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The Space Shuttle: NASA’s Astronaut Pod

An object that was said to launch like a rocket and land like a glider. For thirty years it was one of most recognizable transportation objects on the planet. Powering off its launch pad and into the sky above, it became a symbol of exploration and space travel. Involved in 135 separate launches, spread across five different shuttles it was the spacecraft from the early 1980s for the next thirty years.   

But the story Space Shuttle is also one of disaster, a tale marred by two of the most devastating and public tragedies to occur during our exploration of the cosmos. Needless to say, placing humans at the tip of what can only be described as a massive controlled explosion, is and always has been fraught with danger.  

Background

Perhaps the most significant aspect to focus on with the Space Shuttles was their reusability. Before their introduction, the majority of launch systems could be used once and only once. Understandably, in the early years of space exploration, the focus was on just making sure a vehicle could make it safely into space and back again, without too much thought of recycling. 

And in the early decades perhaps they didn’t really even need to. During the 1960s and 1970s, NASA’s annual budget fluctuated between $3 billion and $4 billion (roughly between $24.7 billion and $33 billion today) This was the heyday of U.S space exploration and one in which the government was more than happy to throw hefty sums of money at. By the mid-1960s, NASA was receiving roughly 4.5% of the total federal budget – admittedly this was a high point and it quickly came down after – but it does show us just how important the Space Race became to the Americans.  

But things began to change by the mid-1970s. As the Vietnam War dragged on, seemingly infinite budgets for the space program were no longer a given. The conflict in South-East Asia is believed to have cost the U.S in the region of $1 trillion when adjusted for inflation – a figure that dwarfs anything NASA ever did. 

When Apollo 11 landed on the moon on 24th July 1969 it was watched by an audience of roughly 650 million people around the world, including 53 million in the U.S. That was a staggeringly high number, but actually accounted for only about a quarter of the U.S population at the time, which begs the questions, what were three-quarters of the population doing when their country placed a human being on the moon for the first time? 

But when Apollo 17 touched down on the lunar surface in 1972, the number of those watching was only a fraction. It may have been difficult for many involved to admit, but the audience at home was becoming disinterested with space travel. This led to a significant tightening of the belt and one of the best ways to do this was to design a shuttle that could go into space multiple times.  

Development 

The idea of a reusable spacecraft had been bouncing around since the 1950s when the U.S Air Force began developing plans for a piloted glider that it could use for a variety of military purposes including, reconnaissance, satellite attacks, and air-to-ground weapons deployment. 

NASA soon became involved and the two agencies collaborated on the X-20 Dyna Soar. A program that ran between 1957 and 1963, costing $660 million ($5.51 billion today) and was cancelled shortly after construction of a prototype had begun with NASA choosing to focus on Project Gemini, the second human spaceflight program. If you’ve ever wondered why space exploration was so expensive in the early decades, this was a prime example.  

In 1966 NASA and the U.S Air Force announced jointly that a new space vehicle would be needed and in 1968 they went as far as to say that whatever came next had to be reusable. Shortly after, NASA issued a request for proposal (RFP) for what they termed as an Integrated Launch and Re-entry Vehicle (ILRV). 

Now, normally with these kinds of RFPs, companies are invited to submit a design along with a bid for the projected cost. Typically the organisation involved would then choose the best and a contract would be awarded from there. This one, however, was a little different with NASA broking the process into four phases.  

Phase A was a request for studies completed by competing aerospace companies 

Phase B was a competition between two contractors for a specific contract

Phase C involved designing the details of the spacecraft components

Phase D was the production of the spacecraft.        

In December 1968, the Space Shuttle Task Group was created and asked to establish the best design for a reusable spacecraft, while at the same time study contracts were delivered to General Dynamics, Lockheed, McDonnell Douglas, and North American Rockwell.  

This was not a quick process and it took nearly three years for NASA and the Air Force to determine that a reusable delta-wing orbiter mounted on an expendable propellant tank was the way forward. The following year President Nixon authorized the production of the Space shuttle, with North American Rockwell building the orbiter, Morton Thiokol responsible for the solid-rocket booster and Martin Marietta constructing the two external boosters. On top of this, the decision was made that the current F-1 and J-2 engines in the Saturn rockets would need to be updated and NASA contracted Rocketdyne to start work on a new engine, which would eventually become the RS-25. 

