A thin membrane covering the open side of a meteoroid capture cell causes an impacting meteoroid to disintegrate as it penetrates the membrane. The capture cell then contains and holds the meteoroid particles for later analysis

High, R. W.

Zook, H. A.

English

NASA Technical Reports Server

United States Patent t 191 
Zook et al. 
[541 METEOROID CAPTURE CELL 
[75] 
[ 731 Assignee: The United States of America as 
CONSTRUCTION 
Inventors: Herbert A. Zook; Richard W. High, 
both of Houston, Tex. 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[22] Filed: Mar. 5, 1974 
[21] Appl. No.: 448,320 
[52] U.S. Cl .............................. 731425.2; 731170 R 
731432 R 
[SI] Int. CI .* ............................................ GOlN 1/00 
Field of Search ........... 73/11, 12, 170 R, 425.2, 
731432 R, 432 PS, 425,28 
[58] 
V 
a. 
[111 3,971,256 
[451 July 27, 1976 
[561 References Cited 
UNITED STATES PATENTS 
3,446,068 511969 Slattery et al ....................... 73/12 X 
3,678,759 711972 Schneeberger .................. 731432 PS 
3,842,656 1011974 Di Battista ................... 731432 PS X 
Primary Examiner-Richard C. Queisser 
Assistant Examiner-John S. Appleman 
Attorney, Agent, or Firm-Carl 0. McClenny; John R. 
Manning; Marvin F. Matthews 
t571 ABSTRACT 
A thin membrane covering the open side of a meteor- 
oid capture cell causes an impacting meteoroid to dis- 
integrate as it penetrates the membrane. The capture 
cell then contains and holds the meteoroid particles 
for later analysis. 
3 Claims, 3 Drawing Figures 
https://ntrs.nasa.gov/search.jsp?R=19760023043 2020-03-20T02:26:35+00:00Z
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a. 
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Fig 1 
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3,97 1.256 
1 
METEOROID CAPTURE CELL CONSTRUCTION 
ORIGIN OF THE INVENTION 
The invention described herein was made by employ- 
ees of the U.S. Government and may be manufactured 
and used by or for the Government of the United States 
of America for governmental purposes without the 
payment of any royalties thereon or therefor. 
BACKGROUND OF THE INVENTION 
The invention relates to meteoroid capturing devices 
and is directed more particularly to one employing a 
cavity (or cell) covered by a thin membrane. 
There arc three ways in which meteoroids have been 
studied and analyzed in the past. One way has been to 
analyze meteorites, Le., the remnants that one finds on 
the ground, of meteoroids which have passed through 
the atmosphere. There are reasons to believe, however, 
that only a special class of meteoroids do not burn 
completely upon their entry into the atmosphere, 
thereby leaving a remnant (meteorite) which can be 
analyzed. Hence, the analysis of meteorites may give a 
distorted view of the general composition of meteor- 
oids. Another technique is to analyze the spectra of 
meteor trails, the fiery trail made by an incoming mete- 
oroid. However, this technique is presently beset with 
considerable difficulty and uncertainty. 
A third technique, developed relatively recently, 
works as follows: A set of meteoroid interaction sur- 
faces, shaped somewhat like a semi-open venetian 
blind, is launched into space. Behind the interaction 
surfaces, a strong electric field is applied to accelerate 
positive ions toward a current measuring device. When 
a meteoroid strikes one of the interaction surfaces, part 
of it is spewed off as an ionized vapor. The positive ions 
in this ionized vapor are then accelerated toward the 
charge collector. The ratio of electric charge to mass of 
the various species of positive ions determines their 
respective times of arrival relative to the detection of 
electrons near the interaction surfaces. This technique 
suffers from problems similar to those encountered in 
analyzing meteor trails. Namely, the probability of 
ionization of the various species of elements under 
hypervelocity impact conditions is not well known and 
therefore the original meteoroid composition cannot 
be accurately determined. 
SUMMARY OF THE INVENTION 
Meteoroids are captured in the following manner: 
Arrays of cube or other shaped cells of very pure mate- 
rial are constructed for deployment from a spacecraft. 
One side of the cell is left open over which a thin mem- 
brane, preferably of the same material as the cells, is 
affixed. A meteoroid then strikes the thin membrane 
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25 
30 
35 
40 
45 
