Evening star., 1953-01-07
InterpIonetory Flight
Not Just Around Corner
Mons Limit at Present Time
Is Approximately so Miles

Mons Limit at Present Time
Is Approximately 50 Miles
By Thomos R. Henry
someday. perhaps, man may fly to
the moon or the planet Venus.
But right now his limit is about 80
miles above the earth. Theoretically,
such an altitude is possible for q
human being today. although 1t prob
ably will be long time before any
body tries it.
Above so miles any man-carrying
vehicle would be entering into q vast
unknown from which the chance Of
getting back to earth alive would be
close to zero.
This is the commonsense view Of
the present status of space fight, which
lots OF folks seem to think is just
around the corner. The view was pre-
Sented by DR.. M. w. Rosen, head Of
the rocket section Of the Naval Re-
search Laboratory.
There are. he points out, three zones
to be considered. One reaches an al
titude of Is miles. There is one unof-
ficial record Of fight to that alti-
tude. about the highest that can be
reached with any sort Of an airplane,
from which the pilot got back alive.
This represents the greatest distance
man actually has been beyond the
earth.
The Distant Zones.
Second Is the IS to 50-mile zone.
Nobody has ever been there, but theo-
retically such voyage with q safe re.
turn Is quite possible.
Rockets have been built" Dr. Rosen
says. (which can ascend to so miles
and carry the necessary payload in.
volved in transporting human being.
The significance of the 50-mile height
is that, parachute recovery has been
successful only below this altitude.
Moreover, the accelerations encountered
on the ascent are within the tolerance
limit of human beings and the maxi
mum velocity Is sufficiently low SO
that the vehicle skin temperature will
not tax the capacity of known materials
and techniques of construction. The
most important feature of fight to
less than SO miles is that its duration
will be only matter Of minutes. Many
of the difficult problems which would
be involved in higher flights, such as
effects of cosmic and solar radiation.
meteor collisions and free falls and a
vacuum. will be ignored. Because the.
flight will be so short it will not be
necessary to make elaborate provisions
for food, oxygen, elimination of wastes
and maintenance Of temperature"
Rocket Is q Problem.
A problem still unanswered, he points
out. involves the reliability Of the
rocket. Rockets have been sent up. and
parachuted safely to earth. which
could have carried man. But. DR..
Rosen says, "the probability Of re-
turning man safely 80 times out Of
a hundred is very much smaller than
the probability of safe return one time
out of a hundred"
Still, 1t may not be long before
some adventurous pioneer reckless of
living will 60 into the Is to 50-mile
zone with a fair chance Of coming
back to tell about it.
But, says DR.. RoSen, "Above so miles
the situation is entirely different. At
tempts at parachute recovery Of inStru-
ments have not been successful. De-
pending on the altitude to be reached.
the accelerations could be beyond
human endurance limits and vehicle
skin temperatures above the melting
points of available materials. The
Viking rocket. which reached an alti-
tude of 1856 miles, could have carried
a man, but no one could have ensured
his safe return. No one could even
have calculated the probability Of his
survival.
Many Bars Cited.
Besides the unknown difficulties, such
as exposure to cosmic radiation and
collision with meteors, DR.. Rosen says
there are some which are easy to pre-
dict, though they are not so easy to
solve. In long fight, elaborate equip
ment requiring continuous power
source will be necessary to provide the
human passenger with the necessities
of life. Such equipment as we'll as
that, needed for guiding the vehicle, will
have to be automatic in operation be-
cause the long flight would probably
impose terrific physical and physiolo-
gical strains on the passenger"
All proposals for getting above tho
50-mile zone. to say nothing Of inter-
planetary travel, assume the use Of
atomic energy. The American public
has. Of course, been tremendously over
sold on it. It's customary nowadays
to assume that anything imaginable
can be done, somehow or other, with
this fabulous atomic energy"
"The application is important" says
DR.. Rosen, "but its value has been over
estimated. There Is practical limit
on the temperature at which rocket
motor can operate and it matters little
whether the heat has been generated
by nuclear or molecular reactions. All
rockets are propelled by the election Of
matter and our atomic rocket, like our
present rockets, will have to carry q
working fluid"
Questions and Answers