If you’ve read our recent Canvas Originals story about NASA Electrical Engineer Jeff Sincell and his use of Canvas technical illustration software in the design and creation of four incredible NASA space machines, you may have wanted to know a little more.
What went wrong with the Mars Observer? Why does the James Webb Space Telescope have a warm and a cold side…?
Jeff gave us some extra depth.
The cause of the loss of Mars Observer in 1993 was subject to a painstaking investigation in order to ensure the problem did not reoccur.
As Jeff remembers it, the conclusion was that a propulsion anomaly occurred as the spacecraft was preparing to go into orbit around Mars, for which it had to burn its main engines to slow down. The craft had the two most energetic chemicals available for rocket fuel. So hyperactive are these two chemicals that they burst into flames the moment they touch one another.
The TIROS platform on which the spacecraft was built had a propulsion system designed to activate within hours of launch, but Mars Observer traveled for nearly a year before pressurizing its fuel system, during which time one of the fuels had been able to diffuse through a check valve and condense on the other side.
This was disastrous when the propulsion system was activated because the two fuels touched in the plumbing before they got to the engine and a small but fatal explosion occurred inside the fuel line.
The resulting pressure leak spun the spacecraft out of control and it whizzed past Mars and is likely still spinning in an orbit around the Sun.
Jeff is now working on the the James Webb Space Telescope, which is expected to launch next year. When the project began, he says, “the lead systems engineer said we needed to understand every single wire going from the warm side to the cold side of the telescope.”
So what does that mean?
As Jeff explains, heat and light are just different frequencies of the same form of energy. JWST is designed to “see” heat because that is what the visible light from distant stars and galaxies becomes as it travels through space – its frequency becoming lower and lower the further it goes.
So the detectors on the telescope must operate at as cold a temperature as possible or they would otherwise see the heat radiating from the spacecraft. This is prevented by the harness design as well as a huge heat shield that also keeps the Sun’s heat at bay, resulting in the detectors and surrounding optical equipment running at 400 degrees below zero Fahrenheit.
The rest of the spacecraft operates at room temperature, meaning the machine has cold and warm sides. As a result, the wires traversing the thermal “wall” are specially designed to conduct as little heat as possible, while still allowing the electrical equipment to work.
Jeff’s technical illustration of the wiring system for JWST has taken 20 years to reach maturity and contains almost 30,000 separate objects, which might just be the most complex drawing we’ve ever heard of anyone creating in Canvas!