text = "#FFFFFF"
link = "#B5FF01"
alink = "#DA01FF"
vlink = "#CC01FF"
bgcolor = "#010101">
Polar
Polar
The Mission
The Polar spacecraft is one of two NASA spacecraft which contribute to the
International Solar Terrestrial Physics Programme (ISTP). The overall goal of
the ISTP is to understand the physical mecahnisms controlling the transport of
mass, momentum and energy from the solar wind into the earth's magnetosphere.
Launch took place on February 24th, 1996. The orbit is a highly
elliptical one with its lowest point at a height of 5100km over the Antarctic
and highest point at 51000km over the Arctic. The position of the highest point
will move slowly across the North Pole during the first two years of the
mission.
The spacecraft carries nine instruments to measure particles, magnetic and
electric fields, and three instruments to make pictures in the visible,
ultraviolet and X-ray spectrla regions. UK groups participate in two of these
investigations.
Science Objectives
Polar's primary objective is to find out how much of the plasma in the Earth's
magnetosphere comes from the solar wind and how much is drawn up from the
Earth's upper atmosphere. It will take pictures of the aurora over the entire
polar cap from high above the Earth. It will measure the particles where they
are being accelerated down into the atmosphere to make the aurora.
The TIMAS Instrument
MSSL built a large imaging particle detector for TIMAS (Toroidal Imaging Mass
Angle Spectrometer) which measures the mass, energy and direction of positive
ions in the energy range from 15eV to 32keV and masses from 1(H+) to 32(O2+)amu.
The fast electronic readout allows low-density, rare, ion species to be detected
in the presence of dominant species. TIMAS objectives are to look for the entry
of plasma into the magnetosphere from the solar wind and to study the outflow of
plasma from the atmosphere over the polar caps.
Further Information
The
TIMAS Instrument page at Lockheed may be accessed, as well as the
NSSDC Polar Page, and the ISTP Polar page.
MSSL Space Plasma Physics
MSSL Home Page
Latest update: February 26th, 1995.
dmw@nojunk-removethis-mssl.ucl.ac.uk
static mirrors and a focussing particle collimator system.
Within each analyser parallel