About the mission

Water is one of the most important chemical compounds needed for the development of life. Water molecules are also widely present in the universe, being the main component of comets. However, direct observation of cometary water is very difficult.

“It is much easier to observe hydrogen atoms released in the gaseous envelopes of comets due to the decay of water molecules”, said Michal Drahus, HYADES principal investigator.

These atoms emit a very large amount of light through the so-called Lyman alpha line, making them an extremely sensitive tracer of cometary water – both the ordinary water and its heavier variants, whose presence is evidenced by deuterium – the only stable isotope of hydrogen. However, observation of the cometary Lyman alpha line is also very difficult, since it is in the far ultraviolet range and is completely absorbed by Earth’s atmosphere. To solve this problem, as part of the HYADES (HYdrogen And DEuterium Survey) a new satellite will be specifically designed to observe the Lyman alpha line from space, outside Earth’s atmosphere.

Science background

New water reservoirs

Origin of water on Earth

Interstellar objects

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