MULTIFOT was a campaign involving a scientific rocket payload, a ground based multichannel photometer and a sodium lidar. The main purpose was to make a simultaneous measurements of the vertical profiles of a number of oxygen-related airglow emissions and the Na vertical density profile.
The payload contained 6 forward-looking and 4 side-looking photometers, a pulsed plasma probe and a electron temperature probe. The 6 forward-looking photometers were mounted in the first payload bay below the nose cone. In order to avoid heat conduction from the rocket body the complete 6 photometer unit was thermally insulated from the rest of the payload structure. The 4 side-looking photometers were mounted in the second and third payload bays, and viewed the atmosphere through 2" diameter quartz windows inserted into the payload skin. In the case of the side-looking photometers thermal insulation was achieved by mounting the photometers on bulkheads made from low-conductivity composite material.
The vehicle used was SONDA III sounding rocket developed by the Brazilian Institute for Space and Aeronautics (IAE). This is a two stage vehicle with a 30 cm diameter second stage, capable of carrying a payload of approximately 100 kg to 600 km altitude. The present experiment used a shortened version of the SONDA III vehicle which carried the 105 kg payload to an apogee of 282 km.
FLIGHT DATA Vehicle: SONDAIII Site: Alcântara Launch Center (2° S,44° W) Date: 31 May 1992 Time: 23:52 Local Standard Time (02:52 UT on 1 June 1992) Elevation angle at launcher: 82° Apogee: 282 km Horizontal range: 398 km Nose cone opening height: 68 km Spin rate: 4 s-¹ Mean zenith angle: 26.2° Precession cone angle: 6.8° Precession period: 14.7 s GEOPHYSICAL DATA FOR 31 MAY 1992 Ap: 8 Kp index (sum): 15+ F10.7 cm solar flux: 101.8
The photometers used in the payload are conventional in design, with an interference filter to select the emission line, and a lens and diaphragm to determine the field of view (FOV). In all photometers the photomultipliers (PMTs) are used in the photon counting mode, with Amptek 101 charge sensitive preamplifiers. Photometer signals were registered by 10 bit counters at a sample rate of 250/s, with each individual sample being telemetered to the tracking station.
The absolute sensitivities of the photometers were calibrated before launch using a MgO screen illuminated by a laboratory sub-standard light source (Eppley ES 8315 calibration lamp). A tiny tritium activated light source mounted on a rotating shutter also made it possible to make an in-flight check of the photometer dark noise. Calibration of the O2 Herzberg photometer was carried out at Stockholm University using a calibrated Deuterium lamp.
MULTIFOT ROCKET PHOTOMETER CHARACTERISTICS Emission WaveLength DL Sensitivity (Counts.s-¹ .R-¹ ) Forward-looking photometers O2 Herzberg I 275.0 14.3 191.0 OI 557.7 557.7 1.7 684.0 BG 576.8 11.0 220.2 NaD 589.0 1.7 326.9 OH(8-3) 724.3 1.9 143.9 O2A(0-0) 759.5 5.7 43.6 Side-looking photometers NaD 589.0 1.8 84.1 OI 630 629.9 1.6 21.6 OH(8-3) 724.3 1.8 41.4 BG 710.2 10.9 ---- Did not work!
GROUND-BASED AIRGLOW PHOTOMETER
The MULTI 2 six channel multicolor tilting filter photometer constructed at INPE has the capacity to measure the zenith intensity of OI 557.7 nm, NaD 598 nm, OI 630 nm, OH(9-4) band Q(775 nm) and R(772 nm) branches and the O2 Atmospheric (0-1) band at 866 nm. A photomultiplier with a GaAs cathode (Hamamatsu R943-02) is used to cover the large spectral region. The OH(9-4) rotational temperatures are obtained from the intensity ratio between the R and Q branch intensities of the OH(9-4) band. Since the rotational temperature indicates the ambient atmospheric temperature in the emission layer, a simultaneous measurements of the temperature and the OH(8-3) emission profile makes it possible to determine the height to which the temperature refers.
A major objective of the MULTIFOT campaign was the simultaneous determination of the vertical profiles of the NaD airglow emission and the Na density, an experiment which had never been carried out before. Measurements of the vertical profile of the atmospheric sodium density were made using the transportable lidar system PORTAL. The lidar includes a sodium vapor cell for calibration purposes. The equipment was installed at the launch site, 5 km from the ramp, and was operated throughout the campaign.
PORTAL SPECIFICATIONS Dye laser transmitter Receiver wavelength: 589 nm Fresnel Lens: 0.4 m² bandwidth: 6 pm bandwidth: 1 nm pulse length: 2 µ s ht. resolution: 250 m rep. rate: 1 pps efficiency: 1 %
INTEGRATED AIRGLOW INTENSITIES (R) AND OH(9-4) BAND ROTATIONAL TEMPERATURE Emission Ground-based Rocket-upleg Rocket-downleg O2 Hz I ----- 29 ± 3 31 ± 3 OI 5577 124 ± 3 123 ± 4 135 ± 4 NaD 32 ± 9 ----- 34 ± 2 OH(9-4) 590 ± 16 ----- ----- T_OH (K) 189 ± 3 ----- ----- OH(8-3) ----- ----- 568 ± 37 O2A(0-0) ----- ----- 4500 ± 60 O2A(0-1) 282 ± 6 ----- -----
Takahashi, H.; Clemesha, B. R.; Simonich, D. M.; Melo, S. M. L.; Eras, A.; Stegman, J; Witt, G.;
Rocket measurements of the equatorial airglow: MULTIFOT 92 Database,
J. Atmos. Terr. Phys., 58(16), 1943-1961, 1996.
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