Despite lifting off 135 times, making an appearance in a Bond film, and even its immortalisation in Lego, the famous space shuttle is taking early retirement. On 8 July 2011, the Atlantis orbiter will embark on the very last space shuttle mission bringing NASA's shuttle programme to an end after 30 years. It's the end of an era, both for space exploration and for technology, so it seems only fitting to look back over the life and times of the space shuttle, the amazing gadgets and gizmos that make her go and find out why the programme is coming to an end and what happens next.
Firstly, let's deal with the basics. What is the space shuttle? Well, it was the first reusable orbital space craft, unlike the old Saturn V rockets as used in the Apollo missions (including the moon landings) that could only be used once. The concept of a spacecraft returning and landing horizontally, like a plane, was born in the 1950s, although development of the space shuttle didn't actually begin until the 1970s, after the US National Aeronautics and Space Administration (NASA) was given the official go-ahead by president Richard Nixon in 1969.
Some of the Star Trek cast at the Enterprise dedication ceremony
The final frontier
The very first space shuttle orbiter was named Enterprise and was designed to perform test flights in the Earth's atmosphere, so it was never actually ready for spaceflight. Construction began in 1974 and it first took to the sky in 1977. Supposedly, the shuttle was originally going to be called Constitution but was re-named following a campaign by Star Trek fans who thought that it should be named after the Starship Enterprise. Serving US president Gerald Ford said that he was "partial to the name", but that may have had more to do with the fact that he spent much of his WWII naval service on aircraft carrier USS Monterey, which served with the famous USS Enterprise, the most decorated warship in the conflict. However, adding some weight to the sci-fi story, or at least making full use of the publicity that it generated, Star Trek creator Gene Roddenberry and a fair number of the cast were present at Enterprise's dedicaton ceremony.
The next step in the saga was the construction of the first space-ready shuttle, Columbia, which took its first orbital flight on 12 April 1981 - 20 years to the day after cosmonaut Yuri Gagarin became the first human in space in Vostok 1. Columbia flew a total of 27 missions before it tragically disintegrated on re-entry to the Earth's atmosphere in 2003.
The second shuttle to join the fleet was Challenger in 1983, followed by Discovery in 1984 and Atlantis in 1985. Endeavour was added to the lineup in 1992 to replace Challenger, which was destroyed in a disaster six years earlier. Unlike the Enterprise, the space-ready shuttle fleet orbiters were all named after sailing ships from around the world and are almost identical. There are minor difference in the interiors, with the newer orbiters containing a few advanced structural elements, resulting in slighter larger cargo capacity.
Discovery taking off on its final mission
Components of the space shuttle
The space shuttle comprises three main components - two Solid Rocket Boosters, the External Tank and the Orbiter Vehicle (OV) itself. Roughly the same size and weight as a DC-9 aircraft, the orbiter is crafted mainly from aluminium alloy, measures 37.23m long with a wingspan of 23.79m and weighs a humungous 80 tonnes - and that's when it's empty. The orbiter is made up of the aft, mid and forward fuselages - the aft fuselage is home to the three main engines while the mid fuselage is where the payload (cargo) bay is located, along with the Remote Manipulator System (RMS) - a 15.2m long articulating arm, which is operated by remote control and used to manoeuvre the payload. The forward fuselage is home to the crew module which consists of the flight deck, middeck and airlock.
The orbiter is attached to the two Solid Rocket Boosters (SRBs) which provide 80 per cent of the launch thrust and contain more than 450 tonnes of propellant each. These operate alongside the main engines for the first two minutes of flight to get the shuttle off the ground. Once the shuttle is about 45km up in the air, and almost at the upper reaches of the Stratosphere, the SRBs are the first pieces of the setup to be jettisoned after which they descend on parachutes before plunging into the Atlantic. They're then recovered, returned to land and refurbished to be used again.
The orange-coloured External Tank (ET) provides the liquid oxygen and hydrogen fuel to the shuttle's main engines during liftoff which burn through 0.5 million gallons of the stuff during acceleration. The tank is ditched mid-air, after about 8.5 minutes once all the propellant is used and the shuttle has reached a speed of about 17,500 mph (7.8km/s). It's the only component not to be re-used as it largely burns up in the atmosphere after each launch.
Once the ET has been dumped, the shuttle uses the orbital maneuvering system (OMS) - which is pronounced like homes, minus the h - to adjust the orbit. This is a system of rocket engines comprising two thrusters, located in two pods in the aft fuselage, that can also be used to manoeuvre the shuttle during missions or at the end of each flight in order to drop out of orbit and re-enter the Earth's atmosphere.
