1、METRIC IMIL-STD-1809 (USAF)15 FEB 91MILITARY STANDARDSPACE ENVIRONMENTFORUSAF SPACE VEHICLESProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809(USAF)15 FEB 91DEPARTMENT OF THE AIR FORCEWashington, D.C. 20360MIL-STD1809 (USAF)Space Environmen
2、t for USAF Space Vehicles1. This military standard is approved for use within theDepartment of the Air Force, and is available for use by allDepartments and Agencies of the Department of Defense.2. Beneficial comments (recommendations, additions, deletions)and any pertinent data which may be of use
3、in improving thisdocument should be addressed to:USAF Space Systems Division, SSD/SDMSP. o. BOX 92960Worldway Postal CenterLos Angeles, CA90009-2960by using the self-addressed Standardization Document ImprovementProposal (DD Form 1426) appearing at the end of this document orby letter.iiProvided by
4、IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91This Standard addresses the natural unperturbed spaceenvironment. It is a compilation of the space environment dataobtained from the most authoritative contemporary sourcesavailable at t
5、he time of compilation. This standard establishesthe time-sensitive and orbit-sensitive parameters for thenaturally occuring environments. The standard is intended to:a) Ensure that space environmental interactions areconsidered and incorporated into the design ofspace systems and subsystems.b) Prov
6、ide a basis for evaluating the hardness ofspace systems and subsystems against the spaceenvironmental interactions.Space vehicles operating in the space environment experiencevarious effects caused by the vacuum,radiation, and particulateenvironments, as well as inertial effects. These effects areno
7、t specifically addressed in this standard, but should beincluded in the analyses of the effects of the environment onthe space system,to the extent applicable.This standard does not address effects of human operationsin space such as orbiting space debris, transmitter radiations,fluid discharges fro
8、m space vehicles, outgassing, or surfacecontamination. Neither does it address the interaction betweenthe environment and an orbiting space vehicle, such as atomicoxygen burning of surface materials,surface glow, plasma wavesgenerated by the presence of the space vehicle, space vehiclecharging, or o
9、rbital dynamics. Nor, finally, does it addressthe effects of the environment on the space vehicle andsubsystems, such as ionizing radiation damage, single eventupsets in electronics, or backgrounds such as luminescence andCerenkov radiation in optical materials. It does, however,provide the necessar
10、y environmental parameter data forcalculations of space system performance as modified by thepresence of these environmental elements.Although this standard does not address the effects of humanoperations or the induced environment that is due to theinteraction between the environment and a body in
11、space, thisshould not be interpreted as indicating that these elements arenot important.Their effects on a space system may be greaterthan that due to the natural environment. These elements varywith human activities, tend to be program peculiar, and,therefore, are simply not appropriate for inclusi
12、on in thisstandard. However, these elements should also be included inthe analyses of the effects of the total environment on spacesystems, to the extent they are applicable.iiiProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB
13、 91THIS PAGE INTENTIONALLY LEFT BLANKivProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permit
14、ted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91SECTION 1SCOPE1.1The purpose and scope of t
15、his document is to state theparameters of the earths natural environment, above 100kilometers, for use in space vehicle and space system design.The natural environment includes neutral atmosphere, plasma,energetic charged particles, meteoroids, geomagnetic field,electromagnetic radiation, gravitatio
16、nal field, cosmic rays, andsolar energetic particles. The geosynchronous environment andthe ionosphere are treated in detail. The trapped radiationbelts, drag due to the neutral density, atomic oxygen, andparticle impacts are treated as well.1.2 APPLICATIONThis standard is intended for use in acquis
17、ition contractsfor selected space vehicles and upper stage vehicles. Thestandard should be cited in the technical requirements (program-peculiar specifications) as may be appropriate to specify thenatural space environment parameters that are applicable for thespace system acquisition.Provided by IH
18、SNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91THIS PAGE INTENTIONALLY LEFT BLANKProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91SECTION 2REFERENCED DOCUMENT
19、S2.1 GOVERNMENT NONGOVERNMENT DOCUMENTSNone. All references are listed in Subsection 6.2 insteadof this subsection since they are intended only for informationand guidance.2*2 ORDER OF PRECEDENCEIn the event of a conflict between the text of this standardand the references cited herein, the text of
20、this standard shalltake precedence. However, nothing in this standard shallsupersede applicable laws and regulations unless a specificexemption has been obtained.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91THIS PAGE IN
21、TENTIONALLY LEFT BLANK6Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91SECTION 3DEFINITIONSNot applicable. A list of definitions is not provided bythis standard. The definitions of terms stated in the guidancedocuments lis
22、ted for reference in Subsection 6.2 should be usedto the extent applicable.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91THIS PAGE INTENTIONALLY LEFT BLANK6Provided by IHSNot for ResaleNo reproduction or networking permi
23、tted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91SECTION 4GENERAL REQUIREMENTSThis standard establishes the time-sensitive andorbit-sensitive parameters for the naturally occuring spaceenvironment above 100 kilometers. Space vehicles shall becapable of operating in this naturally occuri
24、ng environmentencountered in orbit (See 6.1). Since not all of theenvironmental parameters are of concern in all possible orbits,Table I is provided as a guide to identify the usual parametersof concern for generic orbit types.Space vehicles operating in the space environment experiencevarious effec
25、ts caused by the vacuum, radiation, and particulateenvironments, as well as inertial effects. These effects arenot specifically addressed in this standard, but shall beincluded in the analyses of the effects of the environment onthe space system, to the extent applicable.The numerical data presented
