ASTM E491-73(2004)e1
(Practice)Standard Practice for Solar Simulation for Thermal Balance Testing of Spacecraft
Standard Practice for Solar Simulation for Thermal Balance Testing of Spacecraft
ABSTRACT
This practice provides guidance for making adequate thermal balance tests of spacecraft and components where solar simulation has been determined to be the applicable method. Careful adherence to this practice should ensure the adequate simulation of the radiation environment of space for thermal tests of space vehicles. This practice also provides the proper test environment for systems-integration tests of space vehicles. However, there is no discussion herein of the extensive electronic equipment and procedures required to support such tests. This practice does not apply to or provide incomplete coverage of the following types of tests: launch phase or atmospheric reentry of space vehicles; landers on planet surfaces; degradation of thermal coatings; increased friction in space of mechanical devices, sometimes called "cold welding"; sun sensors; man in space; energy conversion devices; and tests of components for leaks, outgassing, radiation damage, or bulk thermal properties.
SCOPE
1.1 Purpose
1.1.1 The primary purpose of this practice is to provide guidance for making adequate thermal balance tests of spacecraft and components where solar simulation has been determined to be the applicable method. Careful adherence to this practice should ensure the adequate simulation of the radiation environment of space for thermal tests of space vehicles.
1.1.2 A corollary purpose is to provide the proper test environment for systems-integration tests of space vehicles. An accurate space-simulation test for thermal balance generally will provide a good environment for operating all electrical and mechanical systems in their various mission modes to determine interferences within the complete system. Although adherence to this practice will provide the correct thermal environment for this type of test, there is no discussion of the extensive electronic equipment and procedures required to support systems-integration testing.
1.2 NonapplicabilityThis practice does not apply to or provide incomplete coverage of the following types of tests:
1.2.1 Launch phase or atmospheric reentry of space vehicles,
1.2.2 Landers on planet surfaces,
1.2.3 Degradation of thermal coatings,
1.2.4 Increased friction in space of mechanical devices, sometimes called "cold welding,"
1.2.5 Sun sensors,
1.2.6 Man in space,
1.2.7 Energy conversion devices, and
1.2.8 Tests of components for leaks, outgassing, radiation damage, or bulk thermal properties.
1.3 Range of Application
1.3.1 The extreme diversification of space-craft, design philosophies, and analytical effort makes the preparation of a brief, concise document impossible. Because of this, various spacecraft parameters are classified and related to the important characteristic of space simulators in a chart in .
1.3.2 The ultimate result of the thermal balance test is to prove the thermal design to the satisfaction of the thermal designers. Flexibility must be provided to them to trade off additional analytical effort for simulator shortcomings. The combination of a comprehensive thermal-analytical model, modern computers, and a competent team of analysts greatly reduces the requirements for accuracy of space simulation.
1.4 UtilityThis practice will be useful during space vehicle test phases from the development through flight acceptance test. It should provide guidance for space simulation testing early in the design phase of thermal control models of subsystems and spacecraft. Flight spacecraft frequently are tested before launch. Occasionally, tests are made in a space chamber after a sister spacecraft is launched as an aid in analyzing anomalies that occur in space.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
´1
Designation: E491 – 73 (Reapproved 2004)
Standard Practice for
Solar Simulation for Thermal Balance Testing of Spacecraft
This standard is issued under the fixed designation E491; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
´ NOTE—An editorial change was made in paragraph 6.6.5.2 in February 2005.
1. Scope brief, concise document impossible. Because of this, various
spacecraftparametersareclassifiedandrelatedtotheimportant
1.1 Purpose:
characteristic of space simulators in a chart in 7.6.
