In February our bloggers were at LPSC reporting on the Decadal Survey that sets out NASA’s planetary exploration priorities for the next decade. Top of the list was a Mars rover and a Mars sample return mission. Achieving this depends on a partnership between NASA and the European ExoMars project. Work was hoped to start this week on building the European orbiter, however it was announced yesterday that the mission is to be put on hold (again! Launch was initially planned for 2011 but may now not go ahead at all) as NASA cannot commit funds to its part of the project.
One of the main goals of the scientific study of Mars is to determine whether there is or ever has been life present. The first stage of the European ExoMars mission is to look for methane and other signs of life using an orbiter. The second stage is to use two rovers (one developed by NASA) to search the surface of the planet for evidence of past or present life. These will be lowered to the surface using a “skycrane” developed by NASA. The ultimate, long-term goal is collect and preserve exciting samples to be returned to Earth by a future mission.
The delay in the possibility of being able to return Martian samples to Earth is a big setback to the scientific study of the Red Planet. Sample return missions allow us to carry out a more extensive range of experiments and obtain more precise results than are possible with orbiters or rovers. This is because if all the equipment must be sent up with the mission there are constraints put on the capabilities of the instruments plus the experiments have to be carried out in a fixed amount of time. Returning samples to Earth also allows us to store samples for the future when technological advances could allow further experiments.
The first sample return mission was Apollo 11 in 1969. A total of 6 manned Apollo missions returned ~380 kg of moon rock. 3 Soviet missions also returned lunar soil. This material has been invaluable in contributing to our knowledge of the moon and continues to give us useful information to this day as scientific techniques and equipment develop.
The Genesis mission returned samples of the solar wind in 2004 allowing the most precise measurements of solar wind, and therefore the solar system composition, to be made. Measurements of N and O isotopic compositions (the highest priority of the mission) were published last week’s edition of Science magazine (24/06/11. Vol. 332 no. 6037). The Stardust mission collected samples from the comet Wild II in 2006 and the recent Hayabusa probe returned material from the asteroid Itokawa. All these missions have given us insights into our solar system we could not get from observations, meteorites and relayed data alone.
It would be a great blow for the future of planetary science if the ESA cannot achieve its ultimate aim of retrieving samples from Mars.