The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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On 29 December 2013, ESA’s Mars Express will make the closest flyby yet of the Red Planet’s moon Phobos, skimming past only 45 km above its surface.
As the spacecraft passes close to Phobos, it will be pulled slightly off course by the moon’s gravity, by a few tens of centimetres. This small deviation will be measured using the spacecraft’s radio signals, and then translated into measurements of gravity, mass and density at different locations on the moon.
This animation shows how the flyby would appear from a vantage point near Mars Express, with Phobos passing by beneath. The relative movement between the spacecraft and moon has been speeded up ten times faster than actual.