# Environmental Conditions for Space Flight Hardware -- 

# A Survey

For the NASA Electronic Parts and Packaging (NEPP) Program, 2004

Jeannette Plante and Brandon Lee, Dynamic Range Corporation

[Introduction]{.underline}

Interest in generalization of the physical environment experienced by
NASA hardware from the natural Earth environment (on the launch pad),
man-made environment on Earth (storage acceptance and qualification
testing), the launch environment, and the space environment, is driven
by the need to find commonality among our hardware in an effort to
reduce cost and complexity. NASA is entering a period of increase in its
number of planetary missions and it is important to understand how our
qualification requirements will evolve with and track these new
environments.

Environmental conditions are described for NASA projects in several ways
for the different periods of the mission life cycle. At the beginning,
the mission manager defines survivability requirements based on the
mission length, orbit, launch date, launch vehicle, and other factors
such as the use of reactor engines. Margins are then applied to these
values (temperature extremes, vibration extremes, radiation tolerances,
etc.) and a new set of conditions is generalized for design
requirements. Mission assurance documents will then assign an additional
margin for reliability, and a third set of values is provided for during
qualification testing. A fourth set of environmental condition values
may evolve intermittently from heritage hardware that has been tested to
a level beyond the actual mission requirement. These various sets of
environment figures can make it quite confusing and difficult to capture
common hardware environmental requirements.

Environmental requirement information can be found in a wide variety of
places. The most obvious is with the individual projects. We can easily
get answers to questions about temperature extremes being used and
radiation tolerance goals, but it is more difficult to map the answers
to the process that created these requirements: for design, for
qualification, and for actual environment with no margin applied. Not
everyone assigned to a NASA project may have that kind of insight, as
many have only the environmental requirement numbers needed to do their
jobs but do not necessarily have a programmatic-level understanding of
how all of the environmental requirements fit together.

For this project, we sought environmental requirement numbers from a
variety of sources. These were the project parts engineers (PPEs),
safety assurance managers (SAMs), project documentation, and published
papers and standards. Our primary resource for space environment
information was NASA Memorandum 106655, Operational Environments for
Electrical Power Wiring on NASA Space Systems, June 1994 \[1\].
Vibration and thermal-vacuum test conditions were excerpted from General
Environmental Verification Specification (GEVS) for STS and ELV
Payloads, Subsystems and Components
(<http://arioch.gsfc.nasa.gov/302/gevs-se/toc.htm>) \[2\]. The final
principal reference was an environments review performed for NEPP in
1992 titled The Influence of Space Environmental Factors on NASA
Electrical, Electronic, and Electromechanical Part Selection and
Application, A. Garrison, J. Barrows, December 1992 \[3\].

NASA Memorandum 106655 breaks down all applications into six different
types: pressurized modules, low-Earth orbit (LEO), geosynchronous earth
orbit (GEO), trans-atmospheric vehicle (orbiter), lunar surface, and
Martian surface. (A useful addition to these categories may be deep
space as a broad application area). The environmental conditions listed
in this document are shown in Table 1 below.

**Table 1.** List of Attributes Making Up the Environment

Suite Experienced by Flight Hardware

> [Vibration](#vibe), Sinusoidal Sweep and Random
>
> [Shock and Acoustics](#shock)
>
> [Particle Impact](#particle_impact) (In Space)
>
> [Temperature](#temp): Extremes and Cycling
>
> [Atmospheric Change and Vacuum](#pressure)
>
> [Humidity](#humid)
>
> [Ultra Violet Radiation](#EMC)
>
> [Ionizing Particle Radiation](#ionizing_rad)
>
> [Atomic Oxygen](#atomic_oxygen)
>
> [Gravity](#gravity)
>
> [Charged Plasma](#charged_plasma) (Or Space Charging)
>
> [Combined Environment Tests](#combinef)

Each environmental attribute will be discussed individually in this
paper in order to identify the range of stresses that flight hardware is
exposed to throughout build and launch and in the actual use
environments.

[]{#vibe .anchor}1. [Vibration]{.underline}

Vibration is only significant during qualification testing and during
launch since there is very little vibration in space (though temperature
cycling and current heating has been known to cause bending and
work-hardening stress that can mimic mechanical vibration). Vibration
requirements are generally defined by the launch vehicle starting quite
low at around 3 g's for acceptance testing of payloads on the Pegasus
rocket to over 12 g's for payloads on the Shuttle (which experiences
both the launch and return vibration periods). Vibration environments
are known to subassembly designers and manufacturers in the test
requirements. Two types of tests are done for vibration: random and sine
directions (x, y, and z), and levels specified for acceptance testing
and others for qualification testing. The frequencies sweep range during
these tests also varies among launch vehicles in order to model actual
frequencies that might stimulate damaging mechanical resonances
experienced. Tables 2 and 3 show the test levels used for acceptance and
qualification as described in GEVS.

Current NASA GSFC projects are specifying to the higher random vibration
requirement levels, between 8.7 g's and 15.8 g's for qualification. Very
little information was available on sine vibration requirements actually
being used by the projects. Reference \[4\] cites that if the random
vibration test does not show a self-resonance above 140 Hz, then the
sinusoidal test can be skipped. Reference \[4\] also states that the
shock and vibration expected in shipping and handling should be
controlled to be less than the worst case for the "launch, separation,
or mission dynamics environment."

