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The 1986 shuttle Challenger explosion caused a temporary shortage of spaceflight opportunities for satellite makers around the world. Competition from commercial satellite owners for space aboard rockets meant amateur radio satellites, which had received many free rides over the years, would have to pay for some future launches.
Like civilian and military satellites, OSCARs had been getting heavier and larger. Smaller satellites would fit in places on rockets reserved for lead ballast and would need only modest launch services. The answer for amateur radio would be a radical design departure-microsatellites.
AMSAT's new standard spacecraft would be very small in size and weight, making possible cheap launches. Each microsat was to be so compact and lightweight it could be launched to orbit by even the smallest space booster.
The microsats could fit where larger satellites couldn't, making more launch opportunities available. They were even smaller than payloads designed for NASA shuttle GAScans.
Amateur satellite designers couldn't command vast budgets, supercomputers and thousands of technicians like major aerospace firms. Instead, the volunteer radio amateur community went back to its experimenter roots and showed that back-of-the-envelope designs could be turned into state-of-the-art spacecraft.
AMSAT received an opportunity in 1989 to show off its new technology when the European Space Agency needed to test a new payload carrier.
ESA had a new piece of hardware called ASAP-Ariane Structure for Auxiliary Payloads-which was a large flat ring to hold small satellites at equal distances around its level surface. The idea was to give small secondary payloads inexpensive rides to space alongside major satellites.
To test the new structure, AMSAT and UoSAT built six small amateur radio satellites for a free ride to space on an ASAP aboard an Ariane flight.
The six microsats launched January 22, 1990, by an Ariane launcher from Kourou, French Guiana, to 500-mi.-high polar orbits were:
Microsats shared a standard framework design, but each was outfitted with electronics suited to its particular mission. Compared with the massive proportions and tonnage weights of civilian and military communications satellites, the pee-wee microsats were nine-inch cubes under 25 lbs. each.
- UoSAT-OSCAR-14 (UO-14) from Surrey,
- UoSAT-OSCAR-15 (UO-15) from Surrey,
- AMSAT-OSCAR-16 (AO-16) from North American AMSAT,
- DOVE-OSCAR-17 (DO-17), also called Peacetalker, from Brazilian radio amateurs,
- WEBERsat-OSCAR-18 (WO-18) from Weber State University, and
- LUsat-OSCAR-19 (LO-19), from Argentine radio amateurs.
AO-16, DO-17, WO-18 and LO-19 were designed at Boulder, Colorado, and other cities in the U.S., Argentina, Brazil and Canada, by AMSAT-North America, AMSAT-Argentina, BRAMSAT (AMSAT-Brazil) and the Center for Aerospace Technology (CAST) at Weber State University, Ogden, Utah. AMSAT volunteers at the Microsat Lab in Boulder assembled their own AO-16 as well as DO-17 for BRAMSAT, WO-18 for Weber, and LO-19 for AMSAT-Argentina.
The hamsats were shipped to the European Space Agency launch site in French Guiana where they were attached to the ASAP.
The six ended up in nearly-perfect Sun-synchronous orbits passing over local areas at about the same time each morning and evening.
The six were the largest number of Western hamsats sent to space at one time. It was the biggest single proliferation since 1981 when USSR hams had sent up six in one flight. Here's the story on each of the microsats:
1990: UoSAT-OSCARs 14 and 15
By the end of the 1980s, University of Surrey space enthusiasts had a complex new satellite, UoSAT-C, ready to go to space. In fact, it was scheduled for launch in 1988 on a U.S. rocket, but the flight was postponed. The UoSAT team wasn't able to locate a ride to space for the heavy UoSAT-C, but they did obtain a launch for a pair of lighter satellites on the Ariane ASAP test.
Due to ASAP weight limits, the functions of UoSAT-C had to be split between two lighter replacement satellites-UoSAT-D and UoSAT-E.
Fortunately, UoSAT-C had been loaded with modules which could be pulled apart quickly to take advantage of the short-notice Ariane opportunity. Many mechanical and electrical parts of UoSAT-C were taken apart and reassembled. The UoSAT-C framework was shelved.
