ION ENGINE POSITIONING SYSTEM Hughes Press Release November 9, 1962 By Dr. Malcolm R. Currie Associate Director Hughes Research Laboratories Transcribed by Faith MacPherson

Technical Background

The control of stationary earth satellites is one of the most important near-future applications for low-thrust space propulsion systems. The function of the propulsion system in this application is twofold, attitude control and station keeping. In the attitude control mode, the system must hold the orientation of the satellite about three axes to a specified angular accuracy for a period of years. This is accomplished by imparting small but frequent angular impulses to counteract disturbance torques which arise from such natural effects as solar radiation pressure and micrometeorite impact, and such internal effects as gas leakage and moving parts. In the station keeping mode, the control system must maintain the satellite in a stationary position relative to the surface of the earth. The two major sources of orbit perturbation (position change) of a 24 hour satellite are the triaxiality of the earth (elliptical equator) and the gravitational attraction of the sun and moon. The triaxiality effect causes the satellite to oscillate in an east-west direction with amplitude of up to 90 degrees longitude and with a period of about one year. A velocity increment of 17 ft / sec / yr is necessary to counteract this perturbation. The solar-lunar perturbations tend to pull the satellite in a north-south direction resulting in maximum change in orgit inclination (latitude of 0.948 deg / year. A velocity increment of 167 ft / sec / yr is required to correct for this latter effect. Therefore, a total velocity increment of 184 ft / sec / yr must be provided by the propulsion system each year to maintain the satellite longitude and latitude.

The Hughes Research Laboratories has recently been awarded a contract by NASA to develop an ion propulsion attitude control and station keeping system for the purpose of controlling 24 hour satellites. The system will employ cesium surface-contact ion engines to provide thrust in the nine directions necessary for complete satellite control. The ion thrustors used for station keeping will produce a thrust of 1.5 mlb whereas 0.5 mlb is the thrust level of the attitude control thrust devices.

This system, when used to control a typical 500 lb. satellite, would operate in the following manner. The station keeping engines would thrust about 10 minutes each day for the east-west orbit correction and a total of about 1 ½ hours for the north-south correction. The attitude control engines will operate only a few seconds approximately every quarter hour. The propellant required by the ion engines to hold the satellite to the desired orientation and to maintain proper station longitude and latitude for a period of three years is only 2.25 lbs.

A comparison of the weight of the ion propulsion system with equivalent cold gas systems shows that as the total impulse required increases (i.e.. as mission time or satellite weight increase), the ion propulsion system becomes more and more attractive. Most of the weight of the low specific impulse cold gas systems is in the propellant, whereas, for the ion engine most of the weight is in the power source. The advantage of the ion engine is that its over-all weight will increase very slowly with required operating time (less than 1 lb. per year). For satellite lifetimes of two or more years, ion propulsion will provide the lightest control system.

Ariane sends SBS-5 for IBM unit into orbit Hughes News Quarterly International Edition July-September 1988 Transcribed by Faith MacPherson

A European Ariane rocket blasted off from a launch site in French Guiana Sept. 8 lifting the SBS-5 satellite, a Hughes HS 376 model built by Space and Communications Group, into geosynchronous orbit.

SBS-5 is owned and operated by Satellite Transponder Leasing Corporation, a subsidiary of IBM.

SBS-5 will more than double the communications capacity of the STLC system and support a range of new customer applications of data, video, and voice services. The satellite also will provide growth capability for STLC customers on SBS-4, an HS376 satellite that was launched in 1984 by the Space Shuttle.

Both satellites operate in the Ku-band frequency. SBS-4 has 10 narrowband transponders with 20 watts of transmitting power each. SBS-5 carries 14 transponders; 10 narrowband and four wideband.

Each SBS-5 transponder also has 20 watts of transmitting power. It also has the ability to boost power levels on command by linking two transponders in parallel. This would provide 40 –watt channels, four each in the narrow and wide bands, to serve corporate requirements for high-power data networks and video broadcasting using very small aperture terminals.

SBS-5, which has a design life of 10 years, will cover the contiguous United States and provide narrowband spot beam service to Hawaii and Alaska.

The spacecraft will be the 29^th HS 376 to be placed in orbit. The “workhorse” line of satellites began in 1977 with the order for SBS-1, which was launched in 1980.

Versions of the HS 376 are in operation by five companies in the U.S., and serve as the national communications satellites for Australia, Brazil, Canada, Indonesia, and Mexico.

Reagan okays China launch of U.S. satellite Hughes News Quarterly International July-Sepember 1988 Keith Bass Transcribed by Faith MacPherson

President Reagan has given conditional approval to a first-time export of telecommunications satellites to the People’s Republic of China for launch into space.

Export of the Hughes-built satellites, the first to a non-Western country, must now be approved by Congress and allied nations.

The satellites in question are two AUSSAT B spacecraft under construction at Space and Communications Group for AUSSAT Pty., Ltd., owner and operator of Australia’s domestic satellite system.

“Hughes is pleased with the administration’s decision to allow the AUSSAT satellites to be launched from the People’s Republic of China,” and Senior Vice President Tony Iorillo, SCG president.

“We made a good faith export license application on behalf of AUSSAT, and we are happy that it is on its way to full approval.”

As part of its AUSSAT B agreement with Hughes, AUSSAT Pty., Ltd., requested that, in addition to considering launches on the American Titan or Atlas Centaur, Hughes acquire export licenses that would allow launch of the satellites on various non-U.S. launch vehicles, including the Chinese Long March.

Ultimately, AUSSAT Pty., Ltd., will determine which launch vehicle will be used.

SCG is working under a contract, which ultimately may be valued at about $500 million, to build the two HS 601 spacecraft, and there is an option for a third.

If exportation is approved, the first of the two satellites could be launched in mid-1991 from the Chinese Long March launch vehicle. Full approval of the launch could take two months.

The State Department said that its approval does not mean the United States is relaxing its prohibition on the export of satellites to the Soviet Union for launch on its rockets.

In addition, the Coordinating Committee on Multilateral Exports, an organization of allied nations, must also approve the export of the satellite.

SCG officials see no security danger in exporting the satellites to China. The Long March launch requires very little data to be transferred to the Chinese.

Information would be provided to enable certain mechanical, electrical, and thermal interfaces between the satellite and launch vehicle. Some of this information is already in the public domain. There would be no transfer of data on design, manufacture, or manufacturing processes.

“Our position is that allowing U.S. satellite manufacturers the opportunity to offer their customers the widest possible range of launch choices helps keep the industry competitive,” Mr. Iorillo said.

“If foreign satellite manufacturers have access to launch opportunities that we do not, then they will have a distinct edge during negotiations for satellite construction business.”

Mr. Iorillo added that U.S. government action permitting use of the Long March should not have a significant impact on U.S. launch vehicle suppliers. The ability of the Chinese to compete for commercial launches is small, and the U.S. launch vehicle suppliers currently have orders for 54 U.S. government and 16 commercial launches valued at approximately $6.2 billion.

Australia’s satellite system consists of three Hughes-built AUSSAT A satellites, control stations in Sydney and Perth, and a network of ground communications stations throughout Australia.

The first two satellites were placed in orbit by the Space Shuttle in 1985, and the third was launched by the European Ariane rocket last September.