What is Ptolemy?

Ptolemy, pronounced with a silent P and always capitalised, is one of the latest innovations in space technology. This ingenious instrument is designed to analyse the isotopic makeup of solar system bodies whilst in situ in space. The concept to which the instrument belongs is a new way of exploring celestial properties and is termed MODULUS, named for Thomas Young, the man famous for his theory of elasticity known as Young’s Modulus.

When spelled out in full, MODULUS means Methods Of Determining and Understanding Light elements from Unequivocal Stable isotope compositions.

Ptolemy is one of the most advanced instruments which belong to this concept, and aims to analyse the distribution of geochemical elements in light compositions. Namely, it will identify the stability, distribution and nature of carbon, hydrogen, nitrogen and oxygen in comets and the suchlike while in space.

The Aims of Ptolemy

The Ptolemy instrument was designed in order to solve a number of specific challenges faced by scientists while trying to gather in situ data from bodies in space. The challenges are:

• Compare and contrast the water and ice found on comets with bodies of water on our planet
• Understand the fundamental cosmochemical makeup of comets
• Determine the exact balance of volatile internal elements on a comet
• Explain the nature of organic compounds found on a comet
• Compare and contrast these organic compounds with similar substances from other sources, whether they be on Earth, other planets, satellites or asteroids
• Work out the amount of low temperature mineral elements on a comet and estimate the history of their formation
• Note down specific characteristics of refractory minerals with high temperatures
• Investigate the effect that comets have on planetary evolution and other phenomena of the Solar System

How Ptolemy Works

The Ptolemy instrument is no bigger than a shoebox and will function in situ in space. After samples have been collected by the SD2 drilling system, which will harvest ice and dust from near-surface areas and sub-surface depths of up to 20cm, solid samples are delivered to Ptolemy’s four ovens. Once the oven is heated, the volatiles are released into the analytical system and are purified and identified.

They are then assessed using a combination of gas chromatography and mass spectrometry (GC-MS) in an ion trap mass spectrometer. Mass spectrometry has become an increasingly important tool in all manner of scientific fields, including many far more run of the mill than Ptolemy. For more information on how alterations to the technique have made it more adaptable to modern science, check out the article Mass Detection for Chromatographers: How New Technology is Changing the Way We Think about Mass Spectrometry and its Use in Routine Workflows.

As well as separating the sample out into its various compositional gases and quantifying and identifying each one, the ion trap mass spectrometer will also serve to measure the ratio of stable isotope properties in the sample. What’s even more impressive is that all of this will be conducted in situ on the comet itself. The data can then be relayed back to Earth to help us understand more about comets and their effect on the universe.