iPad Screenshots


About the game

Tim Peake and other Principia Earth Observation Detectives all around the world need your help.
Astronauts and satellites orbiting the earth have taken lots of pictures, but we need to look at them carefully to find out more.
Each of our scientists has several missions to do, and you can help by:

Matching pairs of pictures – great for younger children!
Deciding if a picture was taken by a human or a machine
Working out what – or where – the pictures show
Finding details in the pictures.

Choose someone to help, choose a mission to help with and earn satellites for every mission you support.

You can have as many goes as you like at each mission: your best score will be kept until you have finished them all and decide to restart.

When you earn enough satellites, you become part of the Principia team.

About the app

The app is designed to allow children aged 5-11 to explore stunning images of the earth from space while thinking about the relationship between how features appear from this viewpoint and on the ground or on maps. Some of the games involve working things out, or depend on knowledge, but all can be played over and over again without time limits, so children can go away to find out more and improve their scores.

About the pictures

Some pictures were taken by ESA astronauts Tim Peake, Thomas Pesquet or their crewmates on ISS missions 46/47 and 50/51.

Others were created using data from Sentinel satellites that form part of ESA’s Copernicus programme, processed by Sentinel Hub from Sinergise.

Selection and additional processing was carried out by the EO Detective team at the Natural Environment Research Council’s National Centre for Earth Observation.


Bulb Studios
126.2 MB

Requires iOS 10.0 or later. Compatible with iPad.



Age Rating


  • Family Sharing

    Up to six family members will be able to use this app with Family Sharing enabled.

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