Space from 100 to 1000 km. is not a perfect vacu~~, nor is it
isothermal. At about 100 km. the me!U1 mole:;ular weight of the at-
mosphere undergoes a marked change, where 02 becomes dissociated by
sunlight into atomic oxygen (see Fig. 2). Up to about 100 km.
the temperature profile varies between about ZOOoK. and 300 oK. Above
100 km. the temperature undergoes a steady increase to 1000 o K. or
more. Fig. 3 shows how the relative density of the atmosphere
varies with height up to a height of 1000 km. Above 200 km. the
density is sensitive to the asymptotic high-level temperature, too,
whi.<;;h varies with t"hL~ solar c.ycle and geompgneti~ activity.
If the earth were a perfect sphere and if there were no atmospheric
drag, satellites in orbit around our planet would behave according to
Kepler I s Laws of planetary orhi ts aroulld the sun. Table 4 h derived
from Kepler's third law. The relationship between the ?eriod in
seconds (p) al:d the mean distance in centimeters (r) is '3xpressed by:
2
P
2 3 -19 3
4 IT r ~ 0.9906 x 10 r= --_._-
G M fj
where G, the gravitational constant, is 6.668 x 10- 8 cbs and Mfj'
the mass of the earth, is S 977 x 10 27 grams. The mean speed in
orbit (the last column) is obtained from the relationsJ-d.p:
s = 271r 10
= 1,996 x 10
)1 rr
By applying Kepler's third law we have imnli~d the ~a]idity of
Kepler's first two Lws with respect to satellite orhits; i.e.: that
~Iltellites move about the l'arth in elliptical orhits with the center
of the (,sl,th at one focus of the ellipse; and that the radius vector
sl-'ept out by the satell i te with respect to the center of the earth
sweeps out equal areas in equal times.
The angular veJoc.ity of a satellite, (proportional to the re-
ciprocal of the period), dl'cre,3.ses R~l the radius of the orbi t
279
Space from 100 to 1000 km. is not a perfect vacuum, nor is it
isothermal. At about 100 km. the me'U1 mole;;ular weight of the at-
mosphere undergoes a marked change, where 02 becomes dissociated by
sunlight into atomic oxygen (see Fig. 2). Up to about 100 km.
the temperature profile varies between about 200 o K. and 300 o K. Above
100 km. the temperature undergoes a steady increase to 1000 o K. or
more. Fig. J shows how the relative density of the atmosphere
varies with height up to a height of 1000 km. Above 200 km. the
density is sensitive to the asymptotic high-level temperature, too,
whidl varies w.ith the solar .:yc)e 8. Tl d geoml'gnetic activity.
If the earth were a perfect sphere and if there were no atmospheric
drag, satellites in orbit around our planet would behave according to
Kl'plcr's L~.ws of planetary orhits arou,ld the sun. Table 4 i;, derived
from Kep!er's third law, The relat]onship between the period in
!::econds (p) :;,:d the mean distance in centimeters (r) is '~xpressed by:
2
P
2 3 -19 3
4 n r = 0.9906 x 10 r
G MIi
-8
where G, the gravitational constant, is 6.668 x 10 cbs and Mi'
27
the mass of the earth, is 5 977 x 10 grams. The mean speed in
orbit (the last column) is obtained from the relatioIlshj.p:
S = 2nr = 1,996 x 10 10
-----
J1 rr
By applying Kcplcr's third law we have iml)I i ',d the ·,al iui ty of
Kepler's first two l~lI's with respect to sBLolliLe orbits; Le.: that
~Iltellites move about the ('arth in elliptical orhits with the center
of the earth at one focus of the ellipse; and that the radius vector
s~lept out by the satell i te wi til respect to the center of the earth
sweeps out equal ar",as in equal times.
The angulbr veJocity of a satellite, (proportional to the re-
ciprocal of the period), decreases fl~, th(~ radius of thc orbi t
279