1.1.1 The primary purpose of this practice is to provide
1.3.2 The ultimate result of the thermal balance test is to
guidance for making adequate thermal balance tests of space-
prove the thermal design to the satisfaction of the thermal
craft and components where solar simulation has been deter-
designers. Flexibility must be provided to them to trade off
mined to be the applicable method. Careful adherence to this
additional analytical effort for simulator shortcomings. The
practice should ensure the adequate simulation of the radiation
combination of a comprehensive thermal-analytical model,
environment of space for thermal tests of space vehicles.
modern computers, and a competent team of analysts greatly
1.1.2 A corollary purpose is to provide the proper test
reduces the requirements for accuracy of space simulation.
environmentforsystems-integrationtestsofspacevehicles.An
1.4 Utility—This practice will be useful during space ve-
accurate space-simulation test for thermal balance generally
hicle test phases from the development through flight accep-
willprovideagoodenvironmentforoperatingallelectricaland
tance test. It should provide guidance for space simulation
mechanical systems in their various mission modes to deter-
testing early in the design phase of thermal control models of
mine interferences within the complete system. Although
subsystems and spacecraft. Flight spacecraft frequently are
adherence to this practice will provide the correct thermal
tested before launch. Occasionally, tests are made in a space
environment for this type of test, there is no discussion of the
chamber after a sister spacecraft is launched as an aid in
extensive electronic equipment and procedures required to
analyzing anomalies that occur in space.
support systems-integration testing.
1.5 This standard does not purport to address all of the
1.2 Nonapplicability—This practice does not apply to or
safety concerns, if any, associated with its use. It is the
provide incomplete coverage of the following types of tests:
responsibility of the user of this standard to establish appro-
1.2.1 Launch phase or atmospheric reentry of space ve-
priate safety and health practices and determine the applica-
hicles,
bility of regulatory limitations prior to use.
1.2.2 Landers on planet surfaces,
1.2.3 Degradation of thermal coatings,
2. Referenced Documents
1.2.4 Increased friction in space of mechanical devices,
2.1 ASTM Standards:
sometimes called “cold welding,”
E259 Practice for Preparation of Pressed Powder White
1.2.5 Sun sensors,
Reflectance Factor Transfer Standards for Hemispherical
1.2.6 Man in space,
and Bi-Directional Geometries
1.2.7 Energy conversion devices, and
E296 Practice for Ionization Gage Application to Space
1.2.8 Tests of components for leaks, outgassing, radiation
Simulators
damage, or bulk thermal properties.
E297 Methods for Calibrating Ionization Vacuum Gage
1.3 Range of Application:
Tubes
1.3.1 The extreme diversification of space-craft, design
E349 Terminology Relating to Space Simulation
philosophies, and analytical effort makes the preparation of a
2.2 ISO Standard:
This practice is under the jurisdiction of ASTM Committee E21 on Space
Simulation andApplications of SpaceTechnology and is the direct responsibility of For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Subcommittee E21.04 on Space Simulation Test Methods. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Sept. 1, 2004. Published September 2004. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 1973. Last previous edition approved in 1999 as E491–73 (1999). the ASTM website.
DOI: 10.1520/E0491-73R04E01. Withdrawn.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
´1
E491 – 73 (2004)
ISO 1000-1973 SI Units and Recommendations for the Use 3.2.6 apparent source—the minimum area of the final
of Their Multiples and of Certain Other Units elementsofthesolaropticalsystemfromwhichissues95%or
2.3 American National Standards: more of the energy that strikes an arbitrary point on the test
specimen.
ANSI Y10.18-1967 Letter Symbols for Illuminating Engi-
3.2.7 astronomical unit (AU)—a unit of length defined as
neering
the mean distance from the earth to the sun (that is,
ANSI Z7.1-1967 Standard Nomenclature and Definitions
149597890 6 500 km).
for Illuminating Engineering
3.2.8 blackbody (USA), Planckian radiator—a thermal ra-
ANSI Y10.19-1969 Letter Symbols for Units Used in Sci-
diator which completely absorbs all incident radiation, what-
ence and Technology
ever the wavelength, the direction of incidence, or the polar-
ization. This radiator has, for any wavelength, the maximum
3. Terminology
spectral concentration of radiant exitance at a given tempera-
3.1 Definitions, Symbols, Units, and Constants—This sec-
ture (E349).
tioncontainstherecommendeddefinitions,symbols,units,and
3.2.9 collimate—to render parallel, (for example, rays of
constantsforuseinsolarsimulationforthermalbalancetesting
light).
