1. What? Main objectives: What is the origin of water on Earth? How do terrestrial planets accumulate volatiles? Spin-off Science: What is the composition of comets and Kuiper Belt objects? Distribution of chemical abundances in the outer Solar Nebula?

2. Why? D/H ratio puzzle: accretion or comets? Corellation between different chemical abundances? Constraining initial conditions for numerical accretion models: –Temperature and pressure gradient. –Chemical and density gradient.

3. How? Mini-satellite mission for in situ measurements (mass spectrometer). Ground-based or space-based radio spectroscopy. Measurements of comets with different types of orbital characteristics.

4. Abstract It is crucial for the field of astrobiology and the understanding of the origin of life on Earth to determine the origin of water and other volatiles on terrestrial planets. A possible explanation for the origin of water is due to delivering of cometary impacts. This is contradicted by observation of the D/H ratio from two comets which is higher by a factor of two than what is observed in the oceans of the Earth. In order to constraint the initial conditions (temperature, pressure, chemical, and density gradients) for numerical simulations of the protosolar nebula, we will determine the current distribution of volatiles in comets and Kuiper Belt objects. We will accomplish this using ground-based radio spectroscopy to measure the relative abundances of isotopes in volatiles as well as track the orbits of the studied objects. In addition a suite of low-cost mini-satellites will carry mass spectrometers for in situ measurements of comet material travelling through the comet tails. Group 2: Karen, Irina, Jeanette, Tobias, Aleksi, Jaakko, David Field, and Minik Rosing