STS-37 Shuttle Amateur Radio Experiment II (SAREX II) Ham radio operators around the world have their rigs ready to make contact with astronauts flying at 17,500 miles per hour at an altitude 276 statute miles above the Earth's surface. The STS-37 Atlantis mission will carry the Gamma-Ray Observatory (GRO) for deployment into orbit, experimental "scooters" to be evaluated for use in Space Station Freedom assembly, and a Shuttle Amateur Radio Experiment (SAREX) setup. STS-37 is the fourth flight to carry an amateur radio experiment and this mission encompasses the most ambitious demonstrations so far in the space program. NASA has approved the use of amateur radio experiments during Shuttle flight for two reasons: to encourage public participation in the space program and to support educational opportunities offered by amateur radio voice and digital communications. Broadcast Capabilities The setup for STS-37 will include two capabilities that are eagerly anticipated -- packet and fast scan television (FSTV). Packet radio was first demonstrated in 1990 on STS-35 with great success and it will be used again on STS-37. A first-time effort will be a television uplink to the manned spacecraft using a broadcast-standard transmission format (fast scan television). Amateur radio operators hope to use this uplink to carry live video from crew members' families to the Shuttle. The SAREX II capability on STS-37 comprises FSTV and slow scan television (SSTV). The latter was used previously during Mission STS- 51F. A VHS Panasonic VCR/monitor was selected for slow and fast scan reception aboard the Shuttle. The home model has been painted and wrapped in copper foil to reduce flammability and electromagnetic interference. Packet radio is a digital transmission technique that enables collection and dissemination of a high volume of stored messages to and from orbit. During STS-35, there were 238 three-way contacts and 1600 two-way contacts during the unattended digital operation mode. A new antenna that was left in place without interference with on-orbit activities was installed for STS-35. Along with packet radio, the in- place antenna allowed operations for virtually the entire mission. Contacts The primary mission of the SAREX-II is communication with ten schools across the United States. From these contacts, hundreds of students and teachers will be directly involved in communication with astronauts during a Space Shuttle mission. A possibility exists for contact between Atlantis and Mir, the Soviet orbiting space station. Two opportunities were planned during the STS-35 mission but neither opportunity could be realized. At the time of the first opportunity Mir was docking with another Soviet spacecraft, and the second opportunity was not realized because Atlantis returned to Earth a day earlier than scheduled. During the astronauts' sleep periods and when no other SAREX activities are scheduled, equipment will be left on in packet robot mode. If time permits, the crew will set up SAREX to transmit SSTV using orbiter video cameras during the GRO satellite release and during the extravehicular activity (EVA). The GRO satellite release is scheduled for mission elapsed time (MET) 2/03:00 (2 days and 3 hours after launch) for 1 hour. The EVA is scheduled for MET 2/22:00 through MET 3/05:00. Equipment Configurations The configuration for STS-37 comprises a low power hand-held frequency modulation (FM) transceiver, a spare battery set, an interface module, a SAREX headset assembly, an equipment assembly cabinet, a TV camera and monitor, a payload general support computer, and an antenna capable of being mounted in one of the orbiter flight deck windows. The equipment assembly houses power supplies, an SSTV converter, a packet radio terminal node controller, and switches and displays necessary to control the equipment as well as connectors to connect it to other equipment in the configuration. The FSTV module contains a receiving radio frequency preamplifier and a video decoder that provides National Television Standards Committee video for SAREX-II. This configuration communicates with amateur stations with line of sight of the orbiter in one of four modes, e.g., voice, SSTV, data, or FSTV. The voice mode is operated in the attended mode; SSTV, data, or FSTV can be operated in either the attended or unattended mode. All on-orbit SAREX-II operations, except FSTV, are conducted in the 2- meter (144 to 146 MHz) Amateur Satellite Service band utilizing FM with a nominal frequency deviation of 3 kHz. FSTV will be uplinked in the 70-meter band by specially designated FSTV experiment stations. The FSTV experiment does not include a downlink transmission because of limitations of radiating radio frequency energy inside the Space Shuttle cabin. Ground Equipment An elaborate station setup is not required for making a 2-meter contact. An effective radiated power of no more than 100 watts will give excellent results if there is not a lot of other ground interference. A fixed vertical antenna