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Deep Sky Black Properties
NOTE: Deep Sky Black properties below represent both as
tested information as well as expected performances based on testing conducted
on earlier variations of "similar" products, including the product
which was known as Martin Black (MB). All testing by Equinox Interscience to
date indicate that where we specify an expected result, that the expectations
are quite reasonable. Testing to date has shown Deep Sky Black to meet or
exceed expectations for performance.
Electrostatic Charge – Deep Sky Black surface does not support
electrical potential higher than approximately 200 volts. Above this level,
the charge leaks off through the coating with no change to the surface
properties. This is typical of anodized surfaces of this type.
Vibration – It is expected that the Deep Sky Black surface
could release some particles in "extreme" vibration environments.
Again, this is typical of anodized surfaces of this type and these extreme
environments are typically harsher than the typical launch vehicle spectrum.
The particles in this case can be removed from the surface by a cleaning
process. Test results indicate that the cleaning process eliminates particles
to the background level of particles collected at random with a sample tape.
MB surface had been subjected to vibration tests, both mechanical and
acoustical, early in its development. The mechanical vibration was 10 g
sinusoidal, with a sweep rate of 2 minutes per octave; 20 g root mean square
(RMS) Shuttle spectrum for 18 minutes.
There was no mechanical or optical deterioration. An 18 minute acoustic
vibration test at 145-dB Shuttle Spectrum was also conducted with no mechanical
or optical deterioration.
Temperature and Vacuum – It is expected that Deep Sky Black
surface will show no deterioration or degradation after exposure to the
following environments:
- Temperatures up to 450 deg C at 10 to the minus 5
Torr
- Simulated sunlight (including ultraviolet) exposure for 500
hours at 10 to the minus 5 torr
Cryogenic Test - Test were conducted on MB back in July of
1970 at the Electronics Laboratory, San Diego, Ca. Hemispherical emittance
(absorbance) tests were conducted at 4 and 77 K. In the far-infrared region (7
to 120 m m), emittance was 0.985 or better.
Handling – Abrasion by touching, wiping, or dropping articles
on the surface modifies the surface structure and may reduce the absorptivity
or Lambertian character of the surface. The surface is also subject to
contamination from dust, airborne particles, and outgassed organic molecules or
clusters, and this contamination will change the optical properties of the
surface. It is important, therefore, to handle parts with Deep Sky Black
surfaces with the care afforded "all" optical surfaces.
Outgassing – It is expected that Deep Sky Black passes
NASA SP-R-0022A specifications (General Specification, Vacuum Stability
Requirements of Polymeric Material for Spacecraft Applications, 9 September
74). It is found that most anodize surfaces of this type do well in testing
for this characteristic. Early studies from the literature on the outgassing
of MB are available. Oak Ridge National Laboratory (C.M. Egert and J.A.
Basford: "Vacuum Outgassing from Diffuse-Absorptive Baffle
Materials." Proceedings of the SPIE, Vol 1330, 1990, pp 178-185) and
Goddard Space Flight Center (T. Heslin, and R. Hunkeler: "Outgassing
Rates of Various Aluminum Anodizes." Materials Technology Report,
MTR No. 755-011, Goddard Space Flight Center. April 1975). Studies
indicate that water is the primary component, followed by two other elements of
air – nitrogen and oxygen. Between 240 C and 800 C carbon dioxide, sulfur
dioxide, sulfur monoxide, and two unidentified species (34 and 78 atomic mass
units) had been detected.
Baffle Edge Application – In the optical design of most
sunshades, baffles are used to prevent stray light reflected by the interior
surfaces of the shade from reaching the optical system entrance pupil directly.
However, it is impossible to eliminate all light reflected by the edges of the
baffles themselves; thus these edges must be designed to reflect the minimum
light possible. Equinox Interscience works with your design team to optimize
the baffle engineering approach.
Deep Sky Spaceship Black – Deep Sky Spaceship Black provides a more
durable surface. Deep Sky Spaceship Black also has been shown to be less
susceptible to reaction with atomic oxygen. The Spaceship Black variation in
the process has also shown a somewhat improved optical performance in the near-
and middle- IR. Reflectances from about 37% at 2,3 µm to about 25% and from
about 15% at 5.5 µm to about 3.5% has been demonstrated and verified in recent
characterizations at Raytheon Santa Barbera Research Center. The performance
in the visible region of the spectrum is maintained. From historical
information, we know that the so-called "enhanced" version of MB was
subjected to atomic oxygen testing. The results were documented in the
Proceedings of the SPIE, Vol 511, 1984, pp 24-30.
| Process and Material Spec Numbers for Deep Sky
Black: |
| Process: | EIP10021A-2 Rev C (October 31, 2000) |
| Material: | EIM10021A-2 Rev A (August 1, 1997) |
| Equipment: | EIE10021A –2 Rev A (August 1, 1997) |
| |
Process and Material Spec Numbers for Deep Sky
Spaceship Black: |
| Process: | EIP10022A-2 Rev C (October 31, 2000) |
| Material: | EIM10022A-2 Rev A (August 1, 1997) |
| Equipment: | EIE10022A-2 Rev A (August 1, 1997) |
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