yee@trident.arc.nasa.gov (Peter E. Yee) (03/11/89)
Charles Redmond
Headquarters, Washington, D.C. March 10, 1989
Joyce B. Milliner
Wallops Flight Facility, Wallops Island, Va.
RELEASE: 89-30
ARTIFICIAL CLOUDS TO BE VISIBLE IN CANADA AND U.S.
Four suborbital rockets, two Black Brant Xs and two Nike-
Orions, are scheduled to be launched from Canada during the next
few weeks as part of a major NASA sounding rocket campaign.
Two of the rocketborne scientific experiments, programmed to
create artificial clouds at high altitudes over Canada, are
scheduled for launch during late March from Canada's Churchill
Research Range on Hudson Bay. These colorful barium releases
will be visible, cloud cover permitting, to residents in Central
and Eastern Canada and in North-central United States, according
to the experimenters.
The other two rockets, carrying upper atmosphere experiments
which will not be visible to residents, are scheduled to be
launched between March 16 and March 24.
The objective of the barium release payloads is to measure
electric fields aligned with the Earth's magnetic field. Such
fields are thought to be responsible for accelerating electrons
to create aurora but their locations and strengths have not been
well established by measurements. Using the barium ions as
optical tracers, the electric fields are measured by observing
how the motion of the barium ions deviates from the predictable
motion that comes from the initial injection velocity and
gravitational and "magnetic mirror" forces.
The launch window period is March 25 through April 11 with
launch opportunities each day in the late evening and early
morning. If required, there is a second launch window in late
April through early May. Clear weather conditions are required
at the ground observing sites.
Three-stage Black Brant X suborbital rockets will be used to
loft the barium payloads. The Black Brant XB is a solid-
propellant rocket about 48 feet long and 18 inches in diameter.
There will be two barium releases from each rocket payload,
one before and one after apogee. The two explosive releases will
occur from each payload at altitudes of 483 and 555 miles over
the center of Hudson Bay.
The time of the launches is selected so the releases occur
either in the post-twilight or pre-dawn period when the payloads
are in sunlight but observers on the ground are in darkness.
Project officials expect them to be visible as far away as
Chicago.
Following each release, the barium is quickly ionized
(becomes electrically charged) by the sunlight. The ejected
barium first appears greenish-white in color, becomes yellowish
and then turns to a purplish hue. The newly-created barium ions
spiral around magnetic field lines and rapidly move along the
magnetic field lines away from the Earth.
Each release will produce two luminous streaks of barium
ions which absorb and re-emit sunlight. One is a "pencil like"
beam of ions that will travel rapidly to altitudes greater than
12,425 miles above the Earth's surface. The other streak does
not have the high velocity of the first and will rise to
altitudes of only 1243 to 1864 miles . The fast, high altitude
streak probably will not be visible to the naked eye after about
5 minutes. The lower altitude low velocity streak will remain
visible for 20 or more minutes.
The "pencil-like" beams of barium ions will be tracked by
electronic intensified cameras from sites located at Churchill
and Gillam, Canada, and Los Alamos, N.M,; Houston; Richmond Hill,
Pa.; and Millstone Hill, Mass. Scanning photometers will observe
from Calgary, Canada, and from Richland, Wash.; Seeley Lake,
Mont.; Boulder, Colo.; and Channing, Mich.
The U.S. observing teams come from the Goddard Space Flight
Center, Johnson Space Center, Los Alamos National Laboratory,
Battelle Pacific Northwest Laboratory, Naval Research Laboratory,
Technology International Corp., University of Alaska, Boston
University, plus a team from University College, London.
In the other two missions of the 1989 campaign, Nike-Orion
rockets will carry a cryogenic whole-air sampler (CWAS) payload
weighing over 400 pounds into the upper stratosphere to study the
polar ozone problem and the greenhouse effect.
The CWAS payload was developed by the University of
Pittsburgh for NASA's Upper Atmosphere Research Program to
investigate the sources and losses of carbon dioxide, Nitrous
Oxide, Nitric Oxide and Methane and other trace constituents that
play a role in the ozone chemistry of the middle atmosphere over
an altitude range of 19-47 miles. The payload also will provide
an accurate technique for calibrating UARS, a remote-sensing
satellite scheduled to be launched by NASA from the Shuttle
during September 1991.
The CWAS experiments are part of a major NASA effort to
study the chemistry of the lower atmosphere at northern
latitudes. These launches will complement the extensive aircraft
and ground-based observations by NASA's polar expedition to
Norway this winter.
The CWAS payload measures the density and altitude
distribution of the major and minor chemical species in air.
This objective is accomplished by collecting large whole-air
samples during the upleg portion of the flight, returning them to
the Earth by parachute and ultimately analyzing the samples at
the University of Pittsburgh. A novel refrigeration technique is
used to freeze the air entering the payload in specially-prepared
collection cells kept at -436 degrees F. during flight.
W. A. Brence, Wallops Flight Facility (WFF), is the NASA
campaign manager. Dr. Robert Hoffman, NASA Goddard Space Flight
Center, Greenbelt, Md.,is the principal investigator for the two
Black Brant X launches, and Dave Kotsifakis is the NASA WFF
payload manager. Dr. Edward C. Zipf, University of Pittsburgh,
is the principal investigator for the two Nike-Orion launches.
Bruce Scott is the NASA WFF payload manger.