of spacecraft. The International System of Units (SI) and
3.2.10 collimation angle—in solar simulation, the angular
International and American National Standards have been
nonparallelism of the solar beam, that is, the decollimation
adheredtoasmuchaspossible.TerminologyE349isalsoused
angle. In general, a collimated solar simulator uses an optical
andissoindicatedinthetext.Table1providescommonlyused
componenttoimageatinfinityanapparentsource(pseudosun)
symbols.
offinitesize.Theanglesubtendedbytheapparentsourcetothe
3.2 Definitions:
finalopticalcomponentreferredtoasthecollimator,isdefined
3.2.1 absorptance (a , a ,a )—ratio of the absorbed radiant
e v
asthesolarsubtenseangleandestablishesthenominalangleof
or luminous flux to the incident flux (E349)(Table 1).
decollimation. A primary property of the “collimated” system
3.2.2 absorptivity of an absorbing material—internal ab-
is the near constancy of the angular subtense angle as viewed
sorptance of a layer of the material such that the path of the
from any point in the test volume. The solar subtense angle is
radiation is of unit length (E349).
therefore a measure of the nonparallelism of the beam. To
3.2.3 air mass one (AM1)—the equivalent atmospheric
avoid confusion between various scientific fields, the use of
attenuationoftheelectromagneticspectrumtomodifythesolar
solar subtense angle instead of collimation angle or decollima-
irradiance as measured at one astronomical unit from the sum
tion angle is encouraged (see solar subtense angle).
outside the sensible atmosphere to that received at sea level,
3.2.11 collimator—an optical device which renders rays of
when the sun is in the zenith position.
light parallel.
3.2.4 air mass zero (AM0)—the absence of atmospheric
3.2.12 decollimation angle—not recommended (see colli-
attenuation of the solar irradiance at one astronomical unit
mation angle).
from the sun.
3.2.13 diffuse reflector—a body that reflects radiant energy
3.2.5 albedo—the ratio of the amount of electromagnetic
in such a manner that the reflected energy may be treated as if
radiation reflected by a body to the amount incident upon it.
it were being emitted (radiated) in accordance with Lambert’s
law.The radiant intensity reflected in any direction from a unit
area of such a reflector varies as the cosine of the angle
between the normal to the surface and the direction of the
4 reflected radiant energy (E349).
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036.
TABLE 1 Commonly Used Symbols
Symbol Quantity Definition Equation or Value Unit Unit Symbol
Q radiant energy, work, joule J
quantity of heat
−1
F radiant flux F =dQ/dt watt (joule/second) W, Js
−2
E irradiance (receiver) flux E =dF/dA watt per square metre W·m
density
−2
M radiant exitance (source) M =dF/dA watt per square metre W·m
−1
I radiant intensity (source) I =dF/dv watt per steradian W·sr
v = solid angle through which flux from source is radiated
−1 −2
L radiance L =dI/(dA cosu ) watt per steradian = W·sr ·m
square metre
u = angle between line of sight and normal to surface dA
t transmittance t = F, transmitted/F, incident none
t(l) spectral transmittance t(l)= F(l), transmitted/F(l), incident none
r reflectance (total) r = F, reflected/F, incident none
´H emittance (total ´H = M, specimen/M, blackbody
hemispherical)
a absorptance a = F, absorbed/F, incident none
a solar absorptance a = solar irradiance absorbed/solar irradiance incident none
s s
´1
E491 – 73 (2004)
3.2.14 dispersion function (X/l)—a measure of the separa- 3.2.28 intensity—see radiant intensity.
tion of wavelengths from each other at the exit slit of the
3.2.29 irradiance at a point on a surface E,E;E =dF /
e e e
monochromator, where X is the distance in the slit plane and l
dA—quotient of the radiant flux incident on an element of the
is wavelength. The dispersion function is, in general, different
surface containing the point, by the area of that element
−2
for each monochromator design and is usually available from
measured in W·m (E349)(Table 1).
the manufacturer. ¯
3.2.30 irradiance, mean total (E)—the average total irradi-
3.2.15 divergence angle—see solar beam divergence angle
ance over the test volume, as defined by the following
(3.2.60).
equation:
3.2.16 electromagnetic spectrum—the ordered array of
¯
E 5 * E ~r,u,z!dV/* dV (1)
v v
known electromagnetic radiations, extending from the shortest
wavelengths, gamma rays, through X rays, ultraviolet radia-
where:
¯
tion, visible radiation, infrared and including microwave and
E(r,u,z) = total irradiance as a function of position (Table
all other wavelengths of radio energy (E349).