En route to the launchpad on the Mobile Launcher Platform (MLP)
The three main components of the shuttle are put together in the massive Vehicle Assembly Building at Kennedy Space Center (KSC). At 160.3m high, this is the tallest single story building in the world and was originally built for the vertical assembly of the Saturn V rockets, as used for the Apollo missions. Once all three components of the shuttle are put together, it's taken to the launch pad on the Mobile Launcher Platform (MLP) - an enourmous transporter which travels on caterpillar tracks, like a tank. Once in place, this two-storey structure is also used as the shuttle's launch platform. Each MLP measures a whopping 49 x 41 x 7.6 m and tips the scales at a heavyweight 3,730 tonnes.
Most missions land back at the 4,600m concrete runway at KSC - to put that into perspective, that's the length of more than 40 football pitches put together. If weather is bad then there are two alternatives landing sites. The primary back-up site is Edwards Air Force Base in California which has seen nine landings, split between its concrete and dry lakebed runways, while one mission landed at the second backup location at White Sands Space Harbor, New Mexico, in 1982. When shuttles end up at one of the alternative landing sites, they are taken back to base by piggybacking on one of two specially modified Boeing 747 airliners, known as Shuttle Carrier Aircraft. There are also various other potential emergency landing sites around the world, which are designated as no-fly zones during each launch.
Endeavour hitching a ride home on the Shuttle Carrier Aircraft
Scary as it sounds, each shuttle flight relies heavily on the on-board computer system. With such a complex piece of machinery involved and with safety being of paramount concern, a five-computer system is used so that if one of them fails, the others can carry on safely. The shuttle orginally used five worryingly dated-sounding IBM 32-bit computers (model AP-101), with four running the Primary Avionics Software System (PASS). The fifth computer is there for backup and runs different software known as the Backup Flight System (BFS). All five computers together are known as the Data Processing System (DPS).
Avionic software is developed under completely different conditions to the consumer software that we all know and love (or possibly hate), with numerous engineers working on the same tiny piece of code and testing it rigorously. It's all written in HAL/S - an aerospace-specific programming language, based on IBM's PL/1 language. Despite the precision, it's still possible that a general software problem could crash all four of the main computers, leaving the backup model to do the work. Thankfully, this has never happened on a shuttle flight.
The original IBM AP-101 computers used on the shuttle had magnetic core memories of around 424KB each. There was no hard disk and software was loaded from magnetic tape cartridges. These were replaced with the upgraded AP-101S model in 1990, which brought with it a larger (but still slightly laughable) 1MB memory, along with higher processing speeds, while the magnetic core was replaced with a semiconductor memory with battery backup.
The GRiD Compass laptop on board Discovery in 1985
Earlier shuttle missions also made use of the GRiD Compass - widely considered to be the very first laptop computer. This modified laptop was catchily dubbed the Shuttle Portable Onboard Computer (SPOC). Since 1993, the IBM ThinkPad (now owned by Lenovo) has been the regular on-board laptop for shuttle missions and is the only laptop certified for use on the International Space Station (ISS), where there are around 100, although Macs and other laptops have been used on occassion for specific experiments. On the ISS, the laptops are hooked up to the station's LAN via Wi-Fi, and are connected to the ground at a speed of 3Mbps up and 10Mbps down. As far as we know there's no such capability on the space shuttle.
Tweeting from space
It was this LAN that enabled Mike Massimino (@Astro_Mike) to become the first person to Tweet from space back in 2009, when he wrote “From orbit: Launch was awesome!! I am feeling great, working hard, & enjoying the magnificent views, the adventure of a lifetime has begun!”. However, it wasn't until 2010 that NASA installed new software enabling astronaut Timothy Creamer (@Astro_TJ) to send the first live Tweet from space (the previous one was "assisted", going via email to Johnson Space Center, and so not technically live). The new software also enables astronauts on the ISS to browse the web and communicate with their loved ones, although they're bound by the same rules as government employees on Earth, so accessing any 'inappropriate' sites isn't allowed.
Up until 2001, astronauts could only speak to their loved ones via the radio at mission control but all that changed when astronaut Marsha Ivin made the first phone call from space, using the Softphone. This IP system hooks up to the on-board laptop and transmissions are then sent over a distance of up to 44,810km, via satellite, with calls usually seeing a time lag of around one second.
Along with the usual laptop, the final shuttle mission will carry a pair of space-certified iPhone 4s running the experimental SpaceLab app, which you can pick up on iTunes. The phones will be dropped at the ISS, where they'll spend several months before being returned on a Russian Soyuz. Among other things, the app will let the astronauts pinpoint their location using the camera and the in-app coastline database. The data collected will also be used to assess how well the iPhone withstands the harsh environment of space flight. Although you can pick up the app and run some of the functions here on Earth, not all of them will work as they're designed for use in space. However, it's a great way for the geeks among you to get in on the action.