UoSAT-D and UoSAT-E were matching frameworks outfitted with identical housekeeping computer systems, but otherwise housing different electronic payloads. They would be low-orbit pacsats with message handling. They would study space radiation and its effects on semiconductors, develop a low-cost computerized spacecraft attitude control for precise Earth pointing, and photograph Earth with a low-cost charge-coupled device (CCD) television camera.
UoSAT-D and UoSAT-E were attached to the ASAP and launched January 22, 1990, alongside the four AMSAT microsats.
UoSAT-D was renamed UoSAT-OSCAR-14 (UO-14). It also has been called UoSAT-3.
UoSAT-E was renamed UoSAT-OSCAR-15 (UO-15). It also has been called UoSAT-4.
Surrey hams successfully commanded UO-14 and UO-15 on during their first day in space. Later that day, each spacecraft's computer software was sent up by radio to the satellites. Nominal telemetry was received from both hamsats.
Unfortunately, news turned bad 25 hours later when no UO-15 signals were received at Surrey.
Operators repeatedly transmitted commands to activate its redundant systems, with no luck. They tried for months to hear something, but no signals have been received since then from UO-15.
Stanford University had helped Surrey back in 1982, transmitting a strong signal to UO-9 to overcome blockage of that satellite's command receiver. Stanford hams tried again in 1990 to come to the rescue, using the same 150-ft. antenna with sophisticated digital signal processing equipment to look for an extremely weak signal from UO-15 oscillators. The big dish was able to hear UO-14 oscillators, but nothing from UO-15.
Attempts to restart UO-15 were abandoned. U.S. government radar continues to track the satellite, orbiting a mile or so higher than UO-14, amidst the pack of microsats launched January 22, 1990. UO-15 is simply dead in orbit.
The loss of UO-15 was mitigated by the good news from UO-14 which worked well. The tragedy spurred UoSAT to build a new small satellite, UoSAT-F, which was launched in 1991.
Meanwhile, UO-14 was working well in orbit handling lots of electronic-mail messages.
UO-14 has three computers for housekeeping and packet radio, including a 16-bit microprocessor with 4.5 megabytes of RAM. Four megabytes are used for bbs message storage.
The satellite's digital transponder receives at 145 MHz and transmits at 435 MHz. Ten watts of transmitter power make the satellite usable by small portable ground stations. Telemetry data packets are beaconed near 435 MHz.
UO-14 is an Earth-pointing satellite with a gravity-gradient boom and computer-controlled magnetorquing, an ideal system for small satellites in low-Earth orbit because it has no continuously-moving parts and expends no fuel.
To calculate its attitude, UO-14 carries a flux-gate magnetometer measuring Earth's geomagnetic field in the satellite's three axes.
Electricity is generated by gallium-arsenide solar arrays feeding nickel-cadmium rechargeable batteries. The satellite rotates slowly, distributing the Sun's light and heat evenly across the satellite.
Pacsats regularly relay messages around the globe to terrestrial packet networks in many regions. 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 1991, radio amateurs in Alaska and California created a gateway offering same-day delivery of dozens of messages to Alaska from the Lower 48 states. That success brought gateways to every continent. Today, scores of gateways cover North and South America, the Caribbean, Europe, the Middle East, South Africa, Oceania, Asia and even Baffin Island above the Arctic Circle. They deliver messages and responses within 24 hours. Such fast action is important in health-and-welfare traffic during emergencies and natural disasters.
In 1992, the first medical image transmitted via hamsat showed a fractured hip repaired with a compression hip screw. The hip had been pictured by a portable fluoroscopy X-ray displaying real-time images on a TV monitor for a physician during surgery. The image was stored on computer disk and transmitted to UO-14. The satellite kept it in memory for a few days, then sent it back to Earth, proving hamsats can help remote clinics get assessments from specialists.
Some of the construction costs of UO-14 had been paid by an American organization known as Volunteers In Technical Assistance. The non-profit organization had a large library of data on farming, windmills, stoves, ovens and other useful non-military subjects which it wanted to send to development workers in remote areas via UO-14's store-and-forward mailbox.