Enterprise

If the name Space Shuttle Enterprise sounds a little unfamiliar to you that’s because it never went into space. Enterprise, which formally began life as OV 101, was purely a test space shuttle and was not equipped with the heat shield needed for take-off or re-entry. 

Work began on the Enterprise in 1974 and was completed two years later before moving to Edwards Air Force base for testing. But if the construction of the orbiter was fairly brisk, the development of the new engine and the thermal protection system (the heat shield) were less so.

Engine development was initially held up for 9 months thanks to a legal challenge by Pratt and Whitney over the issuing of the contract. And even when things did get going the RS-25 suffered numerous problems with its nozzle and turbine blades. However, NASA must have been sufficiently satisfied because they ordered three more engines for the other orbiters under construction. 

The heat shield was another significant problem. The ablative heat shield that had been used on previous launches, and worked by pushing the shock layer gas away from the shield under extreme heat, was not reusable, so NASA instead went with the rather novel approach of ceramic tiles that could be individually replaced and were located around the upper forward fuselage, sections of the orbital manoeuvring system pods, vertical stabilizer and upper body flap surface. When I say tiles, it’s easy to think of kitchens and bathrooms, but these tiles could withstand temperatures of 1,260 °C (2,300 °F). They were 90% hollow and primarily formed of high purity silica fibres. Their distinctive black coating was the Reaction Cured Glass (RCG), which included tetrasilicide and borosilicate glass as well as other components.    

Enterprise underwent its preliminary testing at Edwards Air Force base with the aid of a modified Boeing 747, which would carry the Enterprise on its back. The first set of tests involved the Space Shuttle remaining attached to the 747 at all times, but by August 1977, it was detaching and gliding down to Earth on its own. After countless further tests which assessed its aerodynamic capabilities, vibrations on a simulated launch and how it would all fit together with the fuel tank and boosters, testing was completed in 1979. All that remained, was the real thing. 

First Launch  

While the Enterprise was being put through its paces, four further orbiters were in various stages of production. Columbia and Challenger would be the first to arrive, followed by Discovery and Atlantis. There was also a sixth Space Shuttle known as Endeavour, but after NASA decided to limit the number to four, work on this final shuttle was halted in 1983 – although it would recommence after the Challenger disaster. 

The first launch using the new Space Shuttle came on 12th April 1981 with the rather unimaginative name, Space Transportation System 1 (STS-1). Space Shuttle Columbia blasted off from the Kennedy Space Center in Florida at midday, carrying two astronauts; Commander John W Young and Pilot Robert L Crippen. 

The first test flight involving a Space Shuttle was hailed as a great success with Columbia orbiting the Earth 36 times and travelling 1,728,000 km (1,074,000 mi) in the process. The crew were able to test various components and equipment and a little over two days after its launch, the Columbia reentered the Earth’s atmosphere and landed safely at Edwards Air Force Base where they were welcomed home by none other than President Ronald Reagan – along with half a million spectators.  

But while the Columbia had made it up and down without any major incident, it was far from smooth sailing. In fact, there was a whole host of problems which had cropped up during the flight, ranging from tiles falling off, damage to the heat shield and even a small gas leak that had led to the buckling of the landing door (something neither astronauts noticed at the time and only discovered after reading the flight report). It was clear that while the basics of the new Space Shuttle were sound, there were plenty of tweaks needed. 

The Space Shuttle 

OK, before we continue with any more launches, let’s take a look at the Space Shuttle itself. The image that we see upon take-off is composed of the orbiter, one enormous external fuel tank and two solid rocket boosters – which aren’t exactly small either. 

The Orbiter included a crew compartment set over three decks; the first had the flight deck, which included panels with over 2,100 displays and controls, under that was the galley and sleeping quarters and below that the equipment deck where scientific instruments were stored as well as the waste management system. If I was feeling a little immature I might make a joke about this being the poop deck, but this is a serious video – so I won’t. 

