Space Missions:
Missions (M1) - Current Missions
Missions (M2) - Communications / Navigation
Missions
(M1) - Current Missions
Session
chair: Dan
Showalter, CSA, Canada
Speakers:
Koji Takahashi and Tetsuo Yasaka , Kyushu
University, Japan
Microthruster Development and University Miniature-Satellite
Program in Japan
Abstract:
Micro satellite is an attractive topic in both of space science and space
education. The short period and low cost for its development are major
advantages for university educational programs. There are several projects
of micro satellites in Japanese universities, including CanSats of the
ARLISS group. The piggyback satellites using H2A is also under consideration
and a new organization named UNISEC (University Space Engineering Consortium)
is recently founded in order to support the hand-made space projects of
university students. On the other hand, the biggest impact on science
side is the multi-point measurement mission of space environment using
formation flight by hundreds of micro satellites. The microthruster is
a key for this kind of future mission and several kinds of microthrusters
are under development in Japan. MEMS technology is applied by Tohoku University
and Kyushu University to build micro solid rocket arrays and liquid monopropellant
microthrusters. Both of them are still far from practical application
while micro pulsed plasma thrusters (PPTs) are studied by TMIT, University
of Tokyo and so on. Micro PPT using solid propellant has simple structure
and suits for miniaturization but the large impulse of chemical thrusters
are preferred for quick motion, for example, at the last stage of micro
satellite mission to put itself out of the orbit preventing the debris
problem. The present state of microthruster development in Japan is reviewed
and the problems that we are confronted with are discussed.
Zhonghe
Jin, Zhejiang University, China
Design of the MEMS-Pico Satellite
Abstract:
The development of the integrated circuits (IC's) and micro-electro-mechanic
system (MEMS) makes it possible to fabricate satellite smaller and smaller.
Now it is possible to fabricate satellite with weight less than 1kg, i.e.
pico-satellite. Possible applications of such small satellite include
distributed sense, scientific experiment, and test small devices intending
to use in space. For universities, development of such small satellites
also provides chances for students hand-on opportunities in an acceptable
cost.
A pico-satellite named "MEMS-Pico" is being developed in China.
This work is a joint program between Zhejiang University and Shanghai
Institute of Microsystem and Information Technology, Chinese Academy of
Sciences. The original propose of this satellite is to provide a testbed
in near-earth space for MEMS devices, such as accelerometer, micro-gyros
and infrared sensors, being developed in China.
MEMS-Pico is designed as a tumbling satellite with neither attitude control
nor propulsion. It consists of no moving parts, only solid-state electronics
and the structure. Figure 1. is the photograph of the satellite on the
test equipment. The MEMS-Pico is a 26-face object, with 18 square faces
and 8 triangle faces. 17 squares are covered by solar cells, with total
size of 270cm2. The solar cells are expect to provide 2W of electrical
power in orbit.
Payload of the MEMS-Pico includes a MEMS infrared sensor and a CMOS camera.
However, the most important part of the spacecraft is probably the communication
transceiver. The transceiver works on S band, with uplink at 2100MHz and
downlink at 2300MHz. The downlink rate is 4096 bits per second with QPSK
modulation on the carrier. Since there is above 200MHz difference between
the frequency of downlink and uplink, 2 different sets of antenna are
used for downlink and uplink, respectively. Each set of antennae composed
of 2 antennae installed on two reverse triangle faces of the MEMS-Pico.
So that each set of the antennae equivalents to an omni antenna. This
design makes it possible to receive signal even the spacecraft in a random
attitude or in tumbling. Figure 2 shows the pattern of a set of the antennae.
Laurent
Marchand, ESA, Europe
MNT Based Missions an ESA Perspective
Missions (M2) - Communications
/ Navigation
Session
chair: George
Akhras, RMC, Canada, Guilio Manzoni,
Mechatronic GmbH, Austria
Speakers:
Gerald
Falbel, Optical Energy Technologies, USA
Attitude Control and Solar Power for Pico,
Nano, and Microsatellites
Abstract:
This paper describes available technology for attitude sensing, control
and solar power for low cost, low weight pico, nano, and micro-satellites.
The weight ranges for these satellites run from 1 Kgram to 100 Kgrams
At the low end of the weight range is the CUBESAT spacecraft series, a concept developed by Professor Robert Twiggs of Stanford University, and applied by Professor Jordi Puig-Suari of California Polytechnic State University (CALPOLY), San Luis Obispo CA. The CUBESAT satellites are a series of 1.0 Kgram. free flying spacecraft used for university student space experiments, and are launched from "piggy back" opportunities on other space missions. The paper describes a <50 gram two axis ±0.5° accuracy sun sensor, and a concentrator solar panel, which can provide a "Figure of Merit of> 150 watts/Kgram using the latest 26% efficiency, triple junction solar cells.
