Platinum use in science extends beyond measurement standards
Platinum and platinum group metals are widely used in advanced scientific instrumentation because of their unique combination of chemical inertness, thermal stability and resistance to degradation – characteristics that help maintain accuracy and performance over long periods.
The World Platinum Investment Council (WPIC) asserts that the role of platinum in scientific discovery extends beyond measurement standards, noting that it is also helping scientists observe phenomena at the very limits of human understanding.
The WPIC notes that the Laser Interferometer Gravitational Wave Observatory (LIGO) made history in 2015 with the first direct detection of gravitational waves – ripples in space-time first predicted by Albert Einstein almost a century earlier.
An interferometer is a scientific instrument that splits a beam of wave energy, such as light, radio or sound waves, into separate paths and then brings them back together to create an interference pattern.
LIGO is comprised of two separate infrared laser interferometers about 3 000 miles apart. Located in the US, the WPIC explains that each interferometer has two arms, 4 km in length, arranged in an ‘L’ shape. The interferometers work in unison, using mirrors to direct the paths of laser beams as they travel down each arm.
It is minute changes in the length of the paths of the laser beams that indicate the presence of a gravitational wave.
LIGO’s interferometers can detect distortions thousands of times smaller than a proton, requiring components and systems engineered to unprecedented levels of stability and precision.
Within the interferometers, the WPIC explains, platinum-based resistance temperature detectors are used to monitor the temperature of the mirrors to ensure they are sufficiently heated to maintain their carefully calibrated curvature before the laser beams are directed down each arm.
Earlier this year, the WPIC points out, engineers and scientists at the National Aeronautics and Space Administration (Nasa), completed tests in relation to the Laser Interferometer Space Antenna (LISA) mission, which is in planning for launch in the mid-2030s.
While LISA and LIGO are both gravitational wave observatories, the WPIC says the LISA will be a space-based observatory consisting of three spacecraft. The three LISA spacecraft will fly in a vast triangular formation that follows Earth as it orbits the Sun.
Each arm of the triangle will stretch 1.6-million miles, or 2.5-million kilometres, and each spacecraft will contain two free-floating cubes inside called ‘proof masses’.
The cubes comprising the proof masses are made of a solid gold/platinum alloy. Each cube has sides of 4.6 cm and weighs 1.96 kg.
“Arriving gravitational waves from throughout the universe will minutely change the lengths of the triangle’s arms. The lasers connecting the cubes will measure changes in their separation to within a distance smaller than a helium atom,” the WPIC explains.