The Electron Losses and Fields Investigation
| Satellite | Status | NORAD | Uplink | Downlink | Beacon | Mode | Callsign | Reports | Info | IARU freq coord | Telemetry Decoder |
|---|---|---|---|---|---|---|---|---|---|---|---|
| ELFIN-A | ACTIVE | 43617 | 437.450 | 9k6 FSK AX.25 | WJ2XNX | latest report | details | YES | |||
| ELFIN-B | ACTIVE | 43616 | 437.475 | 9k6 FSK AX.25 | WJ2XOX | latest report | details | YES |
The ELFIN mission is twofold. ELFIN provides essential training opportunities for UCLA students to become the next generation of experimental space scientists and engineers.
Equally important, we are advancing geospace research by developing new instrumentation to investigate the mechanisms responsible for electron and ion precipitation in Earth’s magnetosphere. ELFIN is being designed to operate for ~2 years. The first month of the mission consists of system checkouts. Following this period, ELFIN will spin-up to 20rpm to perform science operations for the remainder of the mission. At the mission conclusion, the spacecraft will be disabled and will deorbit within 25 years (less than 15 years typical).
3U CubeSat with mass ~3.5kg and 75cm stacer boom in midsection. Two antennas consisting of four deployable elements total. Antennas are made of fiberglass inlaid with beryllium copper. Antennas are placed at endcap of spacecraft, and the assembly is rotated 45deg relative to body axes. The antenna elements project from body plane at 30deg. Spacecraft is spin-stabilized at 20rpm. 1U allocated to science particle detectors and associated processing units; 1U associated with magnetometer & stacer boom; 1U associated with avionics, radios, and batteries.
Fluxgate Magnetometer
ELFIN’s Fluxgate Magnetometer (FGM) enables correlation of pitch angle information with energetic particle spectra by making 3-axis magnetic field measurements. Requirements for the FGM are shown in the tables below. UCLA has a long history with magnetometer design, and the FGM is based on a previously delivered magnetometer.
ADCS
Two torquer coils, comprised of aluminum wire on plastic spools, provide spin and precession capability to ELFIN. Periodic (daily/weekly) scheduled maneuvers are executed with these coils using onboard control laws and a magnetoresistive magnetometer. Coarse sun sensors and a fine sun sensor, as well as the fluxgate magnetometer, provide supplementary Data for ground based attitude determination.
Communications
ELFIN has applied for allocation as amateur experimental:
– 9k6 / 19k2 GFSK UHF downlink and international beacons
– 9k6 VHF uplink
An Astrodev He-82 (modified form factor of the He-100) transmits and receives using two bent dipoles antennas deployed out of the 3U+ “tuna can” volume. These elements are made from magnetically clean fiberglass tape springs (with Beryllium copper Inlays)
Power
The magnetically clean solar panels contain 20 total UTJ cells that are arranged in opposing pairs and distributed along the 3U faces. The body mounted panels mean only some cells will be illuminated at a time for a given attitude. Two power boards, equipped with PIC microcontrollers, manage the four Lithium-ion batteries (18650 2.2Ah each) and provide +5V for the spacecraft bus.
ELFIN-A
ELFIN-A transmits 9600 baud beacons on 437.450 MHz with the FCC experimental call sign – WJ2XNX. It is currently in “early orbit mode”, beaconing every 34 sec.
ELFIN-A RF spectrum
48k audio WAV file ELFIN-A (3 beacons)
ELFIN-A High-Speed SoundModem by UZ7HO – Ver 0.18b – FSK G3RUH 9600bd
2018-09-17 20:57:21.850 UTC: from WJ2XNX to W6YRA9 (UI, payload: 254 byte) 000 > C0 00 AE 6C B2 A4 82 72 60 AE 94 64 B0 9C B0 E1 03 F0 93 0E 020 > 07 70 00 00 01 03 06 34 36 01 D7 01 FA 01 A2 00 02 02 C1 03 040 > 08 03 0E 03 11 03 0C 00 00 00 09 01 87 1B 80 66 80 00 8B 14 060 > 4F 01 B0 1B 40 66 20 01 0B 1C 3E 00 08 10 80 17 00 17 80 16 080 > 00 10 10 64 64 00 01 03 06 25 09 01 D8 02 06 01 98 00 02 02 100 > B9 02 FF 03 07 03 09 02 FF 00 00 00 08 00 48 1B 20 66 A0 00 120 > 7E 1E 98 FF 71 1B 40 66 20 00 7E 16 27 93 00 08 15 80 11 80 140 > 15 80 00 00 18 18 12 12 00 01 03 06 34 46 FF D6 00 43 00 67 160 > FF A4 FF 98 00 31 18 80 13 00 12 00 10 80 00 01 03 06 35 23 180 > FF E4 FF D6 00 71 FF AD FF 95 FF A4 16 80 11 80 12 00 13 80 200 > 19 00 B6 03 3D 00 F3 0C DD 20 00 00 00 1B B9 00 00 01 07 09 220 > 0F 00 70 2D 5C 00 00 AC B7 00 91 00 00 00 00 07 00 00 00 00 240 > 02 00 00 00 00 07 00 00 00 00 02 00 00 00 00 07 00 00 00 00 260 > 02 00 00 00 00 07 65 6C 66 61 49 5E C0
ELFIN-B
ELFIN-B transmits 9600 baud beacons on 437.475 MHz with the FCC experimental call sign – WJ2XOX. It is currently in “early orbit mode”, beaconing every 41 sec.
ELFIN-B RF spectrum
48k audio WAV file ELFIN-B (3 beacons)
ELFIN-B High-Speed SoundModem by UZ7HO – Ver 0.18b – FSK G3RUH 9600bd
2018-09-17 04:07:15.560 UTC: from WJ2XOX to W6YRA9 (UI, payload: 255 byte) 000 > C0 00 AE 6C B2 A4 82 72 60 AE 94 64 B0 9E B0 E1 03 F0 93 11 020 > 07 70 00 00 01 02 13 45 53 01 6A 01 92 00 61 00 02 02 7F 02 040 > DD 02 EB 02 DA 01 29 00 00 00 12 08 A5 28 80 60 20 0A 7D 01 060 > B1 07 6C 28 60 5D A0 FD 02 01 E4 00 09 10 70 21 80 25 B0 21 080 > E0 01 01 01 01 00 01 02 13 36 35 01 76 01 97 01 97 00 02 02 100 > 88 02 D7 02 E0 02 E6 02 DF 00 00 00 11 03 13 29 E0 27 5E DB 120 > DC 03 36 01 EC FE 7C 29 20 27 5E 20 0C 5B DD 3B 00 0A 22 40 140 > 13 20 1C 20 00 00 01 01 57 57 00 01 02 13 46 03 00 CE 00 30 160 > 00 13 01 01 01 01 01 01 05 80 01 01 18 80 08 80 00 01 02 13 180 > 46 38 00 1A 00 19 00 5C 01 01 01 01 01 01 05 80 01 01 1A 80 200 > 0B 00 1A 00 C5 03 CB 00 39 62 1B 19 00 03 00 11 14 00 00 00 220 > 06 06 0C 00 6E B3 2D 00 00 10 5B 00 91 00 00 00 00 07 00 00 240 > 00 00 02 00 00 00 00 07 00 00 00 00 02 00 00 00 00 07 00 00 260 > 00 00 02 00 00 00 00 07 65 6C 66 62 CE 5E C0
The HSKP telemetry is only fetched every 9 minutes, but the counters update roughly every 30 sec. So mostly the telemetry is unchanged throughout the passes.