**Table 2.** Random Vibration Conditions Requirements From GEVS \[2\]

  ------------------- ----------------- --------------------- ------------------
  ***Launch           ***Frequency      ***ASD Level          
  Vehicle***          (Hz)***           (G^2/^Hz)***          

  *** ***             *** ***           ***Qualification***   ***Acceptance***

  STS                 20 to 2,000       12.9 G~rms~           9.1 G~rms~

  ATLAS               20 to 2,000       2.7 G~rms~            N/A

  DELTA               20 to 2,000       8.7 G~rms~            N/A

  TITAN III           20 to 2,000       4.2 G~rms~             

  SCOUT               20 to 2,000       8.2 G~rms~            5.8 G~rms~

  PEGASUS             20 to 2,000       4.5 G~rms~            3.2 G~rms~

  ARIANE              20 to 2,000       7.3 G~rms~            N/A

  TAURUS              20 to 2,000       5.4 G~rms~            N/A

  TAURUS XL           20 to 2,000       5.4 G~rms~            N/A

  TAURUS XLS          20 to 2,000       6.5 G~rms~            N/A

  CONESTOGA           20 to 2,000       4.8 G~rms~            3.4 G~rms~

  H II (JAXA)         N/A               N/A                   N/A

  LMLV                20 to 2,000       7.2 G~rms~            5.1 G~rms~
  ------------------- ----------------- --------------------- ------------------

**Table 3.** Sine Vibration Conditions Requirements From GEVS \[2\]

  ------------ -------------- --------------------- ------------------ -------------- --------------------- ------------------
  ***Vehicle   ***Thrust                                               ***Lateral                           
  Name***      Axis***                                                 Axis***                              

               ***Frequency   ***Sine Vibration                        ***Frequency   ***Sine Vibration     
               (Hz)***        (G~0-p~)***                              (Hz)***        (G~0-p~)***           

                              ***Qualification***   ***Acceptance***                  ***Qualification***   ***Acceptance***

  DELTA        5\~6.2         12.5 mm (0.5/in) DA                      5-100          0.7                   

               6.2\~100       1.00                                                                          

  TITAN                                                                5\~ 25         7.9 cm/s              

  SCOUT        5\~43          24 cm/s                                  25\~80         1.25                  

               43\~100        6.25                                     80\~200        1.5                   

               100\~200       5                                                                             

  ARIANE       5\~6           1                     1                  5\~6           1                     1

               6\~100         1.25                  1                  6\~100         1.25                  1

  H II         5\~100         1                                        5\~100         0.8                   
  ------------ -------------- --------------------- ------------------ -------------- --------------------- ------------------

2\. []{#shock .anchor}[Shock and Acoustics]{.underline}

Shock requirements originate from conditions experienced in shipping and
handling as well as launch and separation of a payload from the launch
vehicle. The acoustic stress comes from the cavity geometry between the
payload or subsystem and the spacecraft or launch vehicle's fairing
walls. GEVS specifies the amount of acoustic blanketing to be used in
the cavity and qualification and acceptance test limits. The shock
condition is assumed to be very high in energy and frequency but short
in duration, and the damage is assumed to occur when a part of the test
sample begins to resonate. Without the resonating response, the shock
vibration frequency dissipates quickly. Table 4 shows shock and Table 5
shows acoustic vibration requirements that are given in GEVS by launch
vehicle. The data collected on project requirements tends towards the
levels associated with the Delta rocket.

**Table 4.** Shock Levels Defined by GEVS \[2\]

+------------+-------------------+---------------------+--------------+
| #          | ***Frequency      | ***Shock Levels     |              |
| ## Vehicle | (Hz)***           | (G)***              |              |
+------------+-------------------+---------------------+--------------+
|            |                   | ***Qualification*** | ***A         |
|            |                   |                     | cceptance*** |
+------------+-------------------+---------------------+--------------+
| DELTA      | 350               | 140                 | 100          |
+------------+-------------------+---------------------+--------------+
|            | 1,700             | 3500                | 2500         |
+------------+-------------------+---------------------+--------------+
|            | 4,000 -- 5,000    | 7700                | 5500         |
+------------+-------------------+---------------------+--------------+
|            | 10,000            | 2730                | 1950         |
+------------+-------------------+---------------------+--------------+
| TITAN      | 100               | 100                 | 70           |
+------------+-------------------+---------------------+--------------+
|            | 100 -- 1,250      | 280                 | 200          |
+------------+-------------------+---------------------+--------------+
|            | 5,000             | 90                  | 65           |
+------------+-------------------+---------------------+--------------+
| SCOUT      | 100               | 14                  | 10           |
+------------+-------------------+---------------------+--------------+
|            | 600 -- 2,000      | 280                 | 200          |
+------------+-------------------+---------------------+--------------+
| ARIANE^1^  | 100               | 25 -- 28            | 18 -- 20     |
+------------+-------------------+---------------------+--------------+
|            | 10,000            | 2800 -- 7000        | 2000 -- 5000 |
+------------+-------------------+---------------------+--------------+
| H II       | 100               | 56                  | 40           |
+------------+-------------------+---------------------+--------------+
|            | 1,500             | 56                  | 56           |
+------------+-------------------+---------------------+--------------+
|            | 3,000             | 580                 | 4100         |
+------------+-------------------+---------------------+--------------+

> **Note:**
>
> 1\. Adapter dependent. See GEVS for intermediate test frequencies and
> limits.

**Table 5.** Acoustic Vibration Requirements Defined by GEVS \[2\]

+-------+---------+-----------+-------------+---------------+---------+
| ***   | ***Fund |           | ***Test     | ***Noise      |         |
| Vehic | amental |           | Range       | Level (dB)*** |         |
| le*** | Fr      |           | (Hz)***     |               |         |
|       | equency |           |             |               |         |
|       | Max     |           |             |               |         |
|       | imum*** |           |             |               |         |
|       |         |           |             |               |         |
|       | ***     |           |             |               |         |
|       | (Hz)*** |           |             |               |         |
+-------+---------+-----------+-------------+---------------+---------+
|       | **      | *         |             | ***Qua        | **      |
|       | *Thrust | **Lateral |             | lification*** | *Accept |
|       | Axis*** | Axis***   |             |               | ance*** |
+-------+---------+-----------+-------------+---------------+---------+
| DELTA | 35      | 15        | 25 --       | 142.6         | 139.6   |
|       |         |           | 10,000      |               |         |
+-------+---------+-----------+-------------+---------------+---------+
| TITAN | 26      | 15        | 25 --       | 130           | 136     |
|       |         |           | 10,000      |               |         |
+-------+---------+-----------+-------------+---------------+---------+
| SCOUT | Not     | Not       | 50 --       | 140           | 137     |
|       | defined | defined   | 10,000      |               |         |
+-------+---------+-----------+-------------+---------------+---------+
| A     | 31      | 10        | 25 --       | 145           | 142     |
| RIANE |         |           | 10,000      |               |         |
+-------+---------+-----------+-------------+---------------+---------+
| H II  | 30      | 10        | 25 --       | 144           | 141     |
|       |         |           | 10,000      |               |         |
+-------+---------+-----------+-------------+---------------+---------+

