The Thermo IRMS 253 Ultra (IMAGE) California Institute of Technology Caption The Thermo IRMS 253 Ultra is Caltech's prototype mass spectrometer, which enables John Eiler and his team to determine formation temperatures for methane samples. Credit Caltech Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.