Conference 7.286::space

961.0. "NASA's POLAR Spacecraft" by NETCAD::BATTERSBY () Fri Feb 23 1996 13:06

Article: 8128
From: [email protected] (Ron Baalke)
Newsgroups: sci.space.news
Subject: POLAR Ready for February Launch
Date: 8 Feb 1996 10:57:01 -0800
Organization: Jet Propulsion Laboratory
Sender: [email protected]
 
Donald Savage
Headquarters, Washington, DC                February 7, 1996
(Phone:  202/358-1547)
 
Jim Sahli
Goddard Space Flight Center, Greenbelt, MD
(Phone:  301/286-0697)
 
George Diller
Kennedy Space Center, FL
(Phone:  407/867-2468)
 
Keith Takahashi
McDonnell Douglas Public Relations, Huntington Beach, CA
(Phone:  714/896-1302)
 
RELEASE:  96-26
 
POLAR LAUNCH COMPLETES GLOBAL GEOSPACE SCIENCE CONSTELLATION
 
       NASA's Polar spacecraft, scheduled for a February launch 
from Vandenberg Air Force Base (VAFB), CA, is a key element of 
a constellation of satellites which promise to revolutionize 
understanding of the Sun's influence on Earth's space 
environment.  
 
       "Polar will launch space physicists on a new voyage of 
discovery and exploration," said Dr. Robert Carovillano, Polar 
Program Scientist at NASA Headquarters, Washington, DC.  "Polar 
is the main link in a very critical chain of laboratories in 
space which will study both the very inner and outer frontiers 
of the chain of processes which intimately connects the Sun 
with the Earth and the other planets.  This launch marks the 
beginning of a new era in our understanding of the interactions 
of these tremendous forces."
 
       The final mission in NASA's Global Geospace Science 
(GGS) program, the Polar laboratory will be launched in an 
orbit which loops over the Earth's poles for a three-year 
mission to study the movement of energetic charged particles 
above the polar regions.  It will give scientists new 
perspectives on how Earth's space environment is affected by 
continual bombardment from radiation and particles from the 
Sun, data which eventually could help scientists forecast 
"space weather".  
 
       The most well-known effects of these particles are the 
sometimes spectacular curtains of light known as the Northern 
and Southern Lights, or auroras.  More serious effects are the 
damage the particles can cause when severe solar-driven storms 
damage spacecraft electronics and even disrupt communications 
and power networks on Earth -- systems on which society is 
becoming ever more dependent.  
 
       "Polar will help us in a new area of research that 
scientists call 'space weather' where the objective is to make 
relevant observations of our solar-terrestrial system.  Then, 
we will put that data into models that will predict where and 
when various types of space disturbances will occur," said Dr. 
Robert Hoffman, Polar Project Scientist at NASA Goddard Space 
Flight Center, Greenbelt, MD.  "Information from Polar about 
the radiation environment that satellites and spacecraft 
experience will enable the development of better radiation-
tolerant technology for space systems."
 
       The Polar laboratory will perform simultaneous, 
coordinated measurements of the key regions of Earth's 
geospace, or space environment, with WIND, which was launched 
November 1994 and is now measuring properties of the solar 
wind.  A large array of ground-based scientific observatories 
and mission-related theoretical investigations also will be 
involved.
 
       NASA is collaborating with the European Space Agency and 
the Japanese Institute of Space and Astronautical Sciences in 
three additional solar-terrestrial missions, Geotail, SOHO and 
Cluster.  These missions, together with GGS, make up the 
International Solar Terrestrial Physics (ISTP) science 
initiative.  
 
       The Polar spacecraft, carrying 11 instruments, is 
scheduled for launch on a Delta II rocket from the Western 
Space and Missile Center, at VAFB.  The instruments, supplied 
by industry and university teams as well as by NASA, will study 
a vast range of phenomena from electromagnetic radiation to 
charged particles from very low to relativistic energies.  
Especially important on Polar are three high resolution imagers 
looking down on the Earth's polar region.  The instruments will 
image at wavelengths from the visible to ultraviolet and into 
the X-ray region.
 