For a time, radio amateurs and VITA shared UO-14's transmitter, computer and 400-message memory. To accommodate both amateur and non-amateur users, the satellite switched back and forth between amateur and non-amateur frequencies.
When UO-14 transmitted on its non-amateur frequency, it was sending technical information to areas of the developing world poorly served by existing data communications. Such traffic was considered inappropriate for amateur channels. When the transmitter switches occurred, amateurs lost reception from their satellite for periods from a quarter-second to five seconds.
UO-14's uplink became congested with users. When 200 stations began using the satellite regularly, the satellite's 400 message limit was reached frequently. Amateur stations were limiting access for non-amateur VITA stations. After the British hamsat UO-22 was launched in 1991, Surrey decided to change UO-14's mission.
Amateur radio service was dropped. UO-14 stopped transmitting on its amateur frequency. Ham operations were moved to the new UO-22.
Today, UO-14's electronic mailbox links VITA with inexpensive, portable ground stations built around a computer, radio, battery and antenna. A ground station fits in a suitcase and works where no power lines exist. The pacsat is low enough for small ground stations to use simple whip antennas, made from coat hangers if necessary, to hear the satellite.
UO-14's bbs memory holds four million characters of information. When the satellite is overhead, a ground station can send up a message at 500 characters per second. During the few minutes the satellite is overhead, a ground station might send up 200,000 characters of information-equivalent to ten magazine articles.
Even if mail were picked up immediately by a recipient the next time the satellite passed over his head, it might be stored in the satellite from a few seconds up to twelve hours. Mail can stay in the satellite for days, of course, awaiting radio commands from an addressee.
A busy operator on the ground can put his satellite station on autopilot. He programs his computer to determine when the satellite will 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 the appointed hour, the ground-station computer would fire up its radio 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 and turn off its radio as the satellite passed out of sight over the horizon.
A pacsat like UO-14 and others makes it cheap and easy to send messages, data and images in or out of developing regions. Scores of portable ground stations already are linking underdeveloped countries to medical, weather, agriculture and engineering databanks.
Volunteers in Africa, Asia and South America use portable ground stations to ask for technical assistance. Travelers in the most rugged terrain receive data. Relief workers communicate directly with emergency teams at natural disaster sites.
Among the microsatellites launched January 22, 1990, was a small spacecraft known before launch as PACSAT-NA and after launch as AO-16 for AMSAT-OSCAR-16.
AMSAT ground controllers had no trouble commanding AO-16 on the air shortly after launch. The packet telemetry beacon was strong enough to be received easily with handheld radios using small, flexible, rubber-covered antennas. The message bbs was turned on in March 1990.
AO-16 downlink frequencies are near 437 and 2401 MHz. Uplink frequencies are near 145 MHz. Four packet stations on the ground can use the AO-16 bbs at one time.
The medical image of a fractured hip transmitted via UO-14 in 1992 also was relayed by AO-16. The Alaska-to-California message-traffic gateway created in 1991 used AO-16.
In 2001, AO-16 was semi-operational with its digipeater turned on. Uplink at 145 MHz. Downlink at 437 MHz. Beacon at 2401.1428 MHz. more info on AO-16
DOVE Peacetalker was among the best known of the microsats launched in January 1990. It certainly had the largest listening audience.
After launch to a low polar orbit alongside the other small satellites, DOVE Peacetalker was renamed DOVE-OSCAR-17. DOVE stands for Digital Orbiting Voice Encoder.
DO-17 was designed to educate the public about space by providing an easily-received satellite signal for demonstrations to children. DOVE was the first hamsat to transmit spoken messages promoting peace among nations.
The microsat had a digital recording system hooked to its receiver and a voice-synthesizer attached to its transmitter. School children around the globe were encouraged to write and speak messages which were transmitted to DOVE by Brazilian hams. DO-17 recorded the voices and then broadcast the messages on 145.825 MHz to be heard by anyone with an inexpensive vhf fm receiver or vhf scanner radio of the kind used to monitor police and fire calls.
