ASTM E491-73(2010)
(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 Nonapplicability—This 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 7.6.
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 Utility—This 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.
1.5 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 pri...
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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
Designation: E491 − 73(Reapproved 2010)
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.
1. Scope 1.3.2 The ultimate result of the thermal balance test is to
prove the thermal design to the satisfaction of the thermal
1.1 Purpose:
designers. Flexibility must be provided to them to trade off
1.1.1 The primary purpose of this practice is to provide
additional analytical effort for simulator shortcomings. The
guidance for making adequate thermal balance tests of space-
combination of a comprehensive thermal-analytical model,
craft and components where solar simulation has been deter-
modern computers, and a competent team of analysts greatly
mined to be the applicable method. Careful adherence to this
reduces the requirements for accuracy of space simulation.
practice should ensure the adequate simulation of the radiation
environment of space for thermal tests of space vehicles.
1.4 Utility—This practice will be useful during space ve-
1.1.2 A corollary purpose is to provide the proper test
hicle test phases from the development through flight accep-
environmentforsystems-integrationtestsofspacevehicles.An
tance test. It should provide guidance for space simulation
accurate space-simulation test for thermal balance generally
testing early in the design phase of thermal control models of
willprovideagoodenvironmentforoperatingallelectricaland
subsystems and spacecraft. Flight spacecraft frequently are
mechanical systems in their various mission modes to deter-
tested before launch. Occasionally, tests are made in a space
mine interferences within the complete system. Although
chamber after a sister spacecraft is launched as an aid in
adherence to this practice will provide the correct thermal
analyzing anomalies that occur in space.
environment for this type of test, there is no discussion of the
1.5 This standard does not purport to address all of the
extensive electronic equipment and procedures required to
safety concerns, if any, associated with its use. It is the
support systems-integration testing.
responsibility of the user of this standard to establish appro-
1.2 Nonapplicability—This practice does not apply to or
priate safety and health practices and determine the applica-
provide incomplete coverage of the following types of tests:
bility of regulatory limitations prior to use.
1.2.1 Launch phase or atmospheric reentry of space
vehicles,
2. Referenced Documents
1.2.2 Landers on planet surfaces,
1.2.3 Degradation of thermal coatings,
2.1 ASTM Standards:
1.2.4 Increased friction in space of mechanical devices,
E259Practice for Preparation of Pressed Powder White
sometimes called “cold welding,”
Reflectance Factor Transfer Standards for Hemispherical
1.2.5 Sun sensors,
and Bi-Directional Geometries
1.2.6 Man in space,
E296Practice for Ionization Gage Application to Space
1.2.7 Energy conversion devices, and
Simulators
1.2.8 Tests of components for leaks, outgassing, radiation
E297Test Method for Calibrating Ionization Vacuum Gage
damage, or bulk thermal properties.
Tubes (Withdrawn 1983)
E349Terminology Relating to Space Simulation
1.3 Range of Application:
1.3.1 The extreme diversification of space-craft, design
2.2 ISO Standard:
philosophies, and analytical effort makes the preparation of a
ISO 1000-1973SI Units and Recommendations for the Use
brief, concise document impossible. Because of this, various
of Their Multiples and of Certain Other Units
spacecraftparametersareclassifiedandrelatedtotheimportant
characteristic of space simulators in a chart in 7.6.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This practice is under the jurisdiction of ASTM Committee E21 on Space contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Simulation andApplications of SpaceTechnology and is the direct responsibility of Standards volume information, refer to the standard’s Document Summary page on
Subcommittee E21.04 on Space Simulation Test Methods. the ASTM website.
Current edition approved April 1, 2010. Published May 2010. Originally The last approved version of this historical standard is referenced on
ε1
approved in 1973. Last previous edition approved in 2004 as E491–73 (2004) . www.astm.org.
DOI: 10.1520/E0491-73R10. Withdrawn.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E491 − 73 (2010)
2.3 American National Standards: 3.2.7 astronomical unit (AU)—a unit of length defined as
ANSI Y10.18-1967Letter Symbols for Illuminating Engi- the mean distance from the earth to the sun (that is,
neering 149597890 6 500 km).
