What Does the Future Hold? 
1-2 m accuracy 
o Laser altimeter 
The ERTS-1 satellite is nearly defunct. Though the empty Skylab 
is still in orbit, there are no plans to reoccupy it. The ERTS-B 
satellite is identical to ERTS-1. It is ready for launch late in 1974 
or early in 1975, though final approval has not yet been given. ERTS-C 
has been discussed. Its sensor package would be similar to that of 
ERTS-B except that the focal length, scale, and resolution of the RBVs 
may be doubled, and the MSS may carry a thermal infrared channel. Nobody 
knows if ERTS-C will ever materialize. NASA has conducted studies for 
an Earth Observatory Satellite (EOS) for launch in the 1980s. It would 
carry a thematic mapper (TM) much like the MSS on ERTS except that reso 
lution would be increased to 30 m. It would also carry a high-resolution 
pointable imager (HRPI) not unlike the ERTS RBV except that resolution 
would be 10 m. But EOS is not an approved or funded system. 
Next year (1975) will come the Apollo-Soyuz Test Project (ASTP). • 
There was extended study about putting large camera systems derived from 
the lunar program aboard ASTP. However, due to the short time in orbit 
and spacecraft constraints on power, space, and weight, these plans were 
abandoned. ASTP will carry nothing more elaborate than hand-held 
Hasselblads. 
Beyond that there is the Space Shuttle, a manned recoverable vehicle 
capable of launching and retrieving various types of special-purpose 
spacecraft. One proposal is for a manned Spacelab with a variety of 
sensors. Processing and interpretation would be done aboard. 
Studies have been conducted for a standard camera package to be 
carried on all Shuttle sortie missions. They came up with the unimaginative 
selection of 35 mm Nikon, 70 mm Hasselblad with interchangeable lenses, 
and the S-190B camera from Skylab. 
It takes no great amount of photogrammetric analysis to determine 
the characteristics of a system which could make a substantial contri 
bution to standard topographic mapping. In 1967 the National Academy of 
Sciences (NAS) undertook such a study (13) and recommended a system , 
comprising: ■, , 
305 mm focal length 
230 x 460 mm format 
150 mm focal length 
70 mm format 
610 mm focal length 
108° sweep 
123 mm film width 
25° convergence angle 
o Frame camera 
o Stellar cameras (2) 
o Panoramic camera