26、 in Section 5 are current as ofthe date of issue of this standard. As new data on the spaceenvironment are obtained,the models recommended or referencedmay be superseded. New models which are intended to supercedethe models recommended or referenced in this document may beused as approved substitute
27、s provided they are issued by thesame agency or sanctioned by the same authoritative body as themodels which they supercede.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without l
28、icense from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91SECTION 5DETAILED REQUIREMENTS5.1 ENERGETIC CHARGED PARTICLES.Energetic charged particles produce effects in materialsprimarily through their ionizing action. Effects includeradiation damage in electronics, solar cells, and opticalmaterials; electrosta
29、tic discharge; backgrounds in sensors;single-event upsets in digital electronics; optical noise; andother deleterious effects.5.1.1 Cosmic Rays Cosmic rays are highly relativisticcharged particles of solar and galactic origin. They are highlyionizing and highly penetrating. The primary concerns with
30、cosmic rays are their background signatures in electronic andoptical devices and the single-event upset phenomenon, in whichthe high density of ionization along a track in an electronicdevice acts as a signal in that device.5.1.1.1 Galactic Cosmic Rays For the purposes of thisStandard, the cosmic ra
31、y environment is defined by Figures 1, 2,3, and 4, and Table II. Figure 1 presents the differentialenergy spectra for hydrogen and helium nuclei, which constituterespectively 83 percent and 13 percent of the primary cosmicrays. Figure 2 presents the electron component whichconstitutes 3 percent of t
32、he cosmic rays. Figure 2 is acomposite figure, including both galactic and solar electrons.Because of their importance to single-event upset events inmicroelectronics,the cosmic ray spectrum of iron nuclei ispresented in Figure 4. Table II provides the cosmic raycomposition for helium plus nuclei up
33、 to and including the irongroup. The elements above He in the spectrum constitute about 1percent of the primary cosmic rays. For specific missions wheredetailed analyses of cosmic ray effects are required, theguidelines, recommendations, and methods of generatingappropriate mission-specific environm
34、ental models, as describedin Refs. 6.2 a, 6.2 b, 6.2 C, and 6.2 d, shall be applicable.The least severe environment under which the space vehicle shallbe capable of operating is that associated with the so-called“solar minimum” (see Paragraph 5.1.1.1.1 below). The data forcomposite particles present
35、ed in Figures 1, 2, 3, and 4 aregiven in terms of differential energy flux (number of particlesper unit energy) per nucleon. Protons and electrons (Figures 1and 3) are not composite particles.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10Provided
36、 by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91FIGURE 2. Cosmic Ray Differential Energy Spectra for Electrons11Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)1
37、5 FEE 91FIGURE 3. Anomalous Component of Cosmic Ray Differential EnergySpectra for H. He. C. & O12Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91FIGURE 4. Spectrum of Cosmic Ray Iron Nuclei13Provided by IHSNot for ResaleN
38、o reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91TABLE II. Heavy Cosmic Ray AbundanceSPECIES Relative AbundanceGreater than 450 MeV/NucFigures5.1.1.1.1 Variability of Galactic Cosmic Rays1, 2, and 3 indicate the variability of the cosmic-ray fluxintensi
39、ty as a function of solar cycle. The intensity of thelow energy end of the spectrum undergoes a periodic modulationwith the elevenyear sunspot cycle, where the intensity isapproximately anti-correlated with the sunspot number and variesin intensity by about a factor of five over the eleven-yearcycle
40、. A second variation is the “anomalous component” shown inFigure 3.Enhancements exceeding a factor of ten relative tothe carbon flux have been observed in the fluxes of hydrogen,helium,and oxygen ions. The protons in the anomalous componentare most intense around 100 MeV. The alpha particle intensit
41、ypeaks between 10 and 50 MeV/nucleon, and oxygen around 1014Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-1809 (USAF)15 FEB 91MeV/nucleon. Because of the relatively low energy range, atomicnumber, and overall intensity of the anomalous comp
42、onentconstituents, the latter usually are of small significance inthe overall environment,but may be significant in specialapplications. The anomalous component shall be included in thecosmic ray environment which is used to analyze the performanceof a space vehicle or space system.Several other typ
43、es of temporal variability in the galacticcosmic ray flux have been observed and are described in Ref. 6.2 a.These fluctuations in particle flux occur at energies below 100MeV/nucleon and are referred to asinterplanetary weather.”Their effect on space vehicles and space systems using currenttechnolo
44、gy is minimal in most cases, but shall be considered incases where sensitive components are used and extremely highreliability of operation is required.The software in Ref. 6.2 dprovides for the effect of this variability on the environmentalmodel by requesting the “interplanetary weather index” val
45、ue asinput.5.1.1.1.2 GalacticAccess of Cosmic Rays. Spatial variationin the particle flux intensities within the magnetosphere occurbecause of the Earths magnetic field and physical shadow at lowaltitude.Where necessary, the primary environments specified inParagraph 5.1.1.1 can be modified by incor
46、porating geomagneticcutoff rigidities and the effect of Earths shadow in the model.Provision for calculating these effects has been made in the CREMEcomputer software of Ref. 6.2 d.5.1.1.2 Solar Cosmic Rays. Solar cosmic rays are presentin space about two percent of the time.The solar cosmic raycomp
47、onent of the environment can be ignored in analyses only ifdisruption of space vehicle or space system operation more thantwo percent of the time can be tolerated (see Paragraph 5.1.1.2.1below), and total accumulated dose below about 100 krads (Si) isof no concern. Otherwise, the recommendations and
48、 methodscontained in Ref. 6.2 a,6.2 b, 6.2 c, and 6.2 d shall befollowed. Attention should be paid to the question of survivalduring at least one large flare, as defined by Ref. 6.2 a. Seealso Paragraph 5.1.3.5.1.1.2.1 Variability of Solar Cosmic RayS. Major solarflares are characterized by a random frequency distribution,modulated by the eleven-year sunspot cycle. Near the peak ofthe cycle, major flares occur at the rate of sev