Behind this area came the Space Shuttle Main Engines (SSME), comprised of three RS-25 engines and the Orbital Maneuvering System (OMS) with one AJ10-190 engine that allowed the crew to enter, exit and modify the shuttle’s orbit. The orbiter came with double-delta wings, swept back at 81° at the inner edge and 45° at the outer edge. In total, the Orbiter had a wingspan of 23 metres (78ft) and included elevons to control the shuttle’s reentry, which are those small flaps located at the rear of the wings. 

The vertical stabilizer (sometimes referred to as the fin on aircraft) stood at 45° and included a small rudder that could be split upon landing to act as a brake. If that wasn’t enough to slow the Space Shuttle down, there was also a two-part drag parachute system located in the vertical stabilizer as well as a conventional braking system in the landing gear. 

The monstrous external fuel tank that the Shuttle appears to piggyback on during take-off measured 47 metres (154ft) in height (slightly taller than the Statue of Liberty) and had a diameter of 8.4 metres (27 ft). It was capable of carrying an enormous 2.4 million litres (535,000 gallons) of propellants, comprising 1.7 million litres (390,000 gallons) liquid hydrogen and 660,000 litres (145,000 gallons) of liquid oxygen. To give you an idea of just how complex something like this was, the external tanks used on the Space Shuttles came with an extraordinary 480,000 separate parts, but funnily enough, was also the only part of the Space Shuttle that couldn’t be reused. Instead, after it detached it was directed towards the Indian or Pacific oceans with most of it burning up during re-entry.  

The two additional solid rocket boosters each measured 45 metres (149.2 ft) in height, had a diameter of 3.7 m (12.2ft) and provided 12,500 kN (2,800,000 lbf) of thrust, giving these boosters a thrust equal to 65 engines onboard the F-35 lightning in afterburner mode.  

They weighed 68 tons and came with a tough steel exterior measuring 13 mm (0.5 in) in thickness. Inside they were each filled with solid rocket propellant which added an extra 500 tons in weight. 

So now we know where everything is, how does it all work together? The process actually begins at the Orbiter Processing Facility (OPF) where the Orbiter is prepared before being attached to the fuel tank and boosters. The entire assembly is then transported to the launch pad on a crawler transport, an enormous contraption weighing 2,700 tons. 

The crew arrives roughly three hours before lift-off and the doors to the shuttle are closed two hours prior. Three minutes and 45 seconds before the launch the engine begins running through a series of tests and at 6.6 seconds before launch, the engines roar into life one by one with a gap of 120 milliseconds between them. As the countdown reaches zero, the eight frangible nuts which connected the boosters to the launchpad are detonated and the final umbilicals released. 

Roughly 123 seconds after launch, the two boosters disconnect and fall back to Earth, landing in the ocean where they are retrieved. The external tank has a burn time of around 420 seconds before the engine power is reduced and the tank disconnected. 

Reentry, strangely enough, begins with an upside-down, tail first orientation, with the OMS engine fired up for between 2 and 4 minutes. Afterwhich, the shuttle swings back around so it is nose first once again at a 40-degree angle as it begins its reentry, which NASA defined as being when the shuttle was at an altitude of 120km (74 miles) and travelling at Mach 25 (30,870 km/h – 19,181 mph). 

Eighth minutes and 44 seconds before landing, the shuttle angle is changed to 36 degrees with the landing phases commencing when the shuttle is at an altitude of 3,000 metres (10,000 ft) and travelling at 150 m/s. The angle is changed again to 18 to 20 degrees with the landing gear coming down ten seconds before landing. As the shuttle touches down on Earth once again, it is travelling at a speed of between 100 and 150 m/s (360 – 540km/h – 223 – 335 mph), after which the parachute deploys and is followed by the wheel brakes once the shuttle had slowed to a sufficient speed.  