       "The aim of ISTP is to understand the physical effects 
of solar activity on interplanetary space and the Earth's space 
environment.  This will lead to the capability of predicting 
the responses of each part of the Sun-Earth system to solar 
activity," said Dr. Mario Acuna, ISTP Project Scientist at 
Goddard.
 
       Polar's orbit around the Earth will be inclined 86 
degrees to the equator.  The altitude of the furthest point 
from the Earth on the orbit -- the apogee -- will be eight 
Earth radii (32,000 miles), and the closest point -- the 
perigee -- will be 0.8 Earth radii (3,200 miles).
 
       Polar is a spin-stabilized cylinder-shaped spacecraft 
7.9 feet in diameter and 6.9 feet high with many appendages for 
instrument sensors.  The dry weight of the spacecraft is about 
2,200 pounds with an additional 660 pounds of hydrazine 
propellant for orbit and attitude control.  
 
       Several NASA facilities will play key roles in the 
collection and dissemination of Polar science data.  NASA's 
Deep Space Network will be used to command the spacecraft and 
to collect Polar science data via radio link.  At Goddard, raw 
data will be processed, organized and stored.  The project's 
Central Data Handling Facility will produce "key parameter 
data" for rapidly surveying the much larger volume of raw data 
from the mission.  Detailed analysis of the data will be 
performed by investigators at their own sites and the data will 
be shared through the NASA Science Internet connections 
throughout the United States, Japan and Europe.
 
Spacecraft Pre-Launch Processing
 
       The Polar spacecraft arrived at Vandenberg aboard a C-5 
military aircraft on Oct. 16, 1995.  It was transported to NASA 
Hangar 836, NASA's spacecraft and launch vehicle checkout 
facility at Vandenberg, to begin prelaunch checkout activities.  
This work included propulsion system checks and electrical 
system testing, and a series of functional tests which included 
checkout of each of the spacecraft's instruments.
 
       On Nov. 10, Polar was transported from Hangar 836 
located on South Vandenberg to NASA Hazardous Processing 
Facility 1610 located on North Vandenberg near Space Launch 
Complex 2.  There the spacecraft was fueled with its hydrazine 
control propellant on Nov. 14 - 15.  Polar was transported to 
the launch pad on Jan. 23 and mated to the Delta II rocket.  
The nose fairing installation activities placing it around the 
spacecraft began on Jan. 29.
 
Delta-233 Processing
 
       Delta-233, a Delta II launch vehicle manufactured by 
McDonnell Douglas, began its preparation at NASA's Space Launch 
Complex 2 with the erection of the first stage on Nov. 29, 
1995.  The second stage was hoisted atop the first stage on 
Dec. 1, and the solid rocket boosters were erected in sets of 
three on Dec. 5 - 7.
 
       The electrical qualification testing of Delta-233 was 
performed on Jan. 5-6.  An electrical test to verify the in-
flight events which the vehicle normally performs was conducted 
on Jan. 17.  The vehicle was partially loaded with liquid 
oxygen for a first stage leak check on Jan. 18.  A Flight 
Program Verification was performed on Jan. 25, a test which 
verified the actual flight events and associated flight 
software to be used on the Delta-233/ Polar mission.
 
       Loading of the second stage with its complement of 
storable propellants, an activity which normally occurs before 
the countdown begins, was scheduled to occur two days before 
launch on Feb. 22.  Loading of the first stage with liquid 
oxygen and RP-1, a highly refined kerosene, is performed in the 
terminal countdown sequence which begins approximately three 
hours before launch.
 
       Information about the Polar mission and the ISTP are 
available on the Internet at the following home page locations:
 
Polar:    http://www-istp.gsfc.nasa.gov/ISTP/ggs_project.html
 
ISTP:     http://www-istp.gsfc.nasa.gov/
 
       Goddard manages the Polar project for NASA 's Office of 
Space Science, Washington, DC. 
 
 
                           - end -
 
 

    The POLAR launch from VAFB was scrubbed this morning due to 
    high winds at same altitude as the Delta rocket would have
    ecperienced maximum dynamic pressures. It has been postponed
    until tomorrow morning when they will try again. Launch time
    is I think scheduled for about 3:30am PST or thereabouts.
    
    Bob