50 
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and enters the cell. Because of the very high velocity of 
the meteoroid, the thin membrane causes the meteor- 
oid to completely shatter or disintegrate. The mem- 
brane is, however, thin enough to allow penetration of 
all the meteoroid particles which lie in the mass range 60 
for which the cell is designed. The rest of the cell is 
manufactured thick enough to contain the high velocity 
remnants of the meteoroid as well as most of the vapor 
that may be created due to impact heating. The con- 
tents of the cell are later analyzed for element and 65 
chemical content. 
Meteoroids collected and analyzed in this fashion 
should not suffer from the same selection effects of 
2 
picking out a specialized class as do meteorite studies, 
meteor studies, or impact ionization studies. The tech- 
nique taught by this invention enables one to bring the 
meteoroid into the lab for whatever analysis is desired, 
whereas analysis of meteors, for example, can only be 
done spectroscopically (except for very large bolides 
where high-flying airplanes may take samples of the air 
that includes some meteoritic material). 
I t  is an object of the invention to provide a meteoroid 
capture cell, for capturing and containing meteoroids, 
wherein minimum contamination of the meteoroid 
particles by the cell is achieved. 
It is another object of the invention to provide a 
membrane, or cell covering, which will cause disinte- 
gration of an impacting meteoroid while allowing a 
large percentage of the selected particles to penetrate 
the membrane and be captured within the cells. 
It is a further object of the invention to provide a cell 
wall of a thickness and material which will provide 
sufficient strength to contain or hold a disintegrating 
meteoroid while minimizing the cell weight. 
It is still another object of the invention to provide a 
meteoroid capture cell which will withstand all the 
environmental conditions to which a spacecraft may be 
exposed. 
Other objects and advantages of the invention will 
become apparent from the description and the drawing 
of a meteoroid capture cell embodying the invention. 
BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 is an isometric drawing of a single meteoroid 
FIG. 2 illustrates the process of meteoroid breakup 
FIG. 3 illustrates an array of capture cells. 
capture cell with its membrane displaced. 
and capture by a cell. 
DESCRIPTION OF THE PREFERRED 
EMBODIMENT 
Referring now to FIG. 1, reference numeral 10 desig- 
nates a meteoroid capture having an open side 12. A 
thin membrane 14, preferably of the same material as 
the capture cell 10, covers the open side 12 of the 
capture cell 10. When a meteoroid of the preferred size 
range impacts the membrane 14, two reactions occur. 
First, the membrane 14 is penetrated by the meteoroid, 
and second, the meteoroid disintegrates under the col- 
lision-induced shock pressure. The particles of the 
disintegrated meteoroid are thus captured within the 
cavity of the capture cell 10. A relatively small portion 
of the impacting meteoroid is back-splattered from the 
membrane 14 and is lost. FIG. 2 illustrates the process 
of meteoroid capture by a cell wherein a meteoroid 16 
having a velocity v strikes the membrane 14, where- 
upon the membrane 14 is penetrated at 18 and the 
meteoroid 16 shatters upon impact. The meteoroid 
particles 20 are embedded in the inner walls of the 
capture cell 10 where they remain until removed for 
analysis. 
FIG. 3 depicts an array 30 of capture cells 10 having 
a common membrane 14. 
Meteoroids are of sizes ranging from less than 
gm to approximately IO+'* gm (above which size they 
may be called asteroids or comets). Although the in- 
vention described does not depend upon meteoroid 
size, the physical size of the meteoroid capturing device 
will depend upon the size meteoroid one desires to 
capture. There are some advantages, in terms of size 
and cost, to try to capture fairly small (-lo+ gm) 
3,97 1,256 
3 4 
meteoroids rather than larger ones. Although the in- tainer was made of 1.27 mm 1,100 aluminum having 
vention is not restricted to capturing small meteoroids, cell walls of 0.76 mm 1,100 aluminum. The cells were 
present design efforts are directed toward trying to lined with 0.9999 purity aluminum foil and covered 
capture meteoroids in the mass range IO-’to gm. with a membrane of the same material. A later proto- 
