The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

376 SIM (Space Interferometry Mission)
stein earned a B.S. in mechanical engineering (1929) and
an M.E. (1934) from Rose Polytechnic Institute, and
later received an honorary doctorate from Case Institute
of Technology. He began his career with NASA’s predecessor,
NACA (the National Advisory Committee for
Aeronautics), at its Langley Research Center in 1929. In
1943, he transferred to Lewis, where he carried out pioneering
research on large-scale ramjet engines. After
World War II, Silverstein conceived, designed, and built
the first supersonic propulsion wind tunnel in the
United States. The 10-ft by 10-ft Supersonic Wind Tunnel
is still operational at Glenn. In 1958, Silverstein
moved to NACA Headquarters in Washington, D.C.,
where he helped create and then direct efforts leading to
the Mercury spaceflights. He later named and laid the
groundwork for the Apollo missions. When he returned
to Cleveland to become director of NASA Lewis, Silverstein
was a driving force behind the creation of the Centaur
launch vehicle, particularly the hydrogen-oxygen
upper stage propulsion system. He retired from NASA
in 1970 to take a position with Republic Steel. In 1997,
he was awarded the Guggenheim Medal for his “technical
contributions and visionary leadership in advancing
technology of aircraft and propulsion performance, and
foresight in establishing the Mercury and Gemini manned
spaceflight activities.” 73
SIM (Space Interferometry Mission)
A major space-based observatory in NASA’s Origins Program
and the first spacecraft to carry an optical interferometer
as its main instrument. SIM is designed
specifically for the precise measurement of star positions.
One of its prime goals will be to search for extrasolar
planets as small as Earth in orbit around nearby stars.
SIM will combine the light from two sets of four 30-cmdiameter
telescopes arrayed across a 10-m boom to
achieve a resolution approaching that of a 10-m-diameter
mirror. This will allow it to perform extremely sensitive
astrometry so that it will be able to detect very small
wobbles in the movement of a star due to unseen com-
Chronology of American SIGINT Satellites
1st Generation 2nd Generation 3rd Generation 4th Generation 5th Generation
1960s 1970s 1980s 1990s 2000+
GEO-USAF COMINT Canyon Chalet/Vortex Mercury-ELINT
GEO-CIA ELINT Rhyolite/Aquacade Magnum/Orion Mentor Intruder
HEO-USAF ELINT Jumpseat Trumpet Prowler
LEO-USAF ELINT Ferret Subsats Subsats SB-WASS
LEO-Navy ELINT GRAB NOSS NOSS SB-WASS
panions. Objects of Earth mass could be inferred around
a star up to 30 light-years away. Through a process known
as synthesis imaging, SIM will also generate images of
objects such as dust disks around stars and look for gaps
or clearings in the debris that might indicate the presence
of unseen worlds. Scheduled for launch in 2005, SIM will
conduct its seven-year mission from a heliocentric,
Earth-trailing orbit.
Simons, David G. (1922–)
A U.S. Air Force major who established a new human
altitude record of 30,942 m (101,516 ft) when he flew
aboard the second Project Manhigh mission on August
19–20, 1957. During his 32-hour flight, most of it at the
edge of space, Simons recorded that the silence of the
upper stratosphere is “like no earthly quiet” and that the
color of the sky at this height is “deep indigo, intense,
almost black.” He was among the first to report the psychologically
dangerous euphoria known as the break-off
phenomenon.
Singer, Samuel Frederick (1924–)
A physicist at the University of Maryland who proposed
a Minimum Orbital Unmanned Satellite of the Earth
(MOUSE) at the fourth Congress of the International
Astronautics Federation in Zurich, Switzerland, in the
summer of 1953. It had been based upon two years of
previous study conducted under the auspices of the
British Interplanetary Society, which had built on the
postwar research of the V-2 rocket. The Upper Atmosphere
Rocket Research Panel at White Sands discussed
Singer’s plan in April 1954. In May, Singer presented his
MOUSE proposal at the Hayden Planetarium’s fourth
Space Travel Symposium. MOUSE was the first satellite
proposal widely discussed in nongovernmental engineering
and scientific circles, although it was never adopted.
single-stage-to-orbit (SSTO)
A reusable single-stage rocket that can take off and land
repeatedly and is able to boost payloads into orbit.