Interpretation of the N2 LBH glow observed on the S3-4 spacecraft

Emissions in the vacuum ultraviolet Lyman-Birge-Hopfield (LBH) bands of N2 were observed at night from the S3-4 spacecraft and from the Space Shuttle. No atmospheric source of this emission was identified. Conway et al. have reported that the intensity of the S3-4 LBH emission varied as the cube power of the N2 or N2O concentration. A vehicle-atmosphere interaction was suggested as the source but it was found that the needed excitation cross section would have to be unacceptably large. Recent models of the gas concentration build-up around large space vehicles predict concentrations that may be consistent with the observe LBH intensity variation with altitude. The emission in the model is generated primarily by secondary collisional excitation by ambient N2 and/or O of desorbed metastable molecular constituents. A Chapman-like production function in the induced gaseous environment results in the observed cube power of the N2 concentration altitude variation. A cross section of approximately 2.5 x 10(-18) sq cm is required for excitation of desorbed metastable N2(A) to the N2 (a 1 Pi g) state to account for the observed intensities

A possible glow experiment for the EOM 1-2 mission

A possible opportunity for study of surface glow exists during the Environmental Observation Mission (EOM) 1-2 mission scheduled for launch on September 3, 1986. The EOM 1-2 payload includes spectroscopic and photometric instruments which operate in wavelength regions of great interest to the glow assessment activity. However, as in the case of many remote sensing instruments, these are located in the payload bay in such a way as to avoid viewing any shuttle or payload surfaces. If these instruments are to measure the spectral characteristics of surfaces, it is necessary for such surfaces to be positioned in the field of view of these instruments for the duration of the particular measurement sequence. It is possible that the shuttle of which the EOM 1-2 payload flies will have an Remote Manipulator System (RMS) in place. An assessment has shown that it is indeed feasible to place a four-sided cuff around the end of the RMS. The four sides, each coated with a different material, can then be positioned in turn above the instruments, and in such a way that the surface is alternately pointed into the ram and into the wake

The UV-VIS optical environment of the shuttle

During the Spacelab 1 shuttle mission, spectroscopic measurements were made of the atmospheric emissions over a broad wavelength range extending from the extreme ultraviolet to the near infrared. Those measurements were made under a variety of vehicle attitude and sunlight conditions. Superimposed on such spectra would be any features associated with the induced vehicle environment and its interaction with solar photons and the ambient neutral atmosphere and plasma. Various anomalies and unexpected features in the spectra from the perspective of possible shuttle-induced origins are discussed. The data indicate a dramatic cleanup of the vehicle environment over the course of the 10-day mission, a strong non-atmospheric red continuum underlying the spectra at night and at large angles to the velocity vector, and a variety of molecular band distributions which are not explained by the present understanding of the atmosphere

An Imaging Spectrometric Observatory (ISO)

The Imaging Spectrometric Observatory (ISO) is designed for low light level spectroscopy of both the day and night side of the earth. The instrument is composed of five spectrometers, each of which covers part of the total wavelength range of 30 to 1300 nm spanned by the instrument. Wavelength resolution varies between 0.2 and 0.6 nm over the spectral range. The five spectrometers are each optimized for a portion of the spectrum by the choice of mirror reflective coatings and detector photocathode materials. The full spectral range for each spectrometer is covered in a total of 11 grating steps. The Imaging Spectrometric Observatory was flown for the first time on the Spacelab 1 mission during which it acquired almost 40 hr of observations. The ISO investigation to be flown on the Atmospheric Laboratory for Applications and Science (ATLAS 1) mission will draw on the experience gained from the data gathered on Spacelab 1. The detector system in each spectrometer was upgraded to provide both higher sensitivity at low light levels and simultaneous imaging over larger spectral segments than was achieved on Spacelab 1. In addition, the instrument and the observing sequences were modified to allow observation of the sun in the extreme ultraviolet. A summary of ISO parameters for ATLAS 1 (scheduled for late 1990) is given

Enhanced N(+) Sub 2 in the Shuttle Environment

Observations were made of the N2 first negative and Meinel emission bands with the Imaging Spectrometric Observatory (ISO) on Spacelab 1. These observations have revealed the presence of N2 emissions which exceed those expected on the basis of current ionospheric models by up to a factor of 10. If the emission is of terrestrial origin, large unidentified ionospheric sources of N2 ions must exist. On the other hand, if the source is local to the shuttle environment, a mechanism must be found which is capable of generating emissions of such unexpectedly large intensity. Charge exchange of ambient ionospheric O+ ions with shuttle environmental N2, followed by resonance scattering of sunlight, as a candidate were suggested. However, this model implies that a cloud of N2 gases must surround the vehicle in concentrations in excess of 10 to the 11 c.c. cm with a scale length of tens of meters. In addition, the N2 residence time must be of the order of 10 sec

A Search for N2+ in Spectra of Comet C/2002C1 (Ikeya-Zhang)

We report low- and high-resolution spectra of comet C/2002 C1 (Ikeya-Zhang) from McDonald Observatory. The comet had a well-developed ion tail including CO+, CO2+, CH+, and H2O+. We used our high-resolution spectra to search for N2+. None was detected and we placed upper limits on N2+/CO+ of 5.4 times 10^{-4}. N2+ was detected in the low-resolution spectra but we show that this emission was probably telluric in origin (if cometary, we derive N2+/CO+ = 5.5 times 10^{-3}, still very low). We discuss the implications for the conditions in the early solar nebula of the non-detection of N2+. These depend on whether the H2O ice was deposited in the amorphous or crystalline form. If H2O was deposited in its crystalline form, the detection of CO+ but not N2+ has implications for H2O/H2 in the early solar nebula.Comment: Accepted for publication in ApJ (Letters) - 10 Sept 200

Technique to retrieve solar EUV flux and neutral thermospheric O, O2, N2, and temperature from airglow measurements

We describe a method for retrieving neutral thermospheric composition and solar EUV flux from optical measurements of the O(+)(P-2) 732 nm and O(D-1) 630 nm airglow emissions. The parameters retrieved are the neutral temperature, the O, L2, and N2 density profiles, and a scaling factor for the solar EUV flux spectrum. The temperature, solar EUV flux scaling factor, and atomic oxygen density are first retrieved from the 732 nm emission, which are then used with the 630 nm emission to retrieve the O2 and N2 densities. Between the altitudes of 200 and 400 km the retrieval technique is able to statistically retrieve values to within 3.1% for thermospheric temperature, 3.3% for atomic oxygen, 2.3% for molecular oxygen, and 2.4% for molecular nitrogen. The solar EUV flux scaling factor has a retrieval error of 5.1%. We also present the results of retrievals using existing data taken from both groundbased and spacebased instruments. These include airglow data taken by the Visible Airglow Experiment on the Atmospheric Explorer spacecraft and the Imaging Spectrometric Observatory flown on the ATLAS 1 shuttle mission in 1992

A Study of Space Station Contamination Effects

A workshop was held with the specific objective of reviewