We inaugurate a new column aimed at capturing the spirit and excitement of Amateur Radio and amateur-related radio communication in space.

Ten years ago this month there was a spectacular moment in Amateur Radio satellite history. For the first time ever, on July 17, 1991, thirteen OSCARs were active in orbit at the same time.

The birds flying high at that time were AO-10, UO-11, AO-13, UO-14, AO-16, DO-17, WO-18, LU-19, FO-20, AO-21/RS-14, the RS-10/RS-11 combo, the RS-12/RS-13 combo and the brand-new UO-22.

That moment happened because hams at the University of Surrey in the United Kingdom had designed and built yet another small satellite, UoSAT-F, which was launched that July 17 to a low, sun-synchronous, circular orbit on a European Ariane rocket from Kourou, French Guiana, South America.

The UoSAT-5/UO-22 satellite, courtesy of Surrey Satellite Technology Limited (SSTL).

Once in polar orbit, 480 miles (800 km) above Earth, UoSAT-F, also known as UoSAT-5, was renamed UoSAT-OSCAR-22.

Some of the costs of UO-22 had been borne by the organization SatelLife, formed by International Physicians for the Prevention of Nuclear War, an organization that had received a Nobel Peace Prize in 1985.

SatelLife used the pacsat to start HealthNet, an international not-for-profit e-mail network for health professionals. Early users included five African medical schools, which linked up with HealthNet to receive fresh medical literature and exchange electronic mail by satellite.

HealthNet message packets were transmitted on non-amateur frequencies near 428 MHz, not far from UO-22's amateur downlinks at 435 MHz. When off-duty from HealthNet, UO-22 would switch to Amateur Radio frequencies.

Pacsats Explained Pacsats are low-orbit message-handling satellites that fly around the globe picking up text messages from individual ham stations, storing them in memory, and relaying them to other terrestrial stations. These mailboxes in the sky permit amateurs on one side of the world to place messages on the satellite's bulletin board to be removed by others when the satellite is on the far side of the globe. Mail stays in the satellite for long periods, of course, awaiting radio commands from an addressee. Busy operators on the ground could put their satellite stations on autopilot. They would program their computers to determine when satellites would be overhead. Most pacsats pass over the North and South Poles every hour and a half and over any one point on the surface four times a day. One is overhead for only a dozen minutes or so at a time. When operating automatically, a ground-station computer would fire up its radio at the appointed hour and send up a signal asking the satellite if any messages were on hand. If messages for that ground station were stored in the satellite, the satellite's computer would order them sent down. The computer on the ground then could store them for future reading by its human operator and turn off its radio as the satellite passed out of sight over the horizon. A pacsat makes it cheap and easy to send messages, data and images in or out of developing regions. Scores of portable ground stations are linking underdeveloped countries to medical, weather, agriculture and engineering databanks. These electronic mailboxes in the sky can link with inexpensive, portable ground stations built around a suitcase of computer, radio and battery where no power lines exist. A pacsat often flies low enough for small ground stations to use simple whip antennas, made from coat hangers if necessary, to hear the satellite. A gateway is a satellite ground station acting as a bridge between a pacsat and a terrestrial network. Automated gateways upload and download traffic without human operators

In congestion very similar to overcrowding problems on the satellite UO-14, hams using UO-22 were limiting access for non-amateur SatelLife stations even as the non-amateur transmissions interrupted amateur activity. Surrey had obligations to SatelLife and Volunteers In Technical Assistance (VITA), and it moved to resolve the congestion in 1992. Amateur Radio service was dropped from UO-14 altogether in favor of non-amateur SatelLife and VITA, and all ham activity was moved to UO-22. The amateur payload aboard UO-14 was turned off, and its onboard non-amateur Healthsat-1 payload was switched on to serve VITA, which used it to send medical messages to Africa.

Her Majesty Queen Elizabeth II was touring the UoSAT control room in 1992 when UO-22 flew overhead and transmitted a synthesized-voice greeting. Then UO-14 delivered a message to Her Majesty from President Fredrick Chiluba of the Commonwealth nation of Zambia. The Queen left a reply message, which was returned to Zambia by UO-14.

