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| The Tactical Satellite-4
spacecraft is photographed in near-final flight configuration at the
Alaska Aerospace Corp.'s Kodiak Launch Complex, Kodiak, Alaska. The
992-pound spacecraft is scheduled to lift off on Sept. 27 for a
planned year-long mission. U.S. Naval Research Laboratory photograph |
KIRTLAND AIR FORCE BASE, N.M -- If U.S. Navy Lt. Michael P. Murphy had
had the capability in June 2005 to communicate to a satellite from
underneath the cover of rocks requesting help while he and three fellow
SEALs took enemy fire in the Hindu Kush Mountains of Afghanistan, the
posthumously Medal of Honor recipient might still be alive today.
Due to the rugged terrain, Lt. Murphy positioned himself in open space in
order to contact his headquarters via spacecraft and in doing so, he
became vulnerable to the adversary's attack.
Six plus years later, the Naval Research Laboratory-led Tactical
Satellite-4, scheduled to launch Tuesday on a Minotaur IV rocket from the
Alaska Aerospace Corp.'s Kodiak Launch Complex, Kodiak,
Alaska, features a communications experiment comprised of 10 ultra high
frequency channels, which can be
accessed by the deployed warfighter regardless of the landscape.
"I am really excited about TacSat-4. It is a little bit of a surprise as
not many people have paid attention to it. It is sort of an underdog
mission," said Dr. Peter M. Wegner, director, Operationally Responsive
Space Office, here. "Nevertheless, when the spacecraft gets into orbit, it
is going to open some eyes as to what small satellites can do in providing
big time capabilities to the warfighter."
Following lift off, TacSat-4, scheduled for a year-long mission, will
undergo a two-week evaluation period as program members serving at the
NRL's Satellite Operations Center, Blossom Point, Md., conduct checkouts
of the COMMx payload and other support systems. Shortly thereafter, the
spacecraft's lone trial will be exercised during its initial five months
of flight. During that time period, combatant commands and satellite
communication personnel will also perform payload tasks utilizing the
classified, web-based Virtual Mission Operations Center.
Wegner's organization serves as a significant supporter of the TacSat-4
project as it has funded the launch, the spacecraft's Joint Military
Utility Assessment, which will be conducted during the first 150 days of
the experimental mission and the satellite's inaugural six months of
operational use.
Once placed in space, TacSat-4 will maintain a highly elliptical orbit of
435 miles by 7,470 miles at a 63.4-degree inclination. This unique flight
path, three times closer to the Earth than most communications spacecraft,
which operate directly above the equator in geostationary orbit with a
period equal to the Earth's rotation, will enable TacSat-4 to provide
four-hour coverage in the northern hemisphere during each of its six daily
treks around the globe.
Because of TacSat-4's closer proximity to the planet, deployed military
members will soon have the unique capability of using a hand-held radio
and/or manpack radio to contact the spacecraft using the 10 UHF channels.
Likewise, various users and missions will have access to TacSat-4 through
the VMOC.
"Being able to communicate on the move with a hand-held, legacy military
radio is huge. This capability does not currently exist," Wegner said.
TacSat-4 serves as a collaborative effort, which includes participation
from John Hopkins University's Applied Physics Laboratory, Air Force
Research Laboratory, Air Force Space and Missile Systems Center, Orbital
Sciences Corp., ATK Spacecraft Systems and Services, Ball Aerospace &
Technologies Corp., The Boeing Company, Raytheon Company, General
Dynamics, Massachusetts Institute of Technology Lincoln Laboratory, Sierra
Nevada Corp., Design Net Engineering, AIS Corp., Microcosm, Inc., and
Space Systems/Loral.
"With this capability, we want to make sure that troops with hand-held
and/or man pack radios will be able to talk to TacSat-4. With the
spacecraft's payload comprised of 10 UHF channels, it will fill in areas
where there is not much satellite communication coverage now, said Michael
S. Hurley, TacSat-4 principal investigator, NRL. "In addition, the VMOC
provides interface between the user and the satellite. As a mission
planning tool, it takes the user's input and requests to ops within 24
hours. TacSat-4 will significantly enhance the warfighter's communication
capability, and in the process, save lives."
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