Progress report 28 September 2004
Progress since the last report has been slow in
some areas but it's fair to say that things are moving a pace at the moment. In
no particular order, here is where we are:
"This Space for Science"
With the ideas for this reduced to two at the last report a more
detailed look was undertaken at the final contenders. They are a simple ozone
experiment and an active Attitude Determination and Control for the spacecraft.
Of the two it was obvious that the former was very much dependent on the latter
and the major effort and resources - both manpower and financial - have been
concentrated on the systems and equipment necessary to support the ADAC aspect.
As a result, a considerable amount of work has been undertaken to improve and
develop the basic systems covered previously and we have now extensively tested
the final designs for the Earth/Horizon sensor and the Sun
Sensor. Both have been produced using home brew PCB's using 'through hole' technology
which - with its 'wide open spaces' - allowed us to make any modifications with
reasonable ease. Happily none was required and both boards are 'as etched'.
Now well proven, the schematics are currently being
converted into the necessary SMT artwork and it is intended that both systems
will be incorporated on one board to reduce the component count. The variable
resistors will be "installed" on a system of pads that will support their
replacement by fixed resistors once the sensitivity levels have been set.
In tandem with work on the electronics, it was decided to revisit the sun sensor
head with a view to reducing its size and weight. The reworked heads - two will
be flown - are complete and tested and a saving of over 50% on size and weight
has been made.
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Well worth the effort when looking at launch costs of around
US$10 /gm!
A 3 axis Honeywell magnetometer head has been acquired and in keeping with the
policy of "mock up and try" whenever possible, a graduated gimbal fitting has
been produced to enable the unit to be 'worked' as far as practical in an earth
bound environment. Only the 25mm x 18mm PCB - located in the centre of the
picture - will fly. (!!)
As previously mentioned it's hoped to include a GPS receiver. This will be
coupled into the L band Rx antennas. Unfortunately, a suitable unit - at a price
we can afford - is proving elusive. As some will know, the 'standard' GPS, now
very cheaply available over the counter, is only accurate at speeds up to
(approx) 2000mph and at altitudes below 60,000ft.
With KiwiSAT travelling at
18,000mph and in orbit at an altitude of 500 miles, a 'standard' unit falls
somewhat short of the mark!
The bottom line is that we can't afford a 'high speed' version at the present
but things may change and to keep our options open we are making allowance for
GPS in the satellite. In the absence of the required version a 'standard' GPS
board is down to fly. It's understood that the positional data from this will be
of no value but we need an accurate clock on board and the 'terrestrial' version
will give us a very acceptable timekeeper if nothing else. A suitable board is
currently to hand and this has been fitted with a screening box with a view to
integration of it - or a suitable replacement - into the final layout.As can be seen, considerable work has been done on the ADAC aspect. That does
not mean that the ozone experiment has been abandoned - it's still there but on
the 'back burner' for the time being.
RF Systems.
Initially one of the slower systems, large strides have been made
during the past few months.With little to show a year ago it was decided to convert commercial Tx and Rx
boards and - with a suitable keyer - to make up a cross band repeater for use
(initially) in the Auckland area. It was felt that this would put the project on
the map and it would also serve a dual purpose. It would be installed and run
from the vacuum chamber loaned by Massey University in its Albany Campus on
which the temperature cycling facility needed to be set to work. For added
realism the antennas to be used would be those on the test module set up by
Terry (ZL2BAC). As it turned out other work prevented much activity on the
thermal side but the RF trial proved successful. The two experimental units -
supplied by Salcom Ltd. - and engineered into the repeater by Kelvin (ZL3KB) was
on the air for several months as ZL6SAT.
Not ideally situated in Albany as the
district is very much in a low lying 'bowl' the unit was, however, worked by
many local stations and was finally shut down in June when the lessons learned
enabled work on a flight-qualified unit to be taken in hand by Kelvin. That is
progressing well and the Tx flight design has been bread-boarded. It delivers
either 1 or 2 Watts with good efficiency and it's worthy of note that lengthy
research was necessary to identify materials and then rework the coil formers
using space worthy plastic material. (Space materials again…!) The PCB artwork
is with a board manufacturer and mid October should see the first
flight/engineering board up and running.
