Exploring the Unknown - NASA's History Office

194
OBSERVING THE EARTH FROM SPACE
. . . gives the albedos for various ground covers. Applying these values to Fig. 2, it can be
seen that, except for the case of newly fallen snow combined with clouds thicker than
600 meters and the case in which the background albedo approaches very close to cloud
albedo, 500-ft resolutions are obtainable over a wide range of conditions.
There is one other factor that might limit contrast and, therefore, resolution. This is
aerial haze between the camera and the ground. As has recently been shown in several
[11] [original placement of “Fig 2—Available contrast with varying cloud and background
albedos”] V-2 photographs, this problem is almost completely solved by use of an infrared
filter in the optical system.
Fig. 2—Available contrast with varying cloud and background albedos
From the foregoing section we may conclude that, from the standpoint of area coverage
and resolution, weather observations from a satellite are a definite possibility.
[12] Table 5*
SURFACE ALBEDO AND SCENE CONTRAST OF CLOUDS
AGAINST VARIOUS BACKGROUND SURFACES
Ground Surface Albedo + References ±
Fresh snow .80-.93 1, 3, 4
Old snow, sea ice .40-.60 3, 4
Brown soil .32 1
Grass .10-.33 4
Green leaves .25 1
Sandy loam .24 2
Sand .13-/18 3
Asphalt paving .15 2
Dry earth .14 4
Rock .12-.15 4
Moist earth .08-.09 2, 4
Cultivated soil, vegetable .07-.09 3
Smooth sea surface
Solar elev 5 deg .40 3
Solar elev 10 deg .25
Solar elev 20 deg .12
Solar elev 30 deg .06
Solar elev 40 deg .04
Solar elev 50-90 deg .03
* This table was prepared by Dr. R. S. Wehner and is included in the RAND general
report on the satellite (see footnote 1 . . .).
+ Values of albedo apply to illumination by “white” light or sunlight.
± References:
1. International Critical Tables, 1929 ed., Vol. 5, p. 262.
2. Handbook of Chemistry and Physics, 1942 ed., pp. 2147–2148.
3. H. Landsberg, Handbook of Meteorology, McGraw-Hill Book Company, Inc., New
York, 1945, p. 932.
4. J. Charney, Handbook of Meteorology, McGraw-Hill Book Company, Inc., New
York, 1945, p.296.