Bonjour Julien, thanks for your questions. I'll try to take each one in turn below.
julien.launay wrote:Is it always fixed? Is that astronauts can be removed to carry out an experiment?
There is one Astro Pi hard-mounted on a multi-use bracket in the Columbus module. A second one was mounted onto a hatch window in Node 2 but is now in storage. The crew can remove it from the bracket but constraints on crew time would mean that this activity would depend on them doing it in their free time
which cannot be guaranteed.
https://www.flickr.com/photos/timpeake/ ... 3026581031
julien.launay wrote:Do astronauts can use astropi when the proposed experiment. What time do they have to carry out the proposed experiments.
The Astro Pi will mainly be doing automated processing without the involvement of the crew. The crew time we do have allocated for Astro Pi is mainly for deployment and stowage activities. Despite this we have found the crew to be highly engaged in Astro Pi activities and willing to interact with student experiments, but this would depend on the personal choices of the crew member.
julien.launay wrote:What is the very exact positioning in the astropi iss. Ref for the compass, accelerometers, gyro. Reference 3 specific axes.
It lives in the starboard end-code of the Columbus module. The exact position can be seen in this picture: https://www.flickr.com/photos/timpeake/25225355364/
(look closely in front of Tim's nose). This resource explains the IMU sensor and which axes are which: https://www.raspberrypi.org/learning/as ... ovement.md
julien.launay wrote:What is the duration of a maximum experiences?
In previous missions we have let student code run for 7 days at a time, however this time around there will be code from every ESA member country. So I believe you will get one full day of run time in space so we can get through more programs in the time we have allocated.
julien.launay wrote:Which differences between the 2 raspberry? do they have the same sensors?
The sensors are not part of the Raspberry Pi computer, they reside on the Sense HAT which is an add on board. The Sense HATs on ground are identical to the ones in space. However the Raspberry Pi in space is a B+ so it may be that code you write on a Pi 2 or 3 might run slower on a B+. For a closer look at Raspberry Pi products go here: https://www.raspberrypi.org/products/
julien.launay wrote:could you confirm me that the cameras are out of work, we can't use them? If we can used them, could you tell me where are they pointing to?
No the cameras are working fine, they can be used for pictures and videos. However we have found that experiments for detecting radiation have not been successful because of the thick aluminium case. The camera points out of the bottom of the unit, it's located in the middle of the heat sink on the base. So usually the Astro Pi in Columbus will have it's camera pointing at the bulkhead.
I suggest you have a look at some of the previous science results here: https://astro-pi.org/competition/science-results/
There are links to the code they used and the data they received back from the ISS.
There is a slightly out of date FAQ on the Astro Pi website here too which may answer some of your other questions: https://astro-pi.org/coding-challenges/challenge-faqs/
I hope this helps.