BSS-601HP
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The Boeing 601 (sometimes referred to as the BSS-601, and previously as the HS-601) is a retired
communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Rad ...
bus A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a motor vehicle that carries significantly more passengers than an average car or van, but fewer than the average rail transport. It is most commonly used ...
designed in 1985 and introduced in 1987 by Hughes Space and Communications Company. The series was extremely popular in the 1990s, with more than 84 purchased by customers globally. The more advanced 601HP derivative (for "high power") was introduced in 1995. Hughes, and the 601 platforms, were acquired by
Boeing The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...
in 2000. The last commercial 601 satellite was ordered in 2001 and launched in 2004. The NASA Space Communications and Navigation (SCaN) Program Office in December 2007 selected the BSS-601HP for its third generation TDRS spacecraft, adding the two 15-foot (4.5m) diameter steerable antennas. The TDRS-M satellite, launched on August 18, 2017, became the last 601 satellite to reach orbit.


Background

The Boeing-601 model was Hughes’ first major design and development for a communications satellite with three-axis, or body stabilization. All previous Hughes satellite models (
HS-376 The Boeing 376 (sometimes referred to as the BSS-376, and previously as the HS-376) is a communications satellite bus introduced in 1978 by Hughes Space and Communications Company. It was a spin-stabilized bus, a successor to Hughes HS-333. ...
) had been cylindrical spacecraft that were spin-stabilized at 50 revolutions per minute. Design of the Boeing-601 began in 1985, with full-scale development following two years later. The new satellite's first official public presentation took place at the Telecom 87 conference in Geneva, Switzerland.


Variants

; Boeing-601HP: A high-power version of the standard model Boeing-601, it supports up to 60 transponders and 10,000 watts, making it twice as powerful as the standard 601. Innovations in
gallium arsenide Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure. Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monoli ...
solar cells, battery technology, and
xenon ion propulsion system An ion thruster, ion drive, or ion engine is a form of electrically powered spacecraft propulsion, electric propulsion used for spacecraft propulsion. An ion thruster creates a cloud of cation, positive ions from a neutral gas by ionizing i ...
s (XIPS) facilitated this upgrade. The 601HP made its debut in 1995, with upgrades in 2000 to address design and component failures. ; Ultra High Frequency Follow On (UFO): The U.S. Navy began replacing and upgrading its ultra-high frequency (UHF) satellite communications network during the 1990s with a constellation of customized HS-601 satellites known as the UFO (Ultra High Frequency Follow On) series. Eleven UFO satellites were launched between 1993 and 2003. The UHF Follow-On constellation replaced the Fleet Satellite Communications (FLTSATCOM) and the Hughes-built Leasat spacecraft. ; Third generation GOES satellites: The Geostationary Operational Environmental Satellite system (GOES), operated by
NOAA The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with forecasting weather, monitoring oceanic and atmospheric conditions, charting the seas, conducting deep-sea exploratio ...
, selected the standard Boeing 601 bus for its third generation weather satellites,
GOES-13 EWS-G1 (Electro-optical Infrared Weather System Geostationary) is a weather satellite of the U.S. Space Force, formerly GOES-13 (also known as GOES-N before becoming operational) and part of the National Oceanic and Atmospheric Administration' ...
,
GOES-14 GOES-14, known as GOES-O prior to reaching its operational orbit, is an American weather satellite, which is part of the US National Oceanic and Atmospheric Administration (NOAA)'s Geostationary Operational Environmental Satellite (GOES) system. ...
, and
GOES-15 EWS-G2 (Electro-optical Infrared Weather System Geostationary) is a weather satellite of the U.S. Space Force, formerly GOES-15 (also known as GOES-P before becoming operational). The spacecraft was constructed by Boeing, and is the last of thre ...
. This series featured a sun-pointed extreme ultraviolet sensor, a Solar X-Ray Imager (SXI), and space environment monitoring (SEM) instruments for their
space weather Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the varying conditions within the Solar System and its heliosphere. This includes the effects of the solar wind, especially on the Earth's magnetosphere, ion ...
role. ; Tracking and Data Relay Satellite (TDRS): The second generation satellites (3) used the standard 601 bus, while the follow-on third generation satellites (3) use the 601HP bus, after design changes addressing satellite failures in 1990s. The TDRS version features two 15-foot-diameter steerable graphite composite mesh antennas. These antennas are partially curled-up like a taco shell to fit within the Atlas/Centaur payload fairing.


Design


Structure

The 601 bus is divided into two modules. The first module houses the propulsion system, batteries, and electronics for the bus, and bears
launch vehicle A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage ...
loads. The second module contains shelves carrying the communications equipment, payload electronics, and heat pipes.
Solar array A photovoltaic system, also called a PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to abs ...
s, reflectors, and
antenna feed A radio transmitter or receiver is connected to an antenna which emits or receives the radio waves. The antenna feed system or antenna feed is the cable or conductor, and other associated equipment, which connects the transmitter or receiver w ...
s are mounted to the payload module.


Payload

The standard 601 platform supports up to 48
transponder In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a flight trans ...
s and provides up to 4,800 watts of power. The 601HP supports up to 60 transponders and provides up to 10,000 watts.


Failures

A significant number of Boeing 601s have experienced failures in orbit, some resulting in complete failure of the satellite.


Spacecraft Control Processor (SCP)

An unconfirmed number of 601s launched prior to August 1997 have a design flaw in their SCPs, where a tin-plated relay forms crystalline "whiskers" under certain specific conditions. These whiskers eventually caused an electrical short. Each satellite contains two SCPs and the backup unit will take control in the event of a failure of the primary unit. In some cases, both SCPs have failed, rendering the spacecraft unusable. A notable example was the Galaxy IV satellite. At least eight 601s have experienced SCP failures; four of which were double failures resulting in total loss of the satellite. Hughes switched to nickel plating on later 601s to resolve this problem, at the expense of payload weight.


Batteries

Some 601HPs have experienced problems with their batteries, resulting in a reduction of eclipse protection. This would require some transponders to be shut down during eclipse periods.


Xenon Ion Propulsion System (XIPS)

Some Boeing-601 satellites featured the optional electronic propulsion system, called Xenon Ion Propulsion System or
XIPS The gridded ion thruster is a common design for ion thrusters, a highly efficient low-thrust spacecraft propulsion method running on electrical power by using high-voltage grid electrodes to accelerate ions with electrostatic forces. History Th ...
, for station keeping. At least four satellites with XIPS propulsion have experienced partial or total failure of the XIPS system which significantly reduced the lifespan of the satellite.


Satellites based on the 601 and 601HP


See also

*
Boeing 702 Boeing 702 is a communication satellite bus family designed and manufactured by the Boeing Satellite Development Center, and flown from the late-1990s into the 2020s. It covers satellites massing from to with power outputs from 3 to 18  ...
*
Boeing Satellite Development Center The Boeing Satellite Development Center is a major business unit of Boeing Defense, Space & Security. It brought together Boeing satellite operations with that of GM Hughes Electronics' Hughes Aircraft#Hughes Space and Communications Group, S ...


References

{{Hughes satellites Satellite buses Military equipment introduced in the 1990s