The satellite offered students easy access to space research data. Its voice was programmed with various languages so students around the world could understand and learn as DOVE read out data from the satellite's sensors in synthesized speech.
No tracking was required to receive DO-17. Its signals were received using a standard pull-up whip antenna attached to a receiver or a flexible antenna on a portable receiver. A high outdoor antenna was even better than an indoor antenna.
Listening from 8 am to 1 pm and 7 pm to 12 midnight local time revealed the microsat flying overhead several times. When its 145.825 radio was on, it transmited for 2.5 minutes followed by an off period of 30 seconds during which it stood by for commands from the ground.
DOVE had beacons, but no active transponders. Besides 145 MHz, there was an S-band beacon relaying data in packet radio near 2401 MHz.
Many high schools collected telemetry data for science experiments. One California physics class monitored the rate at which DO-17 was spinning. It was supposed to be about three revolutions per minute (rpm). Analyzing telemetry sampled at intervals, the students understood the relationship between sample rate and spin rate. If the sample rate weren't fast enough, incorrect conclusions would have been drawn about rate and direction. Students concluded DOVE's spin rate had slowed.
A teacher's guide to using DO-17 with classroom exercises and experiments was available to schools from AMSAT Science Education Advisor, 421 N. Military, Dearborn, Michigan 48124 USA.
DO-17 is not operational. It stopped transmitting in March 1998 and no longer would respond to ground control stations.
Say "cheese" when you look up; you may be looking into the business end of a hamsat camera. WEBERsat-OSCAR-18, designed at Utah's Weber State University, has been snapping photos of Earth since shortly after it was lobbed to a 500-mi.-high polar orbit alongside the other AMSAT microsats on January 22, 1990.
WO-18 has a charge-coupled device (CCD) television camera which stores images in memory and compresses them into packet radio bursts transmitted to Earth.
One picture fills about 200k of computer memory, but the hamsat can send it down to the WSU ground station in as little as seven seconds.
WO-18 recorded such exotic locales as Ethiopia, the Bay of Bengal, Brazil, Africa's Lake Victoria, clouds over the Indian Ocean, Chile, the coastline of British Columbia near Vancouver Island, Australia, India, the coast of Peru, the U.S. Great Lakes, even the Moon, Sun and stars.
Wispy clouds in WO-18 pictures marked the possibility of satellite meteorology with very inexpensive imaging equipment.
WO-18 had a message bbs, a particle impact detector, a spectrometer, a magnetometer for navigation, an amateur television (atv) uplink receiver, and two downlink beacon transmitters. Its downlink was at 437 MHz.
WO-18 is not operational.
AMSAT-Argentina had been contemplating a satellite of its own in 1988 when news of the six-payload Ariane ASAP launch became known. The Argentines immediately joined North American AMSAT in the microsat project.
The letters LU are an amateur radio callsign prefix for Argentina so the satellite was dubbed LUsat. It was licensed in Argentina and paid for by Argentines, but constructed in Utah at CAST.
In orbit, it was renamed LUsat-OSCAR-19. Commanded in space from Argentina, LO-19 is a pacsat with digital message bbs available for non-profit use by hams around the globe.
The first message sent to the bbs was from Carlos Saul Menem, president of the Argentine Republic and a ham operator himself.
The uplink was at 145 MHz and the downlink at 437 MHz. One special telemetry beacon aboard LO-19 transmits data about the hamsat in easy-to-read 12 words-per-minute Morse code at 437.125 MHz. LO-19 broadcasts news bulletins continuously on Mondays on another frequency near 437 MHz.
LO-19 and other hamsats relayed essential public-service communications after Hurricane Iniki leveled parts of Hawaii in 1992. Health and welfare messages from devastated areas were forwarded to anxious relatives around the globe.
In 2001, LO-19 was semi-operational. The CW beacon was sending eight telemetry channels and one status channel on 437.126 MHz. No BBS service was available. The digipeater was not active. more info on AO-16 and even more info
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