[]{#particle_impact .anchor}

3\. [Particle Impact]{.underline}

Particle impact refers to micrometeorite hits during orbit or space
travel. The long-duration exposure failing (LDEF) experimental testbed
measured micrometeorite impacts in low-Earth orbit in the early 1980s
and found that during its 5.75-year exposure, LDEF saw one impact of
about 0.7 mm in diameter, per 7 m^2^ of exposed surface area in the RAM
direction (estimated rate of travel of 10 km/s). This sort of impact is
expected to be able to penetrate approximately 2.5 mm of aluminum.
Another example of micrometeorite impact observed on the Hubble Space
Telescope (HST) solar cell array is shown in Figure 1.

The lunar surface is more exposed to micrometeorites because there is no
atmosphere to interfere with the oncoming matter. Impact velocities
range from 24 to 72 km/s on the moon.

Table 6 shows particle impact expectations for LEO and other types of
missions.

**Table 6.** Particle Impact by Mission Type \[2\]

+-------------------------+--------------------------------------------+
| ***Mission Type***      | ***Conditions***                           |
+-------------------------+--------------------------------------------+
| LEO                     | 11 to 26 impacts/m^2^/year.                |
+-------------------------+--------------------------------------------+
| GEO                     | Lower than LEO.                            |
+-------------------------+--------------------------------------------+
| Trans-Atmospheric       | Altitude dependent.                        |
| Vehicle                 |                                            |
+-------------------------+--------------------------------------------+
| Lunar Surface           | 0.01 to 1.2 x 10^-4^ impacts/m^2^/year for |
|                         | small- to medium-sized matter, low for     |
|                         | larger meteoroids.                         |
+-------------------------+--------------------------------------------+
| Martian Surface         | Electrically charged dust particles        |
|                         | delivered by []{#dust_devil .anchor}dust   |
|                         | devils. ^\[8,9\]^ Their charge (created by |
|                         | friction) makes them attach to and seek    |
|                         | surfaces such as visors and the inside of  |
|                         | non-hermetic cavities to the degree that   |
|                         | visibility can be reduced or that          |
|                         | operation of the system could be impacted. |
|                         |                                            |
|                         | The flux of micrometeorite hits is         |
|                         | insignificant.                             |
+-------------------------+--------------------------------------------+

No data was collected for actual projects for particle impact
requirements, as that requirement is not usually available to the parts
engineer and generally parts are not qualified with respect to this
environmental condition.

![](media/image1.jpeg){width="3.472047244094488in"
height="2.5535433070866143in"}

[]{#temp .anchor}4. [Temperature Extremes and Cycling]{.underline}

Temperature extremes experienced by flight hardware are a combination of
their location with respect to the sun or a shadow (planet or
spacecraft) or in engineered environments (e.g., a dewar), and the
overall thermal management of the spacecraft, which might involve the
use of thermal radiators, heaters, or coolers. Table 7 shows temperature
extremes and the number of cycles expected on a yearly basis for the
different mission categories. \[2\]

The temperature range in LEO goes from --65 ºC to +125 ºC with thermal
cycling dependent on the orbit height. Temperature conditions in GEO are
similar to LEO on the hot side and colder when the spacecraft enters the
Earth's shadow about twice a year over a period of 45 days (each time).
During these 45-day periods, the spacecraft is in shadow daily for a
maximum of 70 minutes. Trans-atmospheric vehicles will experience
temperature extremes from --200 ºC to +260 ºC; however, temperature
cycling is not an issue because operation duration in orbit is for a few
minutes or hours. The temperature of the lunar surface changes greatly
during the day and night, rising up to +111 ºC and dropping to --171 ºC.
Twenty-eight days of the lunar day/night cycle results in 13 cycles in 1
Earth year.

**Table 7.** Temperature Extremes and Cycling by Mission Type \[2\]

  -------------------------- --------------------------------------------
  ***Mission Type***         ***Conditions***

  Pressurized Module         +18.3 ºC to 26.7 °C, cycling is not
                             significant.

  LEO                        -65 ºC to +125 ºC, cycles/yr. depending on
                             orbit height (6,000 for a height of 2 km,
                             780 for 20,000 km).

  GEO                        -196 ºC to +128 °C, 90 cycles/yr.

  Trans-Atmospheric Vehicle  -200 ºC to +260 ºC, cycles altitude
                             dependent and fairly minimum due to short
                             mission duration.

  Lunar Surface              -171 ºC to +111 ºC, 13 cycles/yr.

  Martian Surface            -143 ºC to +27 ºC, 356 cycles/yr.
  -------------------------- --------------------------------------------

Mars has four seasons as on Earth. The temperature varies, depending on
location, but generally during summer high temperature at the equator
ranges from -12 ºC to 4 °C, and during the winter polar temperature goes
as low as -126 °C. \[5\] Temperatures recorded by past missions are
shown in Table 8. Large changes in temperature in a particular location
are believed to be the source of the "wind," which creates [dust
devils](#dust_devil).

Figure 2 shows thermal blanket covering the Cassini
spacecraft.![](media/image2.jpeg){width="1.66875in"
height="2.564583333333333in"}

**Table 8.** Temperatures Recorded by Past Mars Missions \[6, 7\]

  ------------------------- ----------------- ----------------------------
  ***Mission***             ***Date***        ***Recorded min/ max
                                              Temperature^1^***

  Mariner 4                 July 1965         -133 °C to +27 °C

  Viking 1 Lander           July 1976         -94 °C to -17 ° C \[6\]

  Mars Pathfinder           July 1997         -80 °C to 0 °C \[6\]

  Spirit Rover              January 2004      -101 °C to +5 °C \[7\]
  ------------------------- ----------------- ----------------------------

**Note:**

1\. Temperatures from references converted to metric units for
consistency.