A system is described which will be flight tested on the CALPOLY CUBESAT in the spring of 2003 incorporating the sun sensor, the solar panel and attitude torquing coils, which will flight test the sub systems which can provide either spin stabilization on the sun line or 2 or 3 axis stabilization for the 1.0 Kgram spacecraft.
For larger weight spacecraft, other subsystems are described, including low weight/cost fully developed, 2-axis gyros, which, when combined with the sun sensor, a <50 gram static earth sensor, and algorithms in the spacecraft computer, allow 2 and 3 axis sun or earth stabilized attitude control.
Finally, in the next level of sophistication, MEMS-fabricated reaction/flywheels with magnetic suspension, developed by Honeywell Technology Center can be incorporated into satellites in the 1.0 to 100 Kgram weight range. These "Micro-wheels" provide the combined capability of acting as attitude control reaction wheels, and energy storage mechanical batteries, for 2 and 3 axis attitude stabilization systems.
Olivier
Vendier, Alcatel Space Industries, Europe
RF MEMS Use Within Space Telecom Payload
Abstract:
It is expected than the advantage of MEMS technologies, demonstrated already
in areas such as automotive, medicine, etc… will also benefit space
applications. A bright future can certainly be predicted for MEMS aboard
space-borne payload, following the same route than MMIC experienced 15
years ago. In the field of RF MEMS, the main advantages offered by
these technologies are mainly associated with the less-dB and higher-Q
trends. However, big and fundamental issues have to be resolved. Priority
must be given to reliability and packaging, and this constitutes very
exciting challenges for space engineers and scientists. For Alcatel Space,
actions are on-going - in collaboration with European labs and companies
- through internal studies and different contracts from European Community,
French Minister of Industries and agencies (ESA, CNES)
Guerman
Pasmanik, Passat, Canada
Adaptive Transmission of Eyesafe laser Emission
from Minisatellite to Ground Vehicles
Abstract
Microsystems today are still in the growing phase
: from the concept of the smart sensor developed in the early 80's to
the feasibility of very small integrated systems reached in the 90's,
research and development activities are in a constant progression. After
an euphoric phase started in 1995, MEMS are starting to be present in
all commercial sectors :automotive, computer systems, telecommunication,
biomedical… and space. However, in terms of market penetration the
situation is not so clear : there are few MEMS in commercial off the shell
products, many prototypes in laboratories and huge investments !
This situation is a new one for the space industry. In fact, space products
need to be well stabilized especially concerning technologies for innovative
systems. But for Microsystems, agencies and main contractors seen to have
decided to take the way of innovation : the microsmall world must be megabeautiful
!
From a reliability point of view this situation is
also a new one. In the past, the working scheme for an engineer in the
quality domain (reliability, failure analysis, technological analysis…)
was :
- Well known and qualified products (SCC standard for example). In this case, quality assurance activities consist of performing evaluation, qualification and maintenance of qualification,
- COTS : electronic components mass produced for commercial applications. Technological activities for COTS are more focussed on markets and technology surveys,
- Dedicated products or components only produced
for space activities (optical detectors for example). There is
a strong link between agencies and foundries that help quality assurance activities.
MEMS quality assurance cannot be included in one of these schemes mainly because mass production only deals with products generally not useful for space systems (e.g. inkjet parts, hard disk heads …) and mass volume foundries are not " open" to small customers.
The failure and technology analysis lab of the CNES
has proposed a new approach based on a tight relationship between conception
activities, missions needs and micro characterization of technologies
and materials. Due to multiple technologies potentially useful for MEMS,
the main challenge is to get technology data concerning reliability in
parallel with the product development. To perform the collection of this
data, test vehicles are designed to
identify potential weaknesses in the final product as soon as possible.
An example of this method applied to a microswitch will be presented.
However collecting data on the technology and on the
design through test vehicles is not sufficient to evaluate and then to
qualify a product : understanding the failure mechanisms is mandatory
for test definition. In fact each test level used for the product evaluation
must be defined in accordance with the potential failure mechanisms. This
is the corner stone of a good lot screening. MEMS can not only be considered
as components : they are real systems and a system level approach must
be developed. Examples of designs for testability, fault injection techniques
and virtual design concepts will be presented.
Last update - May 28, 2003
