1 Preface
For developing space remote sensor with
high quality, apart from solving various
theoretical questions of remote sensor itself,
it is necessary to solve the problems of
ground test and environmental experiment for
remote sensor at the same time to ensure high
quality and high reliability. No one of the two
points can be neglected. This paper describes
some aspects about Dynamic Environment
Testing System for space remote sensor
developed by Beijing Institute of Space
Machine and Electricity under Chinese
Academy of Space Technology.
2 Necessity of developing Dynamic
Environment Testing System (DETS)
For space remote sensor manufacturing,
fitting, adjusting, and testing, all the activities
are being done in the ground surface under
the environmental condition of standard
atmosphere pressure. All factors such as
continuous convention and fluttering of the
air around the working site upon the effect of
heat (temperature field), and various kinds of
disturbances imposed by people, ground
vibration, gravity field etc., will deface the
performance of sensor to a considerable
extent. However, when remote sensor
traveling in space, the around environment is
at high vacuum (or low air pressure of the
payload bay of satellite), weightlessness, no
artificial disturbances and no ground
vibration etc., but the factors of solar
radiation and cosmic rays etc. are existed.
Because of the difference between the two
environmental conditions, the functional
performances of remote sensors are very
different in space and in ground surface.
Obviously, the most concern of us is the
functional performance of the remote sensor
in space orbit. Generally speaking, under the
environmental condition of satellite orbit, the
performance of remote sensor will decline by
30%or more, comparing to that of in ground
test and measurement. Along with enlarging
of focus length and optical aperture, and
increasing of resolution, these affections will
show up more obviously. Hence, through a
certain ground experiments, to find out
factors influencing the performances of the
sensor and the degree of effectiveness,
becomes special concern of designer.
Building Dynamic Environment Testing
System is important means to solve this topic.
The DTES is a large integral ground testing
equipment. It is used to simulate satellite
orbital environment, and to provide real-time
testing conditions for remote sensor working
under such conditions. In the period of
engineering model development, remote
sensor systems will be taken in an integrated
environmental experiment to
comprehensively check the functional
performances of optics, mechanics,
electronics, and heat subsystems, so that the
real performances of the remote sensor in
orbit can be estimated in advance. The
significance of these experiments, first of all,
in the period of engineering model
manufacturing, is to discover existent faults
of the sensor itself early, concluding the
problems in designing, manufacturing, fitting
and adjusting etc., so as to correct them in
time, and secondly, to return experimental
result back to the designers, so as to redesign
the remote sensor system and to adjust
relevant parameters to have a good match to
improve the performance of redesigned
system. As saying above, the performances of
the remote sensor in orbit will fall by 30% or
more, comparing to that of in ground testing.
However, after such experiment and
adjustment, the functional performance will
recover by 15% or more.
The DETS developed by our country for
space optical remote sensor environment
experiment can fulfill experimental needs of
optical remote sensor of all kinds. During the
time of engineering development, by
absorbing successful experiences of similar
systems in domestic, and adopting the merits
of similar systems abroad, combining the two
factors with the practice of China, we decided
the overall schemes of the DTES. The
emphasis is to fulfill the needs of optical
remote sensor testing, and the needs of other
experiments which need vacuum cold and
dark environment are also considered to a
certain extent.
3 Composition of Dynamic Environment
Testing System
The DTES is composed of three subsystems,
Thermal Vacuum Simulator (TVS), Optical
Testing System (OTS) and Micro-Vibration
Isolation System (MVIS). The DTES is about
23m in full length, 13m in height (7m above
ground, and 6m underground). The principal
part of the system is mounted in a big hall
with area about 700m
2. The environmental
conditions in the hall about temperature
(22±1)
°C, humidity (50±10)%, air purity 100
thousand degree. Clearance height of the hall
is 12m. There are optical and electronic
testing instrument room, mechanical fitting
work place, 5T crane, and a variety of
laboratory equipment, to fulfill the needs of
experiments. There exists an auxiliary room
near the hall, with the auxiliary facilities in it.
In a word, the distinguishing feature of the
DETS is that it is an integration of optical,
mechanical, electrical, and thermal
subsystems, vibration-isolation, clean,
pollution-free, and large scale, and it is only
one in domestic, special for space remote
sensor environmental experiment.
The outlines of the three subsystems are in
below.
3.1 Thermal Vacuum Simulator (TVS)
TVS is used to imitate vacuum or lower
atmosphere pressure, cold and heat
environment in satellite orbit. It consists of a
q4m*8.2m vacuum tank plus various
auxiliary devices and instruments. The
efficient working space of the tank is
q3.4m*6m. It can form a 6*10
-6
P
a extreme
vacuum (non-load) and
£100k cold and dark
environment. Vacuum degree and
temperature field are adjustable according to
needs. Specially in the time of optical remote
sensor experiment, the temperature around
the sensor can be continuously adjusted at the
range of -20
°C ~ +50
°C, with the non-uniform
of the temperature field
£±0.3
°C,
the stability of the temperature field
£0.5
°C/24h. The vacuum volatilization
organic pollution
£1*10
-7g/cm
2 strictly
ensures the optical system out of pollution.
Hence, the performance of TVS is on the
leading position in similar domestic apparatus.
Three-dimensional adjustable platform in
vacuum tank is used for adjusting the attitude
of the experiment object mounted on it to
match the optical system being checked. All
in all, the TVS has enough experimental
space, good vacuum condition, clean and neat
environment with high or low temperature, to
fulfill the needs of every kind of remote
sensor experiment.
