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

TWINS (Two Wide-angle Imaging
Neutral-atom Spectrometer)
A mission consisting of two identical, widely separated
satellites in high-altitude, high-inclination orbits, which
will enable the three-dimensional visualization and resolution
of large-scale structures and dynamics within the
magnetosphere. A MIDEX (Medium-class Explorer),
TWINS will extend the detailed study of energetic neutral
atoms in the magnetosphere that began with the
IMAGE mission in 2000. TWINS instrumentation is
essentially the same as the MENA (Medium-Energy Neutral
Atom imager) instrument on IMAGE. However, the
capability of TWINS to carry out stereo imaging will
greatly extend understanding of magnetospheric structure
and processes. The TWINS satellites are scheduled
for launch in early 2003 and early 2004 into orbits with
apogees of 7.2 Earth-radii and inclinations of 63.4°.
two-body problem
The problem of describing the motion of two objects
that are orbiting around each other. It is easily and accu-
Tyuratam 451
rately solved using Newton’s law of universal gravitation.
The solutions are conic sections. Far more complex is
the three-body problem, for which precise solutions are
available only in special cases, such as that of Lagrangian
points.
two-stage-to-orbit (TSTO)
A reusable launch vehicle that uses an air-breathing first
stage and a separate, or parallel, rocket-propelled second
stage. Examples include Sanger’s space plane and Boeing’s
Beta. Various two-stage-to-orbit schemes are being
considered as a replacement for the Space Shuttle as part
of NASA’s Space Launch Initiative. See single-stage-toorbit.
2001 Mars Odyssey
See Mars Odyssey, 2001.
Tyuratam
See Baikonur Cosmodrome.