the problem set the program back; the next mission launched nearly three years later in September of 1988. Between 1988 and 2003, the shuttle program averaged about six launches per year. The loss of a second crew and the shuttle Columbia in 2003 again set the program back. Only 19 missions have flown since, following a two-year hiatus after the loss of Columbia.

The 130-plus shuttle missions have not delivered on the initial promises made. Repairs made to the Hubble telescope have certainly helped the satellite retain its central importance for astronomers. But what about the proposed cheaper drugs and more perfect glasses? The International Space Station (right in 2009), construction of which began in 1998, is still incomplete. No spacecraft destined for the Moon or Mars have been assembled in orbit.

The shuttle is a spectacular vehicle with great potential, but the program never had a truly concrete goal and certainly lacked the impetus to force a stunning technological achievement. Apollo is fascinating: Kennedy and the Cold War presented NASA with a lofty goal and told the organization to make it happen. Such an achievement in a completely new arena in a short time frame is simply spectacular.

The shuttle program came to be in the opposite situation. NASA had more knowledge to draw from and designed an impressive vehicle; brilliantly designed for multiple uses, has a significantly larger crew and cargo capacity than Apollo, lands like an airplane thus negating pesky and expensive splashdowns, and has a mere 14-day turn around time. What the shuttle has never had is a concrete goal. The capacity to lift and assemble impressive space stations and spacecraft is great, but if there’s no need for those stations or spacecraft, the shuttle won’t put them in orbit. And it hasn’t. (Pictured, Endeavour comes in for a landing on a runway. 2009.)

So what comes next?  The space shuttle built on NASA’s massively successful lunar landing program. But how does the organization build on a program with impressive but unused capabilities?

Speaking to Phil Christensen recently, I learned that Mars will be a priority in NASA’s upcoming plans. Without the shuttle, more funds will be potentially available to other goals – a single shuttle launch at about $450 million is nearly half the yearly budget given to all robotic planetary missions. A manned mission to the red planet might not be the next mission to launch from the Kennedy space centre, but increased attention to further planetary exploration is likely.

Perhaps a concrete goal will push NASA to focus its energy the way the lunar goal focused the efforts of the combined Mercury, Gemini, and Apollo programs. In the mean time, NASA’s astronauts may have to travel to Kazakhstan all suited up and stick out a thumb.

Buzz Lightyear prepares to go to infinity, and beyond!

Selected Sources/Suggested Reading

Thanks to Phil Christensen, principle investigator of the 2001 Mars Odyssey Thermal Emission Imaging System (THEMIS) instrument and the Thermal Emissions System (TES) instrument on the Mars Global Surveyor. Meetings with him have brought up some interesting points.

“NASA – Shuttle Missions” http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/list_main.html [Accessed February 25, 2011]

“Space Shuttle Launch Archives” http://science.ksc.nasa.gov/shuttle/missions/missions.html [Accessed February 25, 2011]

NASA Shuttle News Reference. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19810022734_1981022734.pdf [Accessed February 25, 2011]

T. A. Heppenheimer. Development of the Space Shuttle, 1972-1981. Vol. 2, History of the Space Shuttle. Washington: Smithsonisan Institution Press. 2002.

T. A. Heppenheimer. The Space Shuttle Decision. Vol. 1, History of the Space Shuttle. Washington: Smithsonian Institution Press. 2002.

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