ASTRONOMY AND ARTIFICIAL SATELLITES—-GOLDBERG 297 
low levels in the atmosphere and the lower frequencies from the higher 
levels as the stream of charged particles moves outward. However, 
some radio bursts are associated with geomagnetic disturbances while 
others are not, which suggests that some of the streams do not have 
enough energy to penetrate the solar atmosphere. To determine 
which streams do, in fact, escape from the sun, it is necessary to make 
observations at very low frequencies down to 1 megacycle or less. 
Unfortunately, radiation at these frequencies cannot penetrate the 
earth’s atmosphere because it is reflected back into space by the iono- 
sphere. Hence, it would be extremely important, as proposed by 
¥. T. Haddock, to make observations over the frequency band from 
1 megacycle to 30 megacycles from above the atmosphere. ‘The obser- 
vation of these radiofrequencies might also make possible, as an 
interesting byproduct, the measurement of the decrease of electron 
density in the column of interplanetary space between the sun and 
the earth. 
During the period that has elapsed since this lecture was given the 
National Aeronautics and Space Administration has announced plans 
for the development of orbiting astronomical observatories in co- 
operation with six observatory teams. The plans include provision 
for both solar and stellar orbiting telescopes. Design studies prelimi- 
nary to the construction of apparatus for the solar observations out- 
lined above are in progress at the University of Michigan, while other 
plans are being generated at Princeton University, at the Universities 
of Rochester and Wisconsin, at the Smithsonian Astrophysical Ob- 
servatory, and at the Kitt Peak National Observatory. These efforts 
are in addition to the ongoing programs of extraterrestrial observa- 
tion at the Naval Research Laboratory and at the University of 
Colorado. 
It is expected that instrumental payloads of about 2,500 pounds 
will be sent into orbit 500 miles above the earth. Much in the way of 
laboratory experimentation will be required to insure that the satel- 
lite and instrumentation will withstand the severe accelerations and 
vibrations during the launching operation, and also to make sure that 
the systems envisaged for the stabilization and pointing control sys- 
tem and for the recording, storage, and transmission of the data will 
indeed function correctly. However, none of the foreseeable prob- 
lems appears to be insurmountable engineering-wise, and there can 
be little doubt that a bright future awaits astronomers as they enter 
this most exciting period in history. 
