LISA's voyage into Space: Time to fill up the tanks

As the loading of the propellant into the spacecraft propulsion module tanks takes place ready for launch, I caught up with members of the team responsible for undertaking the hazardous task of loading the fuel…

Q: What fuel are we loading into the propulsion module?

A: The LPF PRM has a bi-propellant system which means we have an oxidiser and a fuel. As with many spacecraft, the oxidiser is NTO (a mix of Nitrogen Oxides) and the fuel is MMH (Mono-methyl Hydrazine).

Q: Its sounds like a dangerous job, how dangerous is it?

A: This is by far the most dangerous activity that the team face. The fuel is toxic so we have to take measures to ensure we don’t come into contact with it directly as it can cause chemical burns and anoxia (which is a severe lack of oxygen in your system that in this case could occur if there was a leak in the atmosphere, especially as the oxidiser has a boiling point of approx. 21degC). The risks are mitigated by the use of special suits which are worn by those undertaking the loading of the propellants. In addition there are a number of safety features built into the design of the spacecraft to ensure that the oxidiser and the fuel don’t inadvertently meet each other during ground operations. In addition there is constant monitoring of the level atmosphere in the facility to ensure any potential leaks are quickly detected and contained.

Q: Tell us more about the SCAPE suit you have to wear – you look like a deep sea diver, or an Astronaut?!

A: SCAPE stands for Self Contained Atmospheric Protection Ensemble. It protects the propellant loading team from coming into contact with hazardous and toxic propellants. It provides a positive pressure inside the suit to ensure no toxic vapours can enter and protects any liquid propellant coming into contact with your skin. Underneath we wear a fetching cotton onesie as the suit itself is basically plastic. Over the onesie we wear a vest containing our communications equipment. The suit is finished off with a pair of plastic boots and a helmet.

Q: What is it like working in a SCAPE suit?

A: Working in a SCAPE suit can be very hard work if you have to do a lot of movements, the suits are quite heavy and hence we prepare the facility in advance so minimum effort is required in the suit. We set out all equipment and ensure the area is clear of as many obstructions as possible. These suits are very safe but become very uncomfortable after 5 hours in them. We also have a team in the control room that dictate all commands to the team in the facility; these are then repeated and performed. In addition, they will often ask us to solve a few brain teasers and puzzles, just to check we are still OK.

Q: What will you do after the fuelling is finished?

A: Relax and have big BBQ for the team!

After the loading activities we have to decontaminate our loading equipment to make it safe for transport back to the UK. Some of this activity is carried out in what is called a Splash suit and breathing apparatus, when we have to disassemble the different parts. We have to flush the system with demineralised water to neutralise the oxidiser and fuel. After this the equipment is purge dried with nitrogen ready for shipment to the UK. This process reduces the ppm (parts per million) level of propellant in the equipment so that it complies with safe levels for transportation.