Meteoroids strike the upper atmosphere of the earth 5 type was made with high-purity polyethylene cells. 
with velocities ranging from 1 1  to 72 km/sec with an Polyethylene or other synthetic material cells are pre- 
average velocity of about 19 km/sec. The impacting ferred over aluminum or other metals for at  least two 
velocities relative to an earth-orbiting or to an inter- reasons: ( 1 ) Polyethylene or other synthetic materials 
planetary spacecraft would be distributed differently can be obtained in extremely pure form; and, ( 2 )  if a 
from those entering the upper atmosphere. However, l o  metal is used, that metal and its associated impurities 
nearly all of the meteoroids striking a spacecraft, re- usually cannot easily be separated from the meteoroid 
gardless of its trajectory, would have velocities in the debris in the analysis. 
hypervelocity range. The term hypervelocity is defined The procedure involved in operating the invention is 
to be that velocity (about 3 or 4 km/sec) above which to expose an array of cells to the space environment so 
a meteoroid will completely shatter upon striking an- I 5  that meteoroids can strike the membranes covering the 
other object. cells. Before injection into and deployment in space, 
Various techniques for chemical analysis of the mete- the cells must be packaged in some suitable manner 
oroid particles may be used, such as neutron activation, which does not require too much weight and volume. 
electron microprobe, emission spectroscopy, and so This is also true upon return from space. They could be 
on. *’ initially rolled up, for example, or folded accordian-like 
As an example of cell size, suppose one wished to and then deployed by unrolling or unfolding. It is also 
capture meteoroids in the mass range of possible that the transport volume could be further 
gm. With an assumed meteoroid density of 2 gm/cm3, decreased by making the individual cells collapsible. 
to 
the corresponding projectile diameters would range 
from about 50 to 500 microns. A 10 micron thick mem- 
brane (thickness is somewhat dependent on membrane 
composition) would allow penetration by practically all 
of a 50 micron projectile. It would also break up the 
500 micron projectile sufficiently so that the rest of the 3o 
cell being used as a catcher need not be unduly thick 
and heavy to contain the debris. Membrane and cell 
wall thickness should be optimized for the meteoroid 
mass of particular interest. 
cells are required to construct a practical experiment. 
To have a 65% probability of capturing a gm or 
larger meteoroid, one should expose about 0.56 square 
meters of collecting area for 1 year. More precisely, 
any combination of area-time products that gives 0.56 4o 
m2 - years of experiment exposure to space will pro- 
duce a reasonable probability of capturing a meteoroid 
that has at least gm mass. Hence, for most experi- 
25 
Because meteoroids do not arrive very often, many 35 
We claim: 
1. A meteoroid capture cell comprising: 
a. A housing for receiving and restraining particles 
from shattered meteoroids of a pre-selected size 
class, said housing being constructed entirely of 
one chemical substance having a purity of at least 
0.9999 and having one open side for receiving 
therethrough said particles and wherein the thick- 
ness of said housing substance is resistant to com- 
plete penetration by said particles; and, 
b. A membrane comprised of the same chemical 
substance as said housing affixed to and covering 
the open side of said housing wherein the thickness 
of said membrane is responsive to penetration by a 
meteoroid of said pre-selected size class striking 
said membrane while causing complete shattering 
of said meteoroid as said meteoroid penetrates said 
mem brane. 
2. The capture cell of claim 1 wherein said chemical 
mental uses of the design described above, a very large 
number of cells are required. One prototype (see FIG. 45 
3) utilized an “egg crate” design having individual cells 
about 6.4 mm on a side with 64 cells in each unit of the 
design. The “unit” was designed to be one of many to 
substance is polyethylene. 
3. The capture cell of claim 1 wherein said chemical 
substance is aluminum, the thickness of said housing 
walls is approximately I .27 mm and the thickness of 
said membrane is approximately 0.025 mm. 
be structurally held in a lightweight frame. The con- * * * * *  
50 
5 5  
65 


Meteoroid capture cell construction

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