AMS Satellite Platform

1
AMS Satellite Platform

• Conclusions of discussions at CAST
• Beijing, November, 2005
• Joseph Burger, MIT

Comments/Status as per Jan 5th, 2006 are included
in yellow boxes (M. Molina)
2
AMS with superconducting magnet is too heavy to
be launched into a sun-synchronous orbit with a
CZ-3B rocket. The heaviest payload possible is
7.3 T. AMS without USS weighs 5.9T and the
platform weighs 1.5T, leaving less than nothing
for AMS to platform interface.
3
Other orbits are possible. Launch directions
from Shichuan are limited by the need of passing
over relatively unpopulated areas. The best
possibilities are for an orbit inclination of 50
degrees (similar to ISS orbit), and 28.5 degrees.
The max. launch weights are 8.35 and 9 T,
respectively. The 28.5 degree orbit doesn't pass
over enough Chinese ground stations to download
satellite data, but might be usable if we can use
other (possibly NASA or ESA) ground stations.
Both of these orbits will require heavier
batteries and solar arrays than the sun
synchronous orbit, but we estimate we have at
least 0.7T available for the AMS to platform
interface.
MM- Jan 2006 For a 31 orbit a launch
capability of 8300 Kg is reported by
CAST. However, 31 inclination are not acceptable
from the physics point of view, because of the
too large rejection of low energy particles. A
51 orbit should be studied, instead.
4
CAST would design platform with enough fuel to
do attitude control and reboost to 500 km
altitude for at least 3 years. If uncorrected,
the altitude would drop to 460 km after 1 year,
380 km after 2 years, and 260 km after 3 years.
Below 300 km attitude control may not be possible.
5
We have said we need 2617W peak (in AMS
terminology) or "operate (in CAST terminology),
and that AMS can take all this at 28V and do its
own conversions to other voltages needed. PDS
consumption of 333W disappears, but we will need
a smaller PDS equivalent to do some things like
operate cryocoolers. We will change most heaters
to operate at 28V to minimize power conversion
losses.
6
We have given AMS weight as present 6891 kg minus
the weight of the USS and ISS mounting hardware
(727KG 268 KG 995 kg) or 5896 kg
MM- Jan 2006 Updated number by A. Kounine is
5837 Kg which includes all AMS subsystems and 90
Kg contingency. NO support structure weight
included.
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The vacuum case should be supported similarly to
the way it is in the NASA USS. R. Becker has made
some draft proposals using vertical beams
attached to these points. Some method such
as cross braces are needed to distribute forces
from these supports to the cylindrical platform
structure. Modifications have to be made to the
lower USS to Something more suitable. CAST and
AMS will work together in designing
this interface structure
MM- Jan 2006 New layout drawn by R. Becker (See
next pages pictures)
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MM- Jan 2006 New picture, CAD model on cern ftp
site
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MM- Jan 2006 New picture, CAD model on cern ftp
site
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MM- Jan 2006 New picture, CAD model on cern ftp
site
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MM- Jan 2006 New picture, CAD model on cern ftp
site
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For data exchange, Zhang Guobin has a CERN e-mail
address and is CAST contact person. CAST will
arrange a method of exchanging data through ftp,
probably the CGS ftp site.
MM- Jan 2006 Email address used is CERNs Ding
Xiaobo. ftp data exchanging is still TBD
13
Launch and test loads for the CZ-3B rocket are
available, but only for lighter payloads
than AMS. Chen Min Kang from CALT has been given
an approximate mass and c.g. for the AMS
satellite and will have a better
(still Preliminary) estimate of these loads
calculated.
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The FEMs of the CAST platform and AMS must be
combined for a detailed design. This will
take some time. To start, simplified load
factors, like the ones we got from NASA are
needed. CALT does not use this system, but the
NASA values seem to be close enough to start
with.
15
MIT should obtain the vacuum case FEM and the
combined AMS detector FEM compiled by B. Sommer,
and provide these to CAST. CAST is providing R.
Becker with the platform FEM, and CALT is
providing copies of its launcher user manual (so
far in Chinese an older English version is
available) and a document giving requirements on
the FEM for coupled load analysis.
MM- Jan 2005 FEM reduced model of AMS will be
provided by NASA Monday Jan/9/2006 in .op4 format
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The AMS structural test article is needed and MIT
should obtain it from NASA. CAST proposes having
a complete STM of platform and payload.
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The fairing has 3.85m i.d. 5m height. The outline
is in the launcher user manual. R. Becker says
the current radiators and crates would fit inside
if they are moved 153mm closer to the magnet.
This precludes changing a few electronics cards
in place.
MM- Jan 2006 WARNING the fairing diameter
quoted in HanBo presentation is the OUTER
diameter. 3.85 m is the dynamic envelope for
AMSS. WARNINGHeight is less than 5 m in the area
where ID is 3.85 New accomodation by R. Becker is
based on main radiators splitted in two halves,
vertically
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We are still trying to find a good solution
for the layout of the radiators and solar
panels and the orbit attitude control to get
good thermal control and power availability
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The ground support equipment for installation of
the AMS to platform interface, transport to China
and integration at the launch site has to be
designed and built.
20
Responsibilities for redesign of AMS TCS in the
case of satellite have to be settled between 1.
CAST 2. SDU 3. CGS
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Requirement for magnetic torquers Satellite
dipole moment lt 10 Am2 in case of 3 torquers of
100 Am2 dipole moment CAST needs an estimate of
AMS dipole moment. Does the platform have
any components which are affected by a magnetic
field? AMS will supply a field map.
MM- Jan 2006 Latest estimate for AMS dipole
moment is lower than 27200 Am2, and is being
measured by SCL number will be delivered at TIM
(CERN) Jan 31st, 2006
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