The values in Table 7 represent unmanaged environmental temperatures.
The values would be much less for electronics in a temperature-managed
area, perhaps by as much as half. The temperature requirements increase
towards these numbers when standard military specification requirements
are used for electronics, namely --55 °C to +125 °C.

PPEs surveyed for the temperature extremes and cycling reported
temperature numbers in the range of --50 °C to +50 °C for standard
missions and up to --165 °C to +93 °C for an external arm on a GOES
spacecraft. In these cases, 12 to 20 cycles were defined.

Reference \[3\] provides examples of typical operating temperature
ranges for mission allowable (actual use) acceptance and qualification
testing (Table 9) for several electrical subsystems. These temperatures
show that though the mission type may indicate rigorous environmental
conditions, spacecraft and subsystem design will tend to provide actual
conditions, which are much less severe, even with the margin included in
the qualification values.

**Table 9.** Example Operating Temperature Limits for Selected
Electrical Subsystems

  -------------------- ------------------ ---------- ------------ --------------- ---------- ------------ ------------ ---------- ------------
  ***Component***      ***Qualification                           ***Acceptance                           ***Mission              
                       (ºC)***                                    (ºC)***                                 (ºC)***                 

                       ***Min.***         ***to***   ***Max.***   ***Min.***      ***to***   ***Max.***   ***Min.***   ***to***   ***Max.***

  Power Control Unit   -23                to         +50          -13             to         +40          -8           to         +35

  Battery              -5                 to         +35          -5              to         +25          0            to         +20

  Solar Cells and      -180               to         +85          -170            to         +75          -165         to         +7
  Panels                                                                                                                          

  Heater Control       -35                to         +65          -25             to         +55          -20          to         +50
  Electronics                                                                                                                     

  S-Band Pre-Amp       -20                to         +55          -15             to         +43          -10          to         +45

  S-Band Output Mux    -15                to         +50          -5              to         +45          0            to         +4
  -------------------- ------------------ ---------- ------------ --------------- ---------- ------------ ------------ ---------- ------------

5\. []{#pressure .anchor}[Atmospheric Change and Vacuum]{.underline}

The flight hardware encounters changes in atmospheric pressure during
ground testing and launch and operates in a vacuum in space. Though
pressure changes and exposure to vacuum have been directly related, on
their own, to failure mechanisms (such as discharging between closely
spaced conductors during launch and oil-canning of sealed containers),
NASA focuses heavily on the combination of temperature and vacuum
together, and specifies operational and test requirements closely
linking the two. Table 10 shows the in-flight pressure expected for
flight hardware in various mission types \[2\].

**Table 10.** Pressure Conditions \[2\]

  ------------------- ---------------------- ------------------------------
  ***Mission Type***  ***Conditions***       ***Composition***

  Pressurized Module  517 Torr               21% oxygen^1^

  LEO                 10^-10^ Torr           

  GEO                 7.5 x10^14^ Torr       

  Trans-Atmospheric   760 Torr (sea level)   
  Vehicle             to 7.5 x 10^-14^ Torr  
                      (interplanetary)       

  Lunar Surface       10^-8^ to 10^-12^ Torr Gases (mainly neon, helium,
                                             and hydrogen) exist due to
                                             seismic activity but quickly
                                             dissipate due to lack of
                                             gravity and UV radiation.
                                             \[11\]

  Martian Surface     4.4 to 11.4 Torr       95% carbon dioxide, 3%
                                             nitrogen, and trace amounts of
                                             oxygen and water. \[12\]
  ------------------- ---------------------- ------------------------------

**Note:**

1\. Prior to EVA activity, the vestibule area's atmosphere is enriched
to 30% oxygen at 69 kPa.

6\. []{#humid .anchor}[Humidity]{.underline}

Humidity is considered for the "conditions of transportation, storage,
the orbiter cargo bay, and the orbiter manned spaces." Humidity is also
used as a specialty condition that accelerates certain failure
mechanisms in certain types of parts.

The specifications found to date, which explain operational requirements
or qualification test criteria for stresses due to humidity during
ground or space operations, are shown in Table 11.

**Table 11.** Requirements for Humidity \[2\]

  ------------------------------ --------------------------- -------------
  ***Requirement***              ***Location***              ***Value***

  Minimum and maximum in flight  Pressurized module          25% to 70%

  Assumed maximum for            Assembly, storage, and      100%
  uncontrolled environments      transport to launch         
                                 facility                    

  Maximum on launch pad          Payload                     ≤ 50%
  ------------------------------ --------------------------- -------------

7\. [Ultraviolet Radiation]{.underline}

The ultraviolet spectrum (specifically, the range 0.12 µm and 10 µm) is
singled out from the other wavelengths of sunlight irradiated on
spacecraft because it contains 99.5% of the total energy of all
electromagnetic radiation coming from the Sun. The energy intensity of
UV radiation depends on the constitution of the ambient media and is at
its highest in a vacuum. Equivalent Sun hours (ESH) per year is used to
compare the stress due to UV radiation between various mission types in
Table 12 \[2\]. The energy of UV radiation has been found to alter the
composition of materials such as polymers.