ANSIZ7.1-1967StandardNomenclatureandDefinitionsfor
3.2.8 blackbody (USA),Planckian radiator—a thermal ra-
Illuminating Engineering
diator which completely absorbs all incident radiation, what-
ANSI Y10.19-1969Letter Symbols for Units Used in Sci-
ever the wavelength, the direction of incidence, or the polar-
ence and Technology
ization. This radiator has, for any wavelength, the maximum
spectral concentration of radiant exitance at a given tempera-
3. Terminology
ture (E349).
3.1 Definitions, Symbols, Units, and Constants—This sec-
3.2.9 collimate—to render parallel, (for example, rays of
tioncontainstherecommendeddefinitions,symbols,units,and
light).
constantsforuseinsolarsimulationforthermalbalancetesting
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
finalopticalcomponentreferredtoasthecollimator,isdefined
3.2 Definitions:
asthesolarsubtenseangleandestablishesthenominalangleof
3.2.1 absorptance (α , α ,α )—ratio of the absorbed radiant
e v
decollimation. A primary property of the “collimated” system
or luminous flux to the incident flux (E349)(Table 1).
is the near constancy of the angular subtense angle as viewed
3.2.2 absorptivity of an absorbing material—internal ab-
from any point in the test volume. The solar subtense angle is
sorptance of a layer of the material such that the path of the
therefore a measure of the nonparallelism of the beam. To
radiation is of unit length (E349).
avoid confusion between various scientific fields, the use of
3.2.3 air mass one (AM1)—the equivalent atmospheric at-
solar subtense angle instead of collimation angle or decollima-
tenuation of the electromagnetic spectrum to modify the solar
tion angle is encouraged (see solar subtense angle).
irradiance as measured at one astronomical unit from the sum
3.2.11 collimator—an optical device which renders rays of
outside the sensible atmosphere to that received at sea level,
light parallel.
when the sun is in the zenith position.
3.2.12 decollimation angle—not recommended (see colli-
3.2.4 air mass zero (AM0)—the absence of atmospheric
mation angle).
attenuation of the solar irradiance at one astronomical unit
from the sun.
3.2.13 diffuse reflector—a body that reflects radiant energy
in such a manner that the reflected energy may be treated as if
3.2.5 albedo—the ratio of the amount of electromagnetic
it were being emitted (radiated) in accordance with Lambert’s
radiation reflected by a body to the amount incident upon it.
law.The radiant intensity reflected in any direction from a unit
3.2.6 apparent source—the minimum area of the final ele-
area of such a reflector varies as the cosine of the angle
ments of the solar optical system from which issues 95% or
between the normal to the surface and the direction of the
more of the energy that strikes an arbitrary point on the test
reflected radiant energy (E349).
specimen.
3.2.14 dispersion function (X/λ)—a measure of the separa-
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
tion of wavelengths from each other at the exit slit of the
4th Floor, New York, NY 10036, http://www.ansi.org.
monochromator, where X is the distance in the slit plane and λ
TABLE 1 Commonly Used Symbols
Symbol Quantity Definition Equation or Value Unit Unit Symbol
Q radiant energy, work, joule J
quantity of heat
−1
Φ radiant flux Φ =dQ/dt watt (joule/second) W, Js
−2
E irradiance (receiver) flux E =dΦ/dA watt per square metre W·m
density
−2
M radiant exitance (source) M =dΦ/dA watt per square metre W·m
−1
I radiant intensity (source) I =dΦ/dω watt per steradian W·sr
ω = solid angle through which flux from source is radiated
−1 −2
L radiance L =dI/(dA cosθ ) watt per steradian = W·sr ·m
square metre
θ = angle between line of sight and normal to surface dA
τ transmittance τ = Φ, transmitted/Φ, incident none
τ(λ) spectral transmittance τ(λ)= Φ(λ), transmitted/Φ(λ), incident none
ρ reflectance (total) ρ = Φ, reflected/Φ, incident none
εH emittance (total εH = M, specimen/M, blackbody
hemispherical)
α absorptance α = Φ, absorbed/Φ, incident none
α solar absorptance α = solar irradiance absorbed/solar irradiance incident none
s s
E491 − 73 (2010)
is wavelength. The dispersion function is, in general, different screen placed inside the sphere prevents the point under
for each monochromator design and is usually available from observation from receiving any radiation directly from the
the manufacturer. source (E349).
3.2.15 divergence angle—see solar beam divergence
3.2.28 intensity—see radiant intensity.
angle(3.2.60).