mounted above obstructions will eliminate the need for elaborate orbit tracking and pointing. The vertical is very desirable because it has a good radiation pattern at low elevations where the majority of the Shuttle passes occur. High direction and high power greatly improve chances of making contact. Accurate tracking and pointing data for your station location is best provided by a computer satellite tracking program. If you have a computer or programmable calculator and need a tracking program, write to AMSAT Software Exchange, Box 27, Washington, DC 20044. The orbital parameters required by these programs are broadcast on W1AW bulletins and AMSAT nets. Crew Astronaut Ken Cameron, KB5AWP, the pilot for mission STS-37, has been a ham since 1984, even before he joined NASA. He is extremely enthusiastic about flying the SAREX-II aboard this flight and has encouraged his fellow crew members to become hams. All five astronauts now have their tickets. The other crew members are commander Steve Nagel, N5RAW; mission specialist Jerry Ross, N5SCW; mission specialist Linda Godwin, N5RAX; and mission specialist Jay Apt, N5QWL. Keplerian Element Set NOTE: This STS-37 Element set is posted elsewhere on this Bulletin Board. W1AW Voice Bulletins W1AW will be broadcasting daily bulletins with updated information on SAREX during the flight. Voice bulletins are transmitted daily at 0130 UTC and 0430 UTC on the following frequencies: Station 10m 15m 20m 40m 80m _______ ______ ______ ______ _____ _____ W1AW 28.590 21.390 14.290 7.290 3.990 AMSAT Net Operations Information will also be available from the AMSAT net. The net operates every day as follows: Sunday 1800-2100 UCT (international) 14.282 MHz USB Tuesday 0130-0300 UCT (USA) 3.840 MHz LSB SAREX Uplink/Downlink Frequencies Downlink/uplink frequencies for voice/packet/SSTV to be used on STS-37 mission can be programed on 2-meter FM transceivers as follows: Mode Downlink Uplink Frequency Frequency __________ __________ ____________________________________ Voice/SSTV 145.55 MHz 144.95 (primary), 144.91, 144.97 MHz Packet 145.51 MHz 144.91 (primary), 144.93, 144.99 MHz FSTV None 70 cm band Note that only stations with prior arrangements can uplink FSTV signals (special authorization is required from the Federal Communications Commission). In order to reduce the pileup on the uplink frequency, there are 3 uplink frequencies and they will be used at random. The astronaut crew will be transmitting on one station --145.55 MHz for voice and SSTV, and will be listening on the other frequencies listed. This "split" operation has been used successfully in an environment where large pileups are expected. There will be no simplex operation with SAREX on either voice or packet. Although packeteers are not accustomed to operation with a TX/RX offset, in this case it is the only way to connect to SAREX. If transmission is on 144.95 or 145.51 MHz, the only people receiving transmissions will be those other ham radio operators in the area trying to hear the Shuttle. SAREX Packet Operating Hints FULLDUP OFF DWAIT 0.1 - 0.5 seconds FRACK > 3.0 seconds C KB5AWP The packet call sign on board the Shuttle is KB5AWP (SSID=0). TNC should be in half-duplex mode (FULLDUP OFF) with CD active just as is done for normal VHF packet operation. Compensation for doppler shift will be worth the effort. The bandwidth of the SAREX radio is +/-4kHz, maximum doppler is around 3.3 kHz. If doppler is not compensated for, the chance for contact is best when the Shuttle is at peak elevation at your site. Use care with the setting of two of the TNC's timers: DWAIT and FRACK. DWAIT is the time interval after the carrier detect light goes on and before the transmitter turns on. Be sure that connect requests and ACKs are contained in the 3-second FUDtimer window. FRACK sets the time interval between transmissions. After the frame is set, the TNC waits for the FRACK time, and then waits for the card detect signal to drop, then waits DWAIT, and then tries again. The FRACK must be at least 3 seconds so that transmission does not occur when the robot's FUDtimer decides it is time for it to transmit -- if you are transmitting at the same time, you will miss any packets the Shuttle is addressing to you and you won't have a successful QSO. Note that DWAIT (how soon do I transmit?) and FRACK (then how long wait?) parameters and the need to stop transmitting so that a reply can be heard are the same as working a DXpedition pileup on HF. If a DX station has a pattern of listening for a few seconds (=FUDtimer) before transmitting, you may have better luck being the LAST station the crew hears after the din dies down. The differences are that (1) the robot is a computer and is very predictable and (2) the robot can be working several stations at one time. NASA select Video Broadcast The continental United States will receive NASA Select television, 24 hours a day through the mission via the following: SATCOM F2R Transponder 13 72 degrees west longitude 3960 MHz (video) 6.8 MHz (audio)