Naturally, the space shuttle has seen plenty of other technical upgrades over the years including the move from analogue flight instruments to a 'glass cockpit', featuring colour flat-panel displays as found on modern airliners, and allowing for all the usual readings such as altitude and speed. The flightdeck of each shuttle has the usual pilot/co-pilot set up that you'd find in a plane, so that the orbiter can be piloted from either seat and can be flown by one person in an emergency. Each seat has manual flight controls (including a games console-style joystick controller), rudder pedals and speed-brake controllers. In total, there's a baffling array of more than 2,020 separate displays and controls on the flightdeck.
The shuttle also features a forced air convection oven and water dispenser used for warming and rehydrating food. Space food has come along way since the first manned missions and astronauts can now choose their own menus in advance (although they have to be approved by a dietician). As you'd expect, a lot of the food comes in sealed packets which need to snipped open using scissors before being rehydrated or warmed up, but some of it, such as fruit, can be eaten in its natural form. Condiments, such as ketchup and mustard are supplied, along with liquid salt and pepper, designed for use in microgravity. Meals are stowed in locker trays where they're held in place using nets and velcro to prevent them from floating around the cabin. Velcro is also used to hold food packets onto trays, while magnets are used to secure cutlery.
Weightlessness effects all of the everyday tasks carried out by the astronauts, as they spend much of the time floating around in the air. However, they can use the restraints to strap themselves into seats and they're zipped into sleeping-bag style beds to sleep, while the space shuttle toilet (euphemistically dubbed The Waste Collection System) uses an airflow system, in place of gravity, to draw waste down. Liquid waste is then vented into space, while solid waste is vacuum dried and hygienically stored for disposal on return.
While the astronauts are working for the majority of the time, they do get to relax as well, although there's no TV on the space shuttle. However, major news events (including President Obama's inauguration) have been beamed up to the ISS from mission control, although a constant signal isn't possible as the station is in orbit around the Earth. A lot of the astronauts now take iPods with them on missions, although NASA apparently insists on the use of an AA battery convertor as the built-in batteries aren't approved for space travel. Before the iPod, astronauts took personal CD players into orbit with them.
While Hassleblad cameras were famously used on the Apollo missions, including the moon landings (in fact 12 Hassleblad cameras are still sitting on the lunar surface), all sorts of cameras have been used since - both on the space shuttle and at the ISS. Nikon developed a space-friendly F camera for NASA back in the 1970s, while its 12.1MP professional D3S DSLR is the most recent model to make it into space after the Administration ordered 11 of them for the ISS in 2009. Models from Kodak (including the 6 MP DCS760) have also been used on shuttle missions.
Possibly the least technical development in the space shuttle programme was the use of owl decoys to deter pesky birds from the launchpad after the 1995 Discovery flight was delayed due to woodpeckers making holes in the ET's foam insulation.
The International Space Station (ISS)
It all sounds very impressive, but what benefits do we get from the space shuttle missions? As well as the direct objectives of each mission, such as the building of the International Space Station and maintenance of the Hubble Space Telescope there are plenty of other innovations to come out of space travel ranging from non-scratch lenses to water filters. Contrary to popular belief, velcro wasn't created by NASA - it was actually a Swiss invention from the 1940s that was made famous by its use in the Apollo missions. Other useful developments include improvements in hydroponics and the invention of ear thermometers for instant temperature readings.
In 1973, NASA began to publish an annual report of its inventions that had made it into commercial products and in 1976 this became a magazine called Spinoff.
The space shuttle may be a hive of technical innovation, but what about the ludicrous amounts of cash involved? Each launch costs around $450 million, while the newest shuttle in the fleet - Endeavour - cost $1.7 billion to build. And with the total cost of the space shuttle programme estimated to be around $174 billion, launching people into orbit isn't a cheap business and has understandably garnered a fair amount of criticism, particularly during recent recessionary times. The space shuttle has also been criticised in terms of safety - despite the fact that well over 100 successful missions have been carried out safely - the fact that two out of five orbiters have perished, killing all on board, isn't a good safety record by any margin.
The crew from the 1986 Challenger shuttle disaster
The first disaster happened on 28 January 1986 when Challenger, the second shuttle to join the fleet, broke apart 73 seconds after take-off, killing all seven crew members. The accident was caused by a defective O-ring seal in the right Solid Rocket Booster which kicked off a chain reaction of technical failures. While the shuttle was built to withstand a load pressure of 3g, it rapidly disintegrated after reaching 'Max Q' - the maximum amount of aerodynamic stress that a vehicle in atmostpheric flight can handle.