**Table 12.** Level of UV Radiation by Mission Profile \[2\]

  ----------------------------- -----------------------------------------
  ***Mission Type***            ***Conditions***

  Pressurized Module            None (shielded)

  LEO                           2220 to 5800 ESH/yr.^1^, energy of 118
                                W/m^2^

  GEO                           8760 ESH/yr., energy of 118 W/m^2^

  Trans-Atmospheric Vehicle     See LEO and GEO

  Lunar Surface                 8760 ESH/yr., energy of 1371 W/m^2^

  Martian Surface               1656 ESH/yr., energy of 649 W/m^2^
  ----------------------------- -----------------------------------------

**Note:**

1\. ESH = Equivalent Sun Hours

8\. []{#ionizing_rad .anchor}[Ionizing Particle Radiation]{.underline}

All types of spacecraft will be exposed to ionizing particle radiation
consisting of atomic and sub-atomic particles such as protons, heavy
ions, alpha particles, and electrons. The origin of these particles is
the Sun, via the solar wind, and they are either encountered directly
from the Sun's flux or in the Van Allen belts surrounding the Earth
where they are trapped in large densities. The number, flux, and
energies associated with a mission profile vary highly and are the
subject of a large part of the discipline of radiation physics and
engineering for space (see
<http://radhome.gsfc.nasa.gov/radhome/rpo.htm>). Information and
products related to radiation tolerance levels of 300 kRads and higher
are considered sensitive information and are subject to International
Traffic in Arms (ITAR) regulations. NASA programs were researched to
find current typical mission requirements and few representative
examples are shown below. Table 13 lists the results.

**Table 13.** Radiation Requirements for Current Missions

+----------------------+---------+-------+--------------+-------------+
| ***Project***        | ***TID  | ***S  | ***SEL***    | ***Disp     |
|                      | (kR     | EU*** |              | lacement*** |
|                      | ads)*** |       | ***(Me       |             |
|                      |         |       | V/mg/cm2)*** | *           |
|                      |         |       |              | **Damage*** |
+----------------------+---------+-------+--------------+-------------+
| GPM                  | 13.6    |       |              |             |
+----------------------+---------+-------+--------------+-------------+
| EOS-AURA             | 10      |       | 100          |             |
+----------------------+---------+-------+--------------+-------------+
| JWST                 | 50      |       |              |             |
+----------------------+---------+-------+--------------+-------------+
| AIM                  | 10      |       | 80           |             |
+----------------------+---------+-------+--------------+-------------+
| THEMIS               | 66      |       | 40           |             |
+----------------------+---------+-------+--------------+-------------+

9\. []{#atomic_oxygen .anchor}[Atomic Oxygen]{.underline}

Atomic (monatomic) oxygen is encountered in low-Earth orbit where the
last low-density residual amounts of our atmosphere reside. Monatomic
oxygen, created by UV excitation of the 0~2~ molecule, is highly
reactive with many space hardware materials and can cause erosion due to
impact with the fast moving spacecraft. Table 14 shows atomic oxygen
concern based on mission profile \[2\].

**Table 14.** Atomic Oxygen Concerns \[2\]

+---------------------------+------------------------------------------+
| ***Mission Profile***     | ***Level***                              |
+---------------------------+------------------------------------------+
| Pressurized Module        | N/A                                      |
+---------------------------+------------------------------------------+
| LEO                       | 10^11^ -- 10^12^ atoms/m^3^,             |
|                           |                                          |
|                           | atomic energy from 4.3 to 4.4 eV^1^      |
+---------------------------+------------------------------------------+
| GEO                       | Same as LEO                              |
+---------------------------+------------------------------------------+
| Trans-Atmospheric Vehicle | See LEO                                  |
+---------------------------+------------------------------------------+
| Lunar Surface             | N/A                                      |
+---------------------------+------------------------------------------+
| Martian Surface           | N/A                                      |
+---------------------------+------------------------------------------+

**Note:**

> 1\. To account for variations in the solar max, testing is done from
> 10^20^ to 10^22^ atoms/cm^2^/year.

10\. []{#gravity .anchor}[Gravity]{.underline}

Although we think of the space environment as generally uniform with
respect to gravity and at zero gravity, we know that there are
non-zero-gravity conditions in forward-moving spacecraft and on planet
surfaces. Zero gravity, or reduced value of gravity, has a significant
effect on mechanical systems such as spacecraft and instruments and
dominates our strategies for thermal management. It is important to
recognize that terrestrial applications leverage heavily from the heat
conduction through the ambient media of air and the "free" work that
gravity provides when it pulls cold air toward hot spots and lighter hot
air floats away (convection). A much reduced gravity environment makes
these passive thermal management removal methods unavailable. Table 15
shows gravity conditions for various mission types \[2\].

**Table 15.** Gravity \[2\]

  ---------------------------- ------------------------------------------
  ***Mission Type***           ***Conditions***

  Pressurized Modules          Same as LEO with exceptions due to thrust
                               conditions

  LEO                          \< 10^-6^ to 10^-3^ g

  GEO                          Same as LEO

  Trans-Atmospheric Vehicle    1 to 10^-6^g

  Lunar Surface                0.165 g

  Martian Surface              0.38 g
  ---------------------------- ------------------------------------------

11\. []{#charged_plasma .anchor}[Charged Plasma]{.underline}

Ionized particles reside in various levels of the Earth's orbit and can
create a host of problems when they interact with the spacecraft, which
can be both mechanically and electrically damaging. Careful
consideration of charging and degradation due to these charged particles
should be considered when designing spacecraft and subsystem grounding
schemes and during material selection for exposed surfaces. Table 16
shows charged plasma environment for various mission types \[2\].

**Table 16.** Charged Plasma Environment \[2\]

+-------------------------+--------------------------------------------+
| ***Mission Type***      | ***Conditions***                           |
+-------------------------+--------------------------------------------+
| Pressurized Module      | N/A                                        |
+-------------------------+--------------------------------------------+
| LEO                     | 3 x 10^4^ to 9 x 10^5^ cm^-3^, energies of |
|                         | 0.1 to 0.2 eV (high-density, low-energy    |
|                         | particles)                                 |
+-------------------------+--------------------------------------------+
| GEO                     | 0.24 to 1.12 cm^-3^, 120 to 295 keV        |
|                         |                                            |
|                         | (low-density, high-energy particles)       |
+-------------------------+--------------------------------------------+
| Trans-Atmospheric       | Will go through range of LEO and GEO       |
| Vehicle                 | (interplanetary travel space is considered |
|                         | the same as GEO for this category)         |
+-------------------------+--------------------------------------------+
| Lunar Surface           | Mostly charged particles from the solar    |
|                         | wind and galactic rays                     |
+-------------------------+--------------------------------------------+
| Martian Surface         | 10^3^ to 10^5^ atoms/cm^3^                 |
+-------------------------+--------------------------------------------+

