I'm interested in working on an aspect of Lunar Mission One. In order to navigate from a trans lunar Injection orbit to a circular lunar orbit and eventual decent and landing, we'll need to precisely know our position relative to the moon.

Sun and star trackers are traditionally used for mid course positioning. Modern machine vision can use a view of the moon to determine the position of the spacecraft. This approach is currently being used by our closest peers the Astrobiotic lunar mission due to launch in the near future.

Right now I'd like to determine the requirements for this aspect of the design. From the hardware requirements of this system. To specifying a hardware in the loop testing environment for any systems under development. Do any members of the design team have any of these requirements already at hand or is everything still a work in progress?

At the Mission Control meeting yesterday (30th May at the Royal Institute, London) one of the participants suggested an ejectable beacon that could be deployed when approaching perigee during the landing site evaluation phase. This beacon could then provide a fixed reference already on the ground by which a more accutae determination of the landing site location could be traingulated. Perhaps we may need two or more beacons to make the accurate location possible. The locator beacons would have to survive dropping to the ground and operate long enough to allow the final landing manouvres to be completed.
Of course, being dropped even from the perigee point of a low-pass orbit at 2km/s to a dead stop on the ground might be a bit rough on a small device. Something to think about but, be aware of the need to keep mass as low as is practical for these things (similar considerations apply for the camera pod idea).

I was wondering if we could substitue a traditional electronic transponder with a non indigenous substance that could be measured by the existing scientific instrumentation on the lander module. This would remove the problem of a fragile transponder hitting the lunar surface and breaking.