Mon, 01 June, 2020
NASA’s SpaceX Demo-2 mission to validate the SpaceX crew transportation system was launched yesterday.
This end-to-end test flight will pave the way for the certification of regular crew flights to the International Space Station, and technology developed by TWI has played an integral role.
The astronauts who completed the mission are being transported using a crew capsule that was fabricated using TWI’s Friction Stir Welding technology – a joining technique which was invented and developed by TWI in 1991.
Although the two-stage SpaceX Falcon 9 rocket has flown 83 times for NASA and other agencies, this is the first time it has had astronauts aboard, making SpaceX the first commercial company to send people into space. The Falcon 9 and the Dragon spacecraft were designed to deliver humans into space, which has now been achieved.
The Falcon 9 incorporates nine Merlin engines and aluminum-lithium alloy tanks containing liquid oxygen (LOX) and rocket-grade kerosene (RP-1) propellant in its first stage. These first-stage engines are gradually throttled towards the end of the first stage of flight to limit acceleration as the mass of the vehicle decreases with the burning of fuel. The Falcon 9 is capable of generating over 1.7 million pounds of thrust at sea level, which increases to 1.8 million pounds of thrust in the vacuum of space. The second stage relies on a single Merlin engine that also runs on LOX and RP-1.
70 metres high and 3.7 metres in diameter, Falcon 9 is the first orbital class rocket capable of reflight, meaning that the first stage booster can be reused after use by landing it on a SpaceX drone ship waiting offshore.
This latest achievement builds on previous uses of the TWI-developed welding technique by engineers at SpaceX.
Another milestone for space exploration was achieved on 6 February 2018, with the launch of Falcon Heavy from Kennedy Space Centre in Florida. The craft, which was created by U.S. entrepreneur Elon Musk’s SpaceX programme, was at the time the most powerful operational rocket in the world.
The rocket used Friction Stir Welding (FSW) in its design, a friction joining process that was invented at TWI in 1991 and has since gone on to be used for a variety of applications, including the joining of fuel tanks for the now decommissioned space shuttle.
The FSW process is not only faster than many other joining methods but also offers better properties, while the lack of riveting, for example, also lowers the weight of the final product, making it ideal for aerospace and astrospace applications.
Falcon Heavy is able to lift 64 tonnes into orbit – the equivalent of five double-decker buses – which is just over twice the weight that can be lifted by the second-most powerful operational rocket, Delta IV Heavy. This payload means that Falcon Heavy offers increased possibilities for SpaceX, including the launch of bigger satellites for U.S. intelligence and military, launching large batches of satellites (i.e. to help deliver global broadband), sending bigger robots to Mars or the outer planets of Jupiter, Saturn and their moons, and the transportation and launch of huge telescopes.
Comprised of three Falcon 9 engine cores with the ability to deliver five million pounds of thrust at lift-off, the Falcon Heavy is also just one-third of the cost of the Delta IV Heavy. This saving is due to the fact that the boosters from the SpaceX rocket can be recovered and reused.
However, this first mission saw a much lighter payload than is possible delivered into space as Elon Musk decided to send his red Tesla sports car into orbit, complete with a space-suited mannequin in the driver’s seat and David Bowie’s 1969 hit ‘Space Oddity’ playing on a loop on the stereo!
You can find out more about TWI’s work with Friction Stir Welding here.