Work on the U/V transponder is currently shelved whilst attention is diverted to
the design and build of a transponder unit for Phase 3E (Express) in support of
AMSAT-DL. There are clearly significant differences between the U/V transponder
for P3E and that for KiwiSAT but there will certainly be some spin off between
the two and AMSAT-ZL is delighted to be given the opportunity to contribute to
the '3E project. We will certainly learn a lot from the experience and the
inevitable delay to the RF aspect of KiwiSAT will be well worth it in the long
run. The transponder effort will not have any major affect on the other systems
of course. Work on them goes on.
IHU Computer
Of all systems to take a leap forward over the past year, the IHU is
the 'cherry on the cake'!
Lyle Johnson (KK7P) visited us earlier in the year and by the time he left we
had the makings of our IHU. Many thanks, Lyle! We have now - with his continued
help and that of Chuck Green (N0ADI) - got to the stage where we are have the
artwork ready to produce the necessary 4 layer PCB's. Our thanks to professional
PCB designers Hans, Simon, Nick, and Kevin from various New Zealand electronics
companies for their sterling support.
We are investigating the supply of components for four sets of IHU boards. These
will be used for development with one reserved for eventual flight. With the
computer hardware finalized the detailed work on the software is also firming up
and Daniel (ZL1DFA) - who is leading our software team - has many far-reaching
plans that can now come into their own. A most productive and encouraging few
months.
Power
The decision has been made to use high efficiency (28%) solar cells
and we are currently looking at ways of financing their acquisition. The use of
a lesser efficient and very much cheaper cell was not seen as cost effective and
despite the small numbers in AMSAT -ZL and the mammoth problem of raising the
necessary funds, the challenge will be taken up.
From a battery point of view NZART Branch 12 (Hamilton) have volunteered to help
with the battery choice and selection/matching task. We welcome Robin (ZL1IC)
and his team on board and look forward to their input. It's always great to have
fresh minds and support in any area and particularly so on the battery side. The
failure of storage batteries has provided the final curtain for many if not all
amateur satellites. They need to be right! Branch 12's offered involvement is a
great boost.
In the meantime access to the Battery Analyser and other facilities provided by
Massey University will be used to complete the 'familiarisation' work currently
under way on both NiCd and NiMH cells. Hopefully a chemistry selection will be
firm by the end of the year and a main and standby pack will be well in course
of preparation. The basis of the Battery Charge Regulator has been well
established by Hans (ZL1HB) and the detailed work will no doubt pick up when the
battery pack parameters have been finalised.
Structure
The decision to use the high efficiency solar cells presents one
immediate problem; they come in larger 'pieces'! Unfortunately a change is now
needed to the existing solar panel outline and this has necessitated a small
change to the overall size of the satellite. In addition to this modification
the AMSAT-ZL proposal to plan for a Russian Dnepr launch means that the original
release system - which was based on the 'sprung release' of the original
MicroSats - will not now be suitable. Changes to meet the 'drop off' launch
system that the reversing third stage of the Dnepr launch vehicle employs, must
be made. Adding to the above, an offer by Mike Jack of Stanier Engineering to
CNC machine the trays from solid aircraft alloy was too good to miss and this
again adds a new perspective to the design. We are grateful to Mike for his
offer and can confirm that all these design changes are being worked through. As
a result, Fred's limited CAD experience is being extended and consolidated in
the process; but no bad thing that! Work on the re-design will continue
throughout the year.
General
Fred attended and much enjoyed the 2003 AMSAT-UK Colloquium and spoke
on the KiwiSAT Project. This appeared to go down well with those attending and
he subsequently made contact with several people who offered help and advice on
several areas of the build. All extremely useful as we get into the real meat of
the project. AMSAT-ZL was not represented at 'Surrey' this year but it's on the
cards that perhaps two will be there for the 2005 event expected next July.
Material and processes to meet the very demanding conditions in a space
environment remain a problem but access to the appropriate web sites has become
easier during the past year. We can now at least identify - if not readily
obtain in small quantities - the materials appropriate to the job! That problem
is going to remain with us here in New Zealand and we would be delighted to hear
from anyone, anywhere, that can help source "small quantity" space qualified
materials.
Fund raising is still very much an issue of course, as is the need for more
volunteers. Any input on either is very welcome and you will find a ready
listener in any of the members of the AMSAT-ZL committee! The pace is increasing
but it's never too late to join and work with the team.
Give it a go - you'll enjoy it!
Last updated 02/10/2004