3.2.29 irradiance at a point on a surface E ,E;E =dΦ /
e e e
3.2.16 electromagnetic spectrum—the ordered array of
dA—quotient of the radiant flux incident on an element of the
known electromagnetic radiations, extending from the shortest
surface containing the point, by the area of that element
−2
wavelengths, gamma rays, through X rays, ultraviolet
measured in W·m (E349)(Table 1).
radiation, visible radiation, infrared and including microwave
¯
3.2.30 irradiance, mean total (E)—the average total irradi-
and all other wavelengths of radio energy (E349).
ance over the test volume, as defined by the following
3.2.17 emissivity of a thermal radiator ε, ε =M /
e,th equation:
M (ε = 1)—ratio of the thermal radiant exitance of the radiator
e
¯
E 5 E r,θ,z dV/ dV (1)
* ~ ! *
to that of a full radiator at the same temperature, formerly
v v
“pouvoir emissif” (E349).
where:
3.2.18 emittance (ε)—the ratio of the radiant exitance of a
¯
E(r,θ,z) = total irradiance as a function of position (Table
specimen to that emitted by a blackbody radiator at the same
1).
temperature identically viewed. The term generally refers to a
3.2.31 irradiance, spectral [E or E(λ)] —the irradiance at a
specific sample or measurement of a specific sample. Total
λ
specific wavelength over a narrow bandwidth, or as a function
hemispherical emittance is the energy emitted over the hemi-
of wavelength.
sphere above emitting element for all wavelengths. Normal
emittance refers to the emittance normal to the surface to the
3.2.32 irradiance, temporal—the temporal variation of in-
emitting body.
dividual irradiances from the mean irradiance. The temporal
variations should be measured over time intervals equal to the
3.2.19 exitance at a point on a surface (radiant exitance)
(M)—quotient of the radiant flux leaving an element of the thermal time constants of the components. The temporal
stability of total irradiance can be defined as:
surface containing the point, by the area of that element,
−2
measured in W·m (E349)(Table 1).
¯
E 56100 ∆E 1∆E /2E (2)
@ #
~ !
t t ~min! t ~max!
3.2.20 field angle—not recommended (see solar beam sub-
3.2.33 irradiance, total—the integration over all wave-
tense angle).
lengths of the spectral irradiance.
3.2.21 flight model—an operational flight-capable space-
3.2.34 irradiance, uniformity of—uniformity of total irradi-
craft that is usually subjected to acceptance tests.
ance can be defined as:
3.2.22 flux (radiant, particulate, and so forth)—for electro-
¯
magnetic radiation, the quantity of radiant energy flowing per
E 56100@ E 1E /2E# (3)
~ !
u ~min! ~max!
unit time; for particles and photons, the number of particles or
where:
photons flowing per unit time (E349).
E = uniformity of the irradiance within the test volume,
u
3.2.23 gray body—a body for which the spectral emittance
expressed as a percent of the mean irradiance,
and absorptance is constant and independent of wavelength.
E = smallest value obtained for irradiance within the
(min)
The term is also used to describe bodies whose spectral
test volume, and
emittance and absorptance are constant within a given wave-
E = largest value obtained for irradiance within the test
(max)
length band of interest (E349).
volume.
3.2.24 incident angle—the angle at which a ray of energy
Uniformity of irradiance values must always be specified
impinges upon a surface, usually measured between the direc-
together with the largest linear dimension of the detector used.
tion of propagation of the energy and a perpendicular to the
3.2.35 Lambert’s law—the radiant intensity (flux per unit
surface at the point of impingement or incidence.
solid angle) emitted in any direction from a unit-radiating
3.2.25 infrared radiation—see electromagnetic spectrum
surface varies as the cosine of the angle between the normal to
(E349).
the surface and the direction of the radiation (also called
3.2.26 insolation—direct solar irradiance received at a
Lambert’scosinelaw).Lambert’slawisnotobeyedexactlyby
surface, contracted from incoming solar radiation.
most real surfaces, but an ideal blackbody emits according to
this law. This law is also satisfied (by definition) by the
3.2.27 integrating (Ulbrecht) sphere—part of an integrating
photometer. It is a sphere which is coated internally with a distributionofradiationfromaperfectlydiffuseradiatorandby
the radiation reflected by a perfectly diffuse reflector. In
white diffusing paint as nonselective as possible, and which is
provided with associated equipment for making a photometric accordance with Lambert’s law, an incandescent spherical
measurement at a point of the inner surface of the sphere. A blackbody when viewed from a distance appears to be a
...
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