The Shuttle Careers  

As I mentioned right at the start of the video, the Space Shuttles covered 135 separate missions – costing a staggering $450 million per launch. As a “cheaper” alternative, it wasn’t that cheap. The overwhelming majority of the Space Shuttle missions were completed successfully so it’s difficult to argue that the whole program was anything less than a success. 

Over the years they were involved in transporting equipment to the International Space Station as well as carrying the Hubble Space Telescope into orbit (and later its pair of spectacles needed to correct a previous error – and if you’re interested in that story you should probably check out our video on the telescope itself). 

But it doesn’t matter how many successful missions there are, you will still be judged on those that go catastrophically wrong. And the Space Shuttle program had two of those particular missions. STS-51-L was to be a space flight quite unlike any other. Keen to inspire a whole new generation, NASA had launched a ‘teacher in space’ project in 1984 which resulted in Sharon Christa McAuliffe, a teacher from Concord New Hampshire, being included in the seven-person crew on the Space Shuttle Challenger that lifted off at 4.38 pm on 28th January 1986. 

Just 73 seconds into the flight, Challenger suffered a fatal structural failure caused by both the primary and secondary O ring seals on the rocket boosters both failing. This quickly led to the disintegration of all four components and left the Orbiter hurtling back down to earth, killing all seven aboard the Challenger. With millions glued to television sets to witness the first teacher in space, including huge numbers of children, the accident was a harrowing visual image that left some wondering whether the Space Shuttle Program would even continue. 

 The program was grounded for two and a half years as investigators searched for the cause, while also trying to determine whether it was safe to fly again. The problem focused on the O rings, but also on the fact that the launch had taken place at temperatures of −3 °C (27 °F), well below the limit set for the boosters. It was a sobering time for all involved with the Space Shuttle, but on 29th September 1988, the Space Shuttle Discovery blasted off and four days later landed successfully.

Between 1994 and 1998, Space Shuttles visited the Russian Mir Space Station a total of eleven times, with American astronauts spending extended periods onboard. But that was nothing compared to the International Space Station, which involved 37 separate Space Shuttle visits over 13 years as the ISS slowly took shape.

But unfortunately, another tragedy was just around the corner. As the Space Shuttle Columbia began re-entry on 1st February 2003, to the general public there were no obvious signs of problems. However, flight control knew full well that the chances of a successful reentry hung in the balance. The heat shield had been compromised during take-off after a piece of the external fuel tank had come loose and damaged part of the wing. When the shuttle attempted re-entry, hot air began rushing into the shuttle which quickly disintegrated. Once again, all seven astronauts aboard a Space Shuttle lost their lives. 

Again, the fleet was grounded, this time for nearly three years as the investigation took place. It quickly became apparent that the foam shedding from the fuel tank had occurred before on previous missions but for whatever reason had never been fully corrected. NASA implemented much more stringent pre-flight safety checks as a result – which sounds a little strange to me because you would have hoped that they had been doing that all along.    

Retirement

The Space Shuttles were involved in 22 further missions without incident and on 21st July 2011, Space Shuttle Atlantis landed at the Kennedy Space Center and taxied slowly to a waiting hangar where it was greeted by a huge crowd. The age of the Space Shuttle was over. 

Despite the two tragic accidents, the Space Shuttles were incredibly reliable vehicles when you think about how many times they were used. Unfortunately, the projected cost and turn-around time proved to be wildly inaccurate. While costs may not have been quite as enormous as during the 1960s, the cost of the Space Shuttle program was still huge – thought to be roughly $196 billion (adjusted for inflation). 

Then there was the turn-around time. NASA had envisioned a space vehicle that could quickly and easily transport people and equipment into space, perhaps with periods as a little as a week or two in between. In reality, the fastest that was ever achieved by 54 days. 

While the Space Shuttles were certainly not perfect, they remain an iconic image. Their role in the development of how we put people into space is undeniable and it’s difficult to imagine how long the ISS would have taken without them. They also helped to rekindle interest in space that had begun to lag during the 1970s, but with the two high-profile tragic incidents, there is also somewhat of a shadow cast across the Space Shuttle program. They were, and in many ways still are, symbols of both the wonder and horror of space travel.      

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