12\. []{#combinef .anchor}[Combined Environments Tests]{.underline}

In order to qualify assembled instruments and spacecraft for flight,
combined environment tests that represent worst-case conditions expected
in actual mission life are used. GEVS specifies several different
combinations involving temperature, vacuum, and humidity (Table 13). The
level of vacuum required is 10^-5^ Torr. Test temperatures to be used
are defined by project use temperatures but must provide at least a ±10
ºC margin (with an exception in temperature-controlled areas). The
number of temperature cycles varies on the hardware level. Spacecraft
and payloads are required to have four thermal-vacuum cycles performed
with dwells at the temperature extremes for 24 hours. Instrument and
subsystems are required to have four thermal-vacuum cycles performed,
dwelling at temperature extremes for 12 hours. Eight cycles are required
at the component or unit level with dwell times of 4 hours. Table 17
shows GEVS test requirements for combined environments \[2\].

**Table 17.** GEVS Test Requirements for Combined
Environments![](media/image3.png){width="6.288888888888889in"
height="2.8319444444444444in"}

> T = Test, A = Analysis

Appendix A provides listing of environmental test requirements and test
conditions for various projects.

[References]{.underline}

\[1\] Operational Environments for Electrical Power Wiring on NASA Space
Systems, M. Stavnes, A. Hammoud, and R. Bercaw, NASA Lewis Research
Center, June 1994.

\[2\] General Environmental Verification Specification (GEVS) for STS
and ELV Payloads, Subsystems and Components,
<http://arioch.gsfc.nasa.gov/302/gevs-se/toc.htm>.

\[3\] The Influence of Space Environmental Factors on NASA Electrical,
Electronic and Electromechanical Parts Selection and Application, A.
Garrison and J. Barrows, December 1992.

\[4\] Outer Planets Program Environmental Requirements, August 1999,
<http://centauri.larc.nasa.gov/outerplanets/Envir_rqts.pdf>.

\[5\] The Adler Planetarium & Astronomy Museum,
[http://www.adlerplanetarium.org](http://www.adlerplanetarium.org/).

\[6\] Temperature on the Surface of Mars,
<http://hypertextbook.com/facts/2001/AlbertEydelman.shtml>.

\[7\] Mars Daily,
<http://www.marsdaily.com/2004/040109195713.ov9bww5y.html>.

\[8\] Detecting Dust Devils on Mars, June 24, 2004,
<http://www.jpl.nasa.gov/news/features.cfm?feature=519>.

\[9\] Martian Dust Devils Could Hamper Future Manned Missions, Keay
Davidson, *San Francisco Chronicle*, Jan. 12, 2004,
<http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2004/01/12/MNGK947BRU1.DTL>.

\[10\] ECSS Space Environmental Standard (ECSS E-10-04), March 2001,
http://www.estec.esa.nl/wmwww/WMA/

\[11\] Apollo 17 Lunar Atmospheric Composition Experiment,
<http://www.lpi.usra.edu/expmoon/Apollo17/A17_Experiments_LACE.html>.

\[12\] The Martian Atmosphere,
<http://www.starryskies.com/solar_system/mars_html/martian_atmosphere.html>.