UO-14 returned to work as a ham satellite last year. Following its launch in January 1990, it operated for 18 months as an amateur message store-and-forward satellite, while its non-amateur Healthsat-1 package waited to start its work. After eight years of use sending medical traffic to Africa, its onboard computer no longer was able to handle messages, and UO-14 was re-assigned in March 2000 as a single-channel FM voice repeater for Amateur Radio. Its uplink is 145.975 MHz, and its downlink is 435.070 MHz.

UO-22 is a pacsat (see sidebar, "PacSats Explained") with a bulletin board system (BBS), but the satellite's most remarkable feature may be its Earth observation payload--a charge-coupled device (CCD) television camera with 110-degree wide-angle lens showing a field of view nearly the same size as the satellite's footprint. The camera samples the ground through an area array sensor in the spectral band at 600-615 nm. The area of one of its images is about 1500´ 1080 km.

UO-22 snaps three or four shots a day, each of a ground area 994 by 1118 miles. Notable pictures have included Italy, showing the familiar boot outlined by the Mediterranean, Adriatic, and Tyrrhenian Seas, and Yugoslavia and Greece; an Antarctic iceberg; Bulgaria and Romania; Denver; Cuba and Haiti; Denmark and the Netherlands; haze over Djibouti, Somalia and Yemen; French Guyana; eastern South Africa; Egypt and Sinai, the Nile Valley and the Upper Nile; the Gulf of Mexico; Equatorial Africa; Kuwait and Persian Gulf smoke plumes; Limerick, Ireland; the Balkans; North Africa; the Great Lakes; northern Australia; Florida and the Mississippi Delta; Spain, Portugal and Mahgreb; California; the Red Sea; Korea; and the Straits of Hormuz.

The 110-pound satellite also carries radiation dose experiments, horizon sensors, and magnetometers, one inside and the other on a small boom protruding above the spacecraft. UO-22 has a 15-ft. gravity-gradient boom with a five-lb. weight on the end which provides restoring torque to keep the camera lens and radio antenna pointed to Earth.

UO-22 is in an 800 km circular orbit, with 98° inclination. Jim Weisenberger, AA7KC, recently reported to AMSAT that UO-22 is operational with good downlink efficiency and heavy traffic.

UO-22's uplink is 145.900 or 145.975 MHz packet 9600 bit/s FM FSK and the downlink is 435.120 MHz FM packet 9600 bit/s FM FSK The satellite's broadcast call sign is UOSAT5-11 and its BBS is UOSAT5-12.

More information on the satellite is available on the Surrey Satellite Technology Ltd Web site. Click on "missions," then select UoSAT-5].

For more information on UO-22, visit the AMSAT Web site and http://www.amsat.org/amsat/news/wsr.html#uo-22.

For more information on UO-14, visit the AMSAT Web site and http://www.amsat.org/amsat/news/wsr.html#uo-14.

The AMSAT Web site also has a history of all amateur satellites.

Editor's note: ARRL Life Member Anthony R. Curtis, K3RXK, lives in Florence, Kentucky. He describes himself as "a dc-to-daylight kind of guy." He's interested in AMSAT, ARES, digital, HF, VHF, UHF, CW, SSB, FM, QRP, contesting and DX. Licensed since 1954, he originally held the call sign W8TIZ. An Extra class op with a PhD in mass communication, Curtis has written 72 books about space, astronomy, computers and electronics. He is editor of Space Today Online <http://www.spacetoday.org>. Active as an ARRL field volunteer, Curtis served as Section Emergency Coordinator for the Maryland-DC Section and as net manager for the Maryland Emergency Phone Net. He now serves as an ARRL Educational Advisor and a Great Lakes Division Assistant Director. He also has been president of clubs and repeater associations. Curtis is employed as associate dean for academic information services at the Union Institute University in Cincinnati, Ohio. Readers can contact Tony Curtis via e-mail <k3rxk@arrl.net>.

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