Principally aimed at PICLIST and Atmel list.

        Copied to Moon Project & Arocket

This may or may not be considered OT. A PIC or AVR or Z8 or .... may very
well feature in the final design. At the moment the choice is open.

I have a demanding design requirement (to put it mildly) which others may
be interested in commenting on and/or cooperating with. The project is
currently at the "lets think of as many factors as we can" stage. The more
wild/useful/interesting/tangential ideas the better.

An amateur group is planning to send a small rocket to the Moon. Timescale
is :within the next 5 years".
Various ideas are being investigated to attract sponsorship and/or in their
own right.

One proposal to be investigated is to place a small transmitter (no
receiver) on the Lunar surface with the object of transmitting a very short
occasional signal over as long a period as reasonably possible. The module
is currently envisaged as a sphere of about 500 grams mass with batteries,
transmitter, cpu and aerial deployment system contained within. Current
thinking is for this to be ejected immediately prior to impact to avoid
being trapped by the probe at impact. This will not reduce the final
velocity.

The transmitter is estimated to be in the 1 - 10 watt range with a transmit
time of around 1 second and a duty cycle of "TBD". Batteries will be "best
available" for the requirement. Antenna will be low (possibly as high as
unity :-)) gain. Carrying and deploying an aerial, batteries, transmitter,
cpu and impact protection system within the available mass budget is an
interesting challenge.

- Impact velocity of the payload is to be as small as possible but a soft
landing "as we know it" may quite possibly not happen :-).
The transmitter module should survive as high an impact velocity as
possible. Survival at velocities of up to 100 metres/second (200 miles an
hour)(!!) may be possible.
Much lower velocities are aimed for.

- Temperatures on the Lunar surface range from a high of about 400 kelvins
(130 C) to a low of about 100 kelvins (-170 C).
Attempted operation during most of the lunar night would probably be
inadvisable :-).
Operation at even peak temperature may be possible with appropriate design.
Batteries able to survive these extremes may be difficult to source :-)

These conditions are quite demanding by normal standards.
IF the module survives impact the biggest challenge is liable to be
surviving the lunar nights.
Previous lunar equipment has often failed to last more than 1 or 2 nights
(each night is around 2 weeks long).
Problems include both the absolute temperatures and thermal cycling.

QUESTIONS:

1.    Anyone interested even mildly please throw in as many even possibly
relevant ideas  - the more the better. Off or on list as seems appropriate

2.    Has anyone had practical (or theoretical) experience of very extreme
low temperature designs. (Not necessarily this low.)

3.    Is anyone interested in ongoing discussion about this project - off
or on list as appropriate.

I will introduce the Lunaris project per se at a later date - there is lots
for interested people to do.