1).
3.2.17 emissivity of a thermal radiator ´, ´=M /M
e,th e 3.2.31 irradiance, spectral [E or E(l)]—the irradiance at a
l
(´=1)—ratio of the thermal radiant exitance of the radiator to
specific wavelength over a narrow bandwidth, or as a function
that of a full radiator at the same temperature, formerly
of wavelength.
“pouvoir emissif” (E349).
3.2.32 irradiance, temporal—the temporal variation of in-
3.2.18 emittance (´)—the ratio of the radiant exitance of a
dividual irradiances from the mean irradiance. The temporal
specimen to that emitted by a blackbody radiator at the same
variations should be measured over time intervals equal to the
temperature identically viewed. The term generally refers to a
thermal time constants of the components. The temporal
specific sample or measurement of a specific sample. Total
stability of total irradiance can be defined as:
hemispherical emittance is the energy emitted over the hemi-
¯
E 56100[~DE 1DE !/2E# (2)
t t ~min! t ~max!
sphere above emitting element for all wavelengths. Normal
emittance refers to the emittance normal to the surface to the
3.2.33 irradiance, total—the integration over all wave-
emitting body.
lengths of the spectral irradiance.
3.2.19 exitance at a point on a surface (radiant exitance)
3.2.34 irradiance, uniformity of—uniformity of total irradi-
(M)—quotient of the radiant flux leaving an element of the
ance can be defined as:
surface containing the point, by the area of that element,
¯
−2 E 56100[ E 1 E /2E (3)
~ ! #
u min max
~ ! ~ !
measured in W·m (E349)(Table 1).
3.2.20 field angle—not recommended (see solar beam sub-
where:
tense angle).
E = uniformity of the irradiance within the test vol-
u
3.2.21 flight model—an operational flight-capable space-
ume, expressed as a percent of the mean irradi-
craft that is usually subjected to acceptance tests.
ance,
3.2.22 flux (radiant, particulate, and so forth)—for electro-
E = smallest value obtained for irradiance within the
(min)
magnetic radiation, the quantity of radiant energy flowing per
test volume, and
unit time; for particles and photons, the number of particles or E = largest value obtained for irradiance within the
(max)
photons flowing per unit time (E349).
test volume.
3.2.23 gray body—a body for which the spectral emittance
Uniformity of irradiance values must always be specified
and absorptance is constant and independent of wavelength.
together with the largest linear dimension of the detector used.
The term is also used to describe bodies whose spectral
3.2.35 Lambert’s law—the radiant intensity (flux per unit
emittance and absorptance are constant within a given wave-
solid angle) emitted in any direction from a unit-radiating
length band of interest (E349).
surface varies as the cosine of the angle between the normal to
3.2.24 incident angle—the angle at which a ray of energy
the surface and the direction of the radiation (also called
impinges upon a surface, usually measured between the direc-
Lambert’scosinelaw).Lambert’slawisnotobeyedexactlyby
tion of propagation of the energy and a perpendicular to the
most real surfaces, but an ideal blackbody emits according to
surface at the point of impingement or incidence.
this law. This law is also satisfied (by definition) by the
3.2.25 infrared radiation—see electromagnetic spectrum
distributionofradiationfromaperfectlydiffuseradiatorandby
(E349). the radiation reflected by a perfectly diffuse reflector. In
3.2.26 insolation—direct solar irradiance received at a sur- accordance with Lambert’s law, an incandescent spherical
blackbody when viewed from a distance appears to be a
face, contracted from incoming solar radiation.
uniformlyilluminateddisk.Thislawdoesnottakeintoaccount
3.2.27 integrating (Ulbrecht) sphere—part of an integrating
any effects that may alter the radiation after it leaves the
photometer. It is a sphere which is coated internally with a
source.
white diffusing paint as nonselective as possible, and which is
provided with associated equipment for making a photometric 3.2.36 maximum test plane divergence angle—the angle
measurement at a point of the inner surface of the sphere. A between the extreme ray from the appar
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.