[Appendix A]{.underline}

**Table 1a:** Environmental Conditions for Selected Flight Missions

<table style="width:100%;">
<colgroup>
<col style="width: 13%" />
<col style="width: 11%" />
<col style="width: 11%" />
<col style="width: 11%" />
<col style="width: 13%" />
<col style="width: 12%" />
<col style="width: 0%" />
<col style="width: 11%" />
<col style="width: 0%" />
<col style="width: 13%" />
</colgroup>
<tbody>
<tr class="odd">
<td><p> </p>
<p><strong><u>Project</u></strong></p></td>
<td><strong>GOES NOP (extreme high)</strong></td>
<td><strong>GOES NOP (nominal)</strong></td>
<td><strong>GOES NOP (extreme low)</strong></td>
<td><strong>Mars Exploration Rovers</strong></td>
<td colspan="2"><strong>Phoenix</strong></td>
<td><strong>AIM</strong></td>
<td colspan="2"><strong>THEMIS</strong></td>
</tr>
<tr class="even">
<td><p> </p>
<p><strong><u>Launch Date</u></strong></p></td>
<td> </td>
<td> </td>
<td> </td>
<td>6/10/2003 and 07/07/03</td>
<td colspan="2">Planned 2007</td>
<td> </td>
<td colspan="2"> </td>
</tr>
<tr class="odd">
<td><p> </p>
<p><strong><u>Website</u></strong></p></td>
<td>http://rsd.gsfc.nasa.gov/goes/</td>
<td>http://rsd.gsfc.nasa.gov/goes/</td>
<td>http://rsd.gsfc.nasa.gov/goes/</td>
<td>http://www.jpl.nasa.gov/missions/current/marsexplorationrovers.html</td>
<td colspan="2">http://phoenix.lpl.arizona.edu/</td>
<td>http://aim.hamptonu.edu/</td>
<td colspan="2"> </td>
</tr>
<tr class="even">
<td colspan="10"><p> </p>
<p><strong><u>Temperature Range (Parts) degrees C</u></strong></p></td>
</tr>
<tr class="odd">
<td></td>
<td>+90</td>
<td>-20 to +50</td>
<td>-193 (80K)</td>
<td>-120 to 85C</td>
<td colspan="2">-120C to 85C (Qual hardware)</td>
<td>-45 to +45</td>
<td colspan="2">-50 to +65</td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>Duration of Mission (yrs)</u></strong></td>
</tr>
<tr class="odd">
<td></td>
<td> </td>
<td>10</td>
<td> </td>
<td>0.26</td>
<td colspan="2"> </td>
<td>3</td>
<td colspan="2">2</td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>Vibration Random</u></strong></td>
</tr>
<tr class="odd">
<td><strong><u>Freq. Range Hz</u></strong></td>
<td> </td>
<td>20 - 2000</td>
<td> </td>
<td>MEFL + 3dB</td>
<td> </td>
<td colspan="3"> </td>
<td>20 - 2000</td>
</tr>
<tr class="even">
<td><strong><u>Total G's</u></strong></td>
<td> </td>
<td>12.3</td>
<td> </td>
<td> </td>
<td> </td>
<td colspan="3">15.8</td>
<td>8.7</td>
</tr>
<tr class="odd">
<td colspan="10"><strong><u>Vibration Sine</u></strong></td>
</tr>
<tr class="even">
<td><strong><u>Freq. Range Hz</u></strong></td>
<td> </td>
<td>5 - 80</td>
<td> </td>
<td> </td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
<tr class="odd">
<td><p><strong><u> </u></strong></p>
<p><strong><u>Total G's</u></strong></p></td>
<td> </td>
<td>10</td>
<td> </td>
<td> </td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>Shock</u></strong></td>
</tr>
<tr class="odd">
<td><strong><u>F in Hz</u></strong></td>
<td> </td>
<td> </td>
<td> </td>
<td>MEFL + 3dB</td>
<td> </td>
<td colspan="3">100 &amp; 1000</td>
<td> </td>
</tr>
<tr class="even">
<td><strong><u>Max. G</u></strong></td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
<td colspan="3">50 &amp; 3000</td>
<td> </td>
</tr>
<tr class="odd">
<td colspan="10"><strong><u>Temp. Cycle</u></strong></td>
</tr>
<tr class="even">
<td><strong><u>Range of Temp. (spacecraft or payload
level)</u></strong></td>
<td>-165 to +93</td>
<td>-20 to +60</td>
<td>-165 to +93</td>
<td>-120C to 85C</td>
<td></td>
<td colspan="3">-50 to +50</td>
<td></td>
</tr>
<tr class="odd">
<td><strong><u>Cycle Number (testing)</u></strong></td>
<td>12</td>
<td>12</td>
<td>12</td>
<td>3X number of mission/ground</td>
<td></td>
<td colspan="3">8</td>
<td></td>
</tr>
<tr class="even">
<td><strong><u>Max Number Cycles (miss life)</u></strong></td>
<td>20</td>
<td>20</td>
<td>20</td>
<td>300 cycles, 90 days</td>
<td></td>
<td colspan="3"></td>
<td></td>
</tr>
</tbody>
</table>

**Table 1b.** Environmental Conditions for Selected Missions

<table style="width:100%;">
<colgroup>
<col style="width: 13%" />
<col style="width: 11%" />
<col style="width: 11%" />
<col style="width: 11%" />
<col style="width: 13%" />
<col style="width: 12%" />
<col style="width: 0%" />
<col style="width: 11%" />
<col style="width: 0%" />
<col style="width: 13%" />
</colgroup>
<tbody>
<tr class="odd">
<td><p> </p>
<p><strong><u>Project</u></strong></p></td>
<td><strong>GOES NOP (extreme high)</strong></td>
<td><strong>GOES NOP (nominal)</strong></td>
<td><strong>GOES NOP (extreme low)</strong></td>
<td><strong>Mars Exploration Rovers</strong></td>
<td colspan="2"><strong>Phoenix</strong></td>
<td><strong>AIM</strong></td>
<td colspan="2"><strong>THEMIS</strong></td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>Radiation (w/o design
margin)</u></strong></td>
</tr>
<tr class="odd">
<td><strong><u>TID kRads</u></strong></td>
<td></td>
<td>1M</td>
<td></td>
<td></td>
<td></td>
<td colspan="3">10</td>
<td>66</td>
</tr>
<tr class="even">
<td><strong><u>SEL in MeV/mg/cm2</u></strong></td>
<td></td>
<td></td>
<td></td>
<td>50</td>
<td></td>
<td colspan="3">80</td>
<td>40</td>
</tr>
<tr class="odd">
<td colspan="10"><strong><u>Pressure (Torr)</u></strong></td>
</tr>
<tr class="even">
<td></td>
<td></td>
<td></td>
<td></td>
<td>7.6</td>
<td></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="odd">
<td colspan="10"><strong><u>Environmental Condition</u></strong></td>
</tr>
<tr class="even">
<td><strong><u>Temp</u></strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="odd">
<td><p><strong><u> </u></strong></p>
<p><strong><u>Humidity</u></strong></p></td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>POC</u></strong></td>
</tr>
<tr class="odd">
<td> </td>
<td>G. Kiernan</td>
<td>G. Kiernan</td>
<td>G. Kiernan</td>
<td>R. Ramesham</td>
<td> </td>
<td colspan="3">J. Osche</td>
<td>J. Osche</td>
</tr>
</tbody>
</table>

