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

Solar-B
A Japan-led mission, with collaboration from the United
States and Britain, to follow-on from the highly successful
Yohkoh (Solar-A). It will look at the Sun in soft
(longer wavelength) X-rays, as does Yohkoh, but will also
provide very high-resolution images in visible light.
Solar-B will carry a coordinated set of optical, extreme
ultraviolet, and X-ray instruments to investigate the interaction
between the Sun’s magnetic field and its corona.
The result will be an improved understanding of the
mechanisms that underlie solar magnetic variability and
how this variability affects the total solar output. ISAS
(Institute of Space and Astronautical Science) will provide
the spacecraft, the M-5 launch vehicle, and major
elements of each of the scientific instruments. These
include a 0.5-m solar optical telescope (SOT), an X-ray
telescope (XRT), and an extreme ultraviolet imaging
spectrometer (EIS). Britain’s Particle Physics and Astronomical
Research Council is responsible for the EIS.
NASA will provide the focal plane package (FPP) for the
SOT, as well as components of the XRT and EIS. Solar-B
is scheduled for launch in the fall of 2005 into a sunsynchronous
orbit that will keep the instruments in
nearly continuous sunlight.
solar-electric propulsion (SEP)
A form of electric propulsion in which the electrical
energy used to accelerate the propellant comes from a
solar power source, such as arrays of photovoltaic cells.
solid propellant
A rocket propellant in solid form, usually containing
both fuel and oxidizer combined, or mixed and formed,
into a monolithic (not powdered or granulated) grain.
Solid Rocket Boosters (SRBs)
See Space Shuttle.
solid-fueled rockets
Rockets that burn a solid mixture of fuel and oxidizer and
that have no separation between combustion chamber
and fuel reservoir. Gunpowder is such a mixture and was
the earliest rocket fuel. They are somewhat less efficient
than the best liquid-fueled rockets, but they are preferred
for military use because they need no lengthy preparation
and are easily stored in ready-to-fly condition. They
are also used in auxiliary rockets that help heavily loaded
liquid-fueled rockets, such as the Space Shuttle and Delta
rockets, lift off and go through the first stage of their flight.
solid-propellant rocket motor
A rocket propulsion system in which the propellantis contained
within the combustion chamberor case. The solid
Solwind 385
propellant charge is called the grain and contains all the
chemical constituents for complete burning. Once ignited,
it usually burns smoothly at a predetermined rate on all
the exposed surfaces of the grain. The internal cavity grows
as propellant is burned and consumed. The resulting hot
gas flows through the supersonic nozzle to impart thrust.
Once ignited, the combustion proceeds until all the propellant
is used up. There are no feed systems or valves.
SOLO (Solar Orbiter)
A proposed ESA (European Space Agency) Sun-orbiting
spacecraft that will carry optical instruments to view the
Sun directly from close up and from high latitudes.
SOLO will study fields and particles in the part of the
heliosphere near to the Sun, the links between activity on
the Sun’s surface and the corona, and the Sun’s polar
regions. The spacecraft will tap much of the technology
developed for Bepi Colombo, the Mercury Cornerstone
mission. The orbital design follows the Mercury Orbiter
trajectory design, and the mission will use solar-electric
propulsion (SEP), powered by a set of large cruise solar
arrays that are jettisoned after the last firing of the SEP
thrusters. Using SEP together with multiple gravity-assist
maneuvers, it will take Solar Orbiter only two years to
reach a perihelion of 45 solar radii at an orbital period of
149 days.
Solrad (Solar Radiation program)
A series of missions, conceived by the U.S. Naval
Research Laboratory in the late 1950s, to study the effects
of solar emissions on the ionosphere and also to conceal
the existence of classified intelligence satellites, known as
GRAB, that were launched at the same time. The Solrad
series was designed to provide continuous coverage of
wavelength and intensity changes of solar radiation in the
ultraviolet, soft (longer wavelength) X-ray, and hard
(shorter wavelength) X-ray ranges. All missions up to Solrad
7B were GRAB copassengers. Solrad 8, 9, and 10 were
also known as Explorer 30, 37 (or Solar Explorer B), and
44, respectively.
Solwind
A satellite designed to investigate how the solar wind
interacts with Earth’s ionosphere and magnetosphere. It
was destroyed, while still functional, on September 13,
1985, as part of a U.S. Air Force antisatellite (ASAT) test.
Launch
Date: February 24, 1979
Vehicle: Atlas F
Site: Vandenberg Air Force Base
Orbit: 310 × 317 km × 97.8°
Mass: 1,331 kg