Ne primo numero de LoScrittoio.it, abbiamo pubblicato un articolo relativo ad un Progetto condotto dalla NASA durante il passaggio dello sciame delle Leonidi, il 18 Novembre 1999. Pubblichiamo adesso alcuni dati tecnici rilasciati dall'Ente Spaziale americano in relazione al lancio del pallone sonda nonché al ricevitore VLF ed Il downlink dei dati.

Per maggiori informazioni sul progetto Leonidi visitare il sito: http://www.leonidslive.com

Balloon Launch

Date: Wednesday, November 18, 1999

Time: 00:30 CST, 06:30 UT

Location: The Atmospheric Research Facility (ARF) on the Marshall
Space Flight Center (MSFC)
Campus Huntsville, Alabama
34 38.769" North
86 40.766" West
657' MSL altitude

Maximum Altitude: Approximately 100,000 feet

Projected Landing: Approximately 127 miles ENE (075 true bearing) of the launch site: 35 06.90 North 30.52 West
This position is approximately two (2) miles east of the intersection of Highway 64 and Highway 30, near Ocoee Lake in the Little Frog Wilderness area, Tennessee

Profile: Climb to Max Altitude: 199 minutes
Descent: 21 minutes

ATV: 426.25 mHz transmit frequency (Cable Ready TV Channel 58) "Little Wheel" Horizontally Polarized Antenna. A video
overlay will contain longitude, latitude, altitude (meters), GPS time, heading, speed, video pointing direction, three (3)telemetry verification symbols, and the amateur radio call sign:

Upper Left:
Latitude (degrees & minutes)
Longitude (degrees & minutes)

Upper Right:
Heading (degrees)
Speed (Knots)

Lower Left:
GPS Time (UTC)
Altitude (meters)

Lower Right:
Call Sign (KE4ROC) & Telemetry Verification Symbols:
Block #1: LEFT ARROW if Latitude trap exceeded
Block #2: RIGHT ARROW if Longitude trap
exceeded
Block #3: SOLID BLOCK if below ascent altitude
Block #3: UP ARROW if above ascent altitude
Block #3: DOWN ARROW if below descent altitude
Pointing Direction (degrees)

VLF Radio Receiver: A VLF radio receiver (< 10kHz) will be listening for sferics, tweeks, whistlers, chorus, etc.. The audio will be down-linked on the ATV audio carrier (above). For more information see Project Inspire Web Pages "http://image.gsfc.nasa.gov/poetry/inspire/index.html"

Tracking Beacon: A long duration (7 to 10 day) very low power beacon will operate at 28.8 mHz, with a harmonic receivable at 144.0 mHz.

Telemetry: 1200 baud, AX.25 packet data on 144.39 mHz FM. Short (approximately 6") "Rubber-ducky" vertical antenna. The packet transmissions will be identified by the amateur call sign KE4ROC-11.

Telemetry Decoding: GPS location data will be transmitted every 60 seconds in the NEMA $GPGGA string. A thirty four (34) byte telemetry packet conforming to the APRS Telemetry System Standard is transmitted every 69 seconds. There are five (5) Analog-to-digital converters (ADC), and eight (8) digital "bit-switches". The digital switches are simply on/off(1 is OFF, 0 is ON), while the actual data from the ADC's may be calculated by the equation(s): A*X^2 + B*X + C. The actual coefficients A, B, and C for each ADC channel, and the telemetry parameters being down-linked are as follows:

ADC #1: A=0, B=0.0588, C=0 (Units: VOLTS, DC)
ADC #2: A=0, B=1.96, C=-272.6 (Units: degrees "C")
ADC #3: A=0, B=0.0735, C=-1.548 (Units: PSI)
ADC #4: A=0, B=1.96, C=-274.56 (Units: degrees "C")
ADC #5: A=0, B=1.96, C=-272.6 (Units: degrees "C")

ADC #1: Package Battery Voltage
ADC #2: Package Processor Board Temperature
ADC #3: Atmospheric Air Pressure
ADC #4: Outside Air Temperature (1)
ADC #5: Outside Air Temperature (2)

Digital #1: Payload cutdown Power
Digital #2: Test Light
Digital #3: Video Overlay Boards Power
Digital #4: Astrovid Video Camera Power
Digital #5: Latitude exceeded latitude trap
Digital #6: Longitude exceeded longitude trap
Digital #7: Altitude above ascent altitude
Digital #8: Altitude below descent altitude

Latitude
Trap: North of 34 55.0 N Latitude

Longitude
Trap: East of 085 13.0 W Longitude

Ascent
Altitude: 60,000 feet (18,703 meters)

Descent
Altitude: 65,000 feet (20,262 meters)