**Table 2a.** Environmental Conditions for Selected Missions

<table style="width:100%;">
<colgroup>
<col style="width: 13%" />
<col style="width: 11%" />
<col style="width: 8%" />
<col style="width: 2%" />
<col style="width: 11%" />
<col style="width: 13%" />
<col style="width: 12%" />
<col style="width: 0%" />
<col style="width: 11%" />
<col style="width: 0%" />
<col style="width: 13%" />
</colgroup>
<tbody>
<tr class="odd">
<td><p> </p>
<p><strong><u>Project</u></strong></p></td>
<td><strong>DAWN</strong></td>
<td colspan="2"><strong>EOS-AURA</strong></td>
<td><strong>GPM</strong></td>
<td><strong>LTMPF (Low Temperature Microgravity Physics
Facility)</strong></td>
<td colspan="2"><strong>Outer Planets Program, Pluto, LaRC</strong></td>
<td><strong>Outer Planets Program, Solar Probe, LaRC</strong></td>
<td colspan="2"><strong>Galaxy Evolution Explorer</strong></td>
</tr>
<tr class="even">
<td><p> </p>
<p><strong><u>Launch Date</u></strong></p></td>
<td>Planned 2006</td>
<td colspan="2"> </td>
<td> </td>
<td> </td>
<td colspan="2"> </td>
<td> </td>
<td colspan="2">4/28/2003</td>
</tr>
<tr class="odd">
<td><p> </p>
<p><strong><u>Website</u></strong></p></td>
<td>http://dawn.jpl.nasa.gov</td>
<td colspan="2">http://aura.gsfc.nasa.gov</td>
<td>http://gpm.gsfc.nasa.gov</td>
<td>http://ltmpf.jpl.nasa.gov</td>
<td colspan="2"> </td>
<td> </td>
<td colspan="2">http://www.jpl.nasa.gov/missions/current/galex.html</td>
</tr>
<tr class="even">
<td colspan="11"><p> </p>
<p><strong><u>Temperature Range (Parts) degrees C</u></strong></p></td>
</tr>
<tr class="odd">
<td></td>
<td>-79C to +170C</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td colspan="2"></td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="11"><strong><u>Duration of Mission (yrs)</u></strong></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="2">The Dawn mission will launch in May 2006. It will study
Vesta beginning in July 2010, and Ceres beginning in August 2014.</td>
<td colspan="2"></td>
<td></td>
<td colspan="2"></td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="11"><strong><u>Vibration Random</u></strong></td>
</tr>
<tr class="odd">
<td><strong><u>Freq. Range Hz</u></strong></td>
<td>10-20</td>
<td colspan="2">20 - 2000</td>
<td> </td>
<td> </td>
<td>20 - 2000</td>
<td colspan="3">20 - 2000</td>
<td> </td>
</tr>
<tr class="even">
<td><strong><u>Total G's</u></strong></td>
<td>0.0322 g2/Hz Qual/PF level</td>
<td colspan="2">8.7</td>
<td>9.5</td>
<td> </td>
<td>16.7</td>
<td colspan="3">16.7</td>
<td> </td>
</tr>
</tbody>
</table>

**Table 2b.** Environmental Conditions for Selected Missions

<table style="width:100%;">
<colgroup>
<col style="width: 13%" />
<col style="width: 11%" />
<col style="width: 11%" />
<col style="width: 11%" />
<col style="width: 13%" />
<col style="width: 12%" />
<col style="width: 0%" />
<col style="width: 11%" />
<col style="width: 0%" />
<col style="width: 13%" />
</colgroup>
<tbody>
<tr class="odd">
<td><p> </p>
<p><strong><u>Project</u></strong></p></td>
<td><strong>DAWN</strong></td>
<td><strong>EOS-AURA</strong></td>
<td><strong>GPM</strong></td>
<td><strong>LTMPF (Low Temperature Microgravity Physics
Facility)</strong></td>
<td colspan="2"><strong>Outer Planets Program, Pluto, LaRC</strong></td>
<td><strong>Outer Planets Program, Solar Probe, LaRC</strong></td>
<td colspan="2"><strong>Galaxy Evolution Explorer</strong></td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>Vibration Sine</u></strong></td>
</tr>
<tr class="odd">
<td><strong><u>Freq. Range Hz</u></strong></td>
<td> </td>
<td> </td>
<td>5 - 50</td>
<td>2.5 G (5-30Hz) and 2.0G (30-100Hz)</td>
<td>5 - 100</td>
<td colspan="3">5 - 100</td>
<td> </td>
</tr>
<tr class="even">
<td><p><strong><u> </u></strong></p>
<p><strong><u>Total G's</u></strong></p></td>
<td> </td>
<td> </td>
<td> </td>
<td>9.1 Grms</td>
<td>7.5</td>
<td colspan="3">7.5</td>
<td> </td>
</tr>
<tr class="odd">
<td colspan="10"><strong><u>Shock</u></strong></td>
</tr>
<tr class="even">
<td><strong><u>F in Hz</u></strong></td>
<td>100Hz</td>
<td>100 &amp; 3000</td>
<td>1500-3000</td>
<td>None</td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
<tr class="odd">
<td><strong><u>Max. G</u></strong></td>
<td>15 g</td>
<td>57 &amp; 5740</td>
<td>4100</td>
<td> </td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>Temp. Cycle</u></strong></td>
</tr>
<tr class="odd">
<td><strong><u>Range of Temp. (spacecraft or payload
level)</u></strong></td>
<td>-35 to 75C</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="even">
<td><strong><u>Cycle Number (testing)</u></strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="odd">
<td><strong><u>Max Number Cycles (miss life)</u></strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>Radiation (w/o design
margin)</u></strong></td>
</tr>
<tr class="odd">
<td><strong><u>TID kRads</u></strong></td>
<td>0.3 Krads 9based on 6 months with 100 mils shielding and RDF=2</td>
<td>10</td>
<td>13.6</td>
<td> </td>
<td>65</td>
<td colspan="3">25</td>
<td>5krad(Si) with RDM=2</td>
</tr>
<tr class="even">
<td><strong><u>SEL in MeV/mg/cm2</u></strong></td>
<td> </td>
<td>100</td>
<td> </td>
<td> </td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
<tr class="odd">
<td colspan="10"><strong><u>Pressure (Torr)</u></strong></td>
</tr>
<tr class="even">
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="odd">
<td colspan="10"><strong><u>Environmental Condition</u></strong></td>
</tr>
<tr class="even">
<td><strong><u>Temp</u></strong></td>
<td>-79C to +170C</td>
<td> </td>
<td> </td>
<td>-35 to 75C</td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
<tr class="odd">
<td><p><strong><u> </u></strong></p>
<p><strong><u>Humidity</u></strong></p></td>
<td>&gt;or = 30% or &lt;or = 70%</td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
<tr class="even">
<td colspan="10"><strong><u>POC</u></strong></td>
</tr>
<tr class="odd">
<td> </td>
<td> </td>
<td>T. King</td>
<td>R. Williams</td>
<td> </td>
<td> </td>
<td colspan="3"> </td>
<td> </td>
</tr>
</tbody>
</table>