Progress report 16th. March 2003

 

 

Foremost during the last 4 months has been the critical question of Tray number four SFS – “This Space For Science

A number of ideas have been put forward and we are now firming up on just two. The first a simple ozone measurement system and the second - which is rapidly gaining ground as the primary experiment – an attempt at some active Attitude Determination and Control (ADAC). It’s proposed to try control of the satellite using the geomagnetic field.

To carry out this experiment it will be necessary to fly a number of sensors and these are in course of production. Some will be specially constructed while some will be commercially available items adapted for use such as locally made small, relatively inexpensive 3-axis magnetometers, and suitable GPS equipment available off the shelf to be acquired as funds become available. For other items such as Sun and Earth sensors it has been decided to build from scratch and we greatly appreciate the AO-40 sun sensor team – and in particular Alan Bloom (N1AL) who found a spare PCB. This we have now populated, and we will be using this as a trial / demonstrator unit from which to develop a compact version to fit into a small ‘attic’ extension similar to that fitted to AO-18 (Webersat).

Also into the extension will be a Webersat style earth / horizon sensor, which will be fitted with two pairs of photocells - one pair in the visible, and the other in the near infrared spectrum. In accordance with the lessons learnt on Webersat (see proceedings of the AMSAT-NA 1993 Space Symposium) the internals of the earth sensor have been carefully machined to avoid the reflections noted in the original.

 

 

 

On the basis that “a picture is worth a thousand words” a simple B/W CCD camera is also under consideration similar to the YACE unit on AO-40.  It will be used as a ‘confidence check’ should we be in any doubt about the results from the other sensor readings!  There are no plans for detailed earth imaging.

 

 

 

 

With the fitted sensors it’s hoped that with appropriate software we can pulse a 3 axis magnetorquer and get some meaningful control of KiwiSat - indeed perhaps pave the way to a full attitude control system that would enable folded solar cell panels to be used to increase the power budget of future MicroSats. From both a thermal and a power availability point of view these first efforts at active ADAC will be limited.  But at least it’s a start.

If we are able to determine the satellites attitude and direction accurately a simple plot of some areas of the ozone layer using the ozone sensor may then be possible.  All the appropriate software to view the results will be made available as it is produced and proven.

With an active ADAC system which will include a magnetometer, it will not be possible to fly the normal bar magnets on KiwiSat, but removing these and allowing the satellite to become a ‘tumbler’ when the ADAC experiments are completed will not affect the communication prospects.  The antenna patterns provide for good all-round communication directivity according to the antenna modelling that’s been completed.

General activity on the satellites other systems has also been advanced over the past months.  Hans Holtz (ZL1HB) – whom we welcome to the team - is well advanced on the Battery Charge Regulator.  Han’s expects to have the first prototype board up and running in about 2 months by which time a suitable battery pack – NiCd’s at first – will be assembled and ready for some trials.  Unfortunately we still have not located a source of high quality/efficiency solar cell pieces so his trials will involve a mock-up power source. (If you know of a supplier of small quantity GaAs or triple junction cell pieces please contact a member of the committee.)

Work on the RF side is progressing but Terry Osborne (ZL2BAC) has been filling the breach to get some activity underway on the computer.  As luck would have it Lyle Johnson (KK7P) will be in New Zealand in April and we are hoping to tap his very wide knowledge and experience of AMSAT computing. Lyle’s very kind offer to help and advise was grabbed with both hands!

So, work progresses and a number of items reflecting that activity have been added to the photo gallery.  Please note that we still need more help and in particular it would be great to have someone to take charge of the computer hardware and relieve Terry ‘2BAC of that burden.  A lot of work has already been done so whoever takes it on will be at least a few rungs up the ladder. On the software side we have a number of systems already catered for but some really imaginative work will be needed to pull together the planned systems. Again if you do have the skills and would like to get involved please let us know.

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Last updated 16/03/2003