On 1 February 2003, the oldest space shuttle - Columbia - disintegrated over Texas during its re-entry to the Earth's atmosphere, once again killing all seven crew members on board. This was the result of a piece of foam insulation from the external tank becoming dislodged during take-off. This hit the edge of the left wing, damaging the shuttle's Thermal Protection System (TPS). The TPS covers the shuttle chassis and is designed to protect it from the temperatures of -121°C in space and the intense 1649°C heat of re-entry.
The crew from the 2003 Columbia shuttle disaster
Following the second tragedy, a report published by the independent Columbia Accident Investigation Board was critical of NASA's risk assessment procedures and made recommendations that included more pre-flight inspection routines. Many of the recommendations served to highlight the fact that the aging shuttle should be replaced by a more modern spacecraft.
While Discovery and Endeavour both completed their final flights earlier in 2011, Atlantis will be the star of the very last space shuttle mission. The fourth shuttle to join the fleet at Kennedy Space Center, Atlantis has made 32 flights (prior to its final mission), travelling a total distance of 120,650,907 miles and spending a total of 293 days, 18 hours, 29 minutes and 37 seconds in orbit. In its 26 years of flying, Atlantis has been home to 203 crew members, made 4,648 orbits, made 18 space station dockings (seven with the Russian Mir station and 11 with International Space Station) and deployed 14 satellites.
As with all the previous flights, the final mission (STS-135) will take off from Kennedy Space Center (KSC) in Florida, but what it's actually for? The main cargo (or 'primary payload') will be the Raffaello multipurpose logistics module which will contain supplies and spare parts for the International Space Station. Other mission objectives include investigating the potential for robotically refueling existing spacecraft as well as returning a failed ammonia pump, so that NASA can figure out what went wrong and improve the design for the future.
Atlantis on the launch pad for the very last time
Missions tend to last from 5-16 days (the longest being 17.5), with the final Atlantis trip planned to land on 20 July after 12 days. The four-man crew will take off from KSC launch pad 39A at 11.26am EDT on Friday 8 July. This will be the 82nd shuttle launch from pad 39A, while pad 39B managed to clock up just 53 launches before it was decommissioned on 1 January 2007. It is now being offered to private companies for commercial space flight, while the future of launch pad 39a is uncertain.
What happens next?
This may be the end of the road for the space shuttle, but what happens next? The initial plan was to replace the shuttle with the Orion spacecraft, which was to be paired with the rocket-shaped Ares 1 launch vehicle. Developement on Orion began in 2005, as part of the Constellation programme - the plan being to send astronauts to the moon, then Mars and beyond. However, when President Obama signed the NASA Authorization Act 2010 on 11 October 2010, the Constellation programme was brought to a halt. Despite promising NASA $6 billion over five years, the Obama administration has received a substantial amount of criticism (most notably from ex-astronauts Neil Armstrong and Jim Lovell) for cancelling the programme and wasting the money that has already been spent.
The Multi-Purpose Crew Vehicle (MPCV) - previously known as Orion
With the Ares I ditched, the Orion has now been snappily renamed as the Multi-Purpose Crew Vehicle (MPCV) and is set to be paired up with the new Space Launch System (SLS) launch vehicle. Bearing more of a physical resemblance to the old Apollo modules, the MPCV will carry up to four crew members and will be the only part of the new system that is re-used after each flight. No exact dates have been set, but the maiden voyage for the new system is tentatively pencilled in for 2016.
Until then, with no means of its own to launch astronauts into space, NASA has signed a $753 million deal with Russia in return for 12 flights to and from the ISS between 2014 and 2015 - which works out at around $63 million per seat.
Virgin Galactic's SpaceShipTwo
By the time the new MPCV spacecraft takes off, there may also be the possiblity of commercial flights into space. Richard Branson's Virgin Galactic is already taking bookings for flights although with tickets costing $200,000 and deposits starting at $20,000, it's strictly for high-rollers only. A launch date has yet to be confirmed for the first trip, although Branson has already teamed up with The Spaceship Company to put the SpaceShipTwo and the White Knight Two into commercial production.
While the end of the shuttle programme is nigh, and it's now too late to witness a launch, you will still be able to see the orbiters themselves up close and personal. Atlantis will be on show at the Kennedy Space Center Visitor Complex in Florida, while Endeavour will be making its way to the California Science Center in LA. Enterprise is currently at the Udvar-Hazy Center of the Smithsonian Institution's National Air and Space Museum in Chantilly, Virginia, near Washington D.C, but when Discovery arrives, it will be moved to the Intrepid Sea-Air-Space Museum in New York City.
Despite the gargantuan expense involved, as well as the tragic loss of life, the space shuttle will be remembered as one of the most impressive technical innovations of the 20th century. We look forward to seeing NASA's next-generation spacecraft taking off in 2016 or soon after.
What do you think of the space shuttle? The height of technical innovation or a big 'ol waste of money? Let us know in the comments box below.