NASA Technical Reports Server (NTRS) 19620001224: THE TIROS SATELLITES

10. THE TIROS SATELLITES

By W. G. Stroud, Chief, Aeronomy and Meteorology Division, Goddard Space Flight Center, National

Aeronautics and Space Administration

This Workshop provides the opportunity to
evaluate the performance of the Tiros meteoro-
logical satellite system as part of the NASA
studies of the atmosphere and its motions. In
addition, the three satellites launched have
varied in degree of success. The usual difficul-
ties that an experimental physicist or meteorolo-
gist may have in conducting atmospheric experi-
ments have been encountered. However, these
have been exaggerated by the unusual labora-
tory (space) in which the experiments are being
conducted.

There has been no question for some time of
the value of meteorological satellites. But the
technology of the launch vehicles, the telemetry
problem, that is, the problem of communicating
the data from the satellite to the ground, and
all the other practical considerations, including
funds, have only recently permitted the reali-
zation of the desires of meteorologists and geo-
physicists iu bring (lie entire earth under
observation.

The point of view taken by NASA is that
Tiros represents a series of experiments rather
than a purely operational tool or the final an-
swer in the problem of making measurements
from outside the atmosphere. A close analysis
of the infrared and reflected solar radiation
data obtained by the Tiros satellites reveals the
experimental nature. Not only does it take
time to receive the data from the satellite but it

also takes time to interpret these data in terms
of the atmospheric phenomena.

The experimental Tiros system can really be
broken down into four major elements: The
launch vehicle; the spacecraft or satellite; the
data acquisition, that is, the problems of acquir-
ing the data from the satellite by the ground
stations; and the data utilization, that is, the
procedures by which the data are used. This
paper is concerned with only the first three of
these elements.

The launch vehicle. — The Thor-Delta used to
launch the satellite is a three-stage vehicle:
liquid, liquid, and solid; that is, the first two
stages are liquid and the third stage is solid. It
has been used to launch Tiros I, II, and III.
The Tiros I launch vehicle was slightly differ-
ent in terms of guidance and sequencing, but it
had the same propulsive units. These three
vehicles have placed the satellites in nominally

ods and roughly 48° inclination. This means
that the satellite latitude excursion is between
48° north and 48° south latitudes, correspond-
ing roughly to the limits of the globe brought
under observation.

Figure 10-1 shows the Thor booster being
inserted in the launch stand prior to the launch-
ing of Tiros II. The first-stage Thor has a
thrust of about 150,000 pounds. It is interest-
ing that the Thor vehicle used to launch Tiros I

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Figure 10-1. Placement of the Thor booster on the
launch stand for the Tiros II launch from Cape
Canaveral.

was extensively used as a training vehicle by
the military services; finally, it was obtained
by NASA and modified to the form used for the
Tiros launches. This modified Thor success-
fully performed in the launch of the Tiros I
satellite itself.

Figure 10-2 shows the vehicle on the launch
stand. The launch vehicle stands about 90 feet
high, it is about 8 feet in diameter, and at lift-
off it weighs a little over 100,000 pounds. An
impressive feature of the launch vehicle is the
rate at which it consumes oxygen. It consumes
oxygen during the boost phase at the same rate
as about 6 million people.

Table 10-1 summarizes the satellite orbital

Figure 10-2. The Thor-Delta launch vehicle standing
ready for launch in the early morning of November
23, 1960.

parameters resulting from the successful
launch- vehicle performances :

Table 10-1. — Orbit Information

Tiros I

Tiros II

Tiros III

Period, min _ .

99. 24

98. 26
420 (676)
451. 5 (726)
387. 8 (624)
0. 00727
48. 530

100. 4
475 (760)
509. 8 (820)
457. 1 (736)
0. 00593
47. 898

Average height, statute miles (km)

Apogee, statute miles (km) _

450 (720)
461. 3 (740)
436. 0 (702)
0. 00287
48. 392

Perigee, statute miles (km) _

Eccentricity. _ _ .

Inclination, deg _ _ _ _ .

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The spacecraft. — Figure 10-3 shows a familiar weighs about 280 pounds and contains a vast
view of the satellite which is 42 inches in diam- complex of optical, sensory, electronic, mag-

eter and about 19 inches high. The satellite netic, and mechanical devices that serve the

Figure 10-3. The Tiros satellite in the Tiros III configuration showing the base plate with cameras looking

downward. The top is covered with solar cells.

following functions : to detect, to store, and to
transmit the data; to control the various func-
tions; to provide memory (a clock) inside the
satellite; to control the spin rate of the satel-
lite because it is spin stabilized; to control the
power; and to control the attitude to a certain
extent. The attitude of the Tiros satellite is
the most critical problem.

Figure 10-4 shows a top view of the internal
package. The main interest here is in the sen-
sor systems. The tops of the television cameras
can be seen in the figure: two wide-angle tele-
vision systems (Nos. 5 and 30) and one of the
big tape recorders (Nos. 3 and 19) on which
the picture information is stored. The infra-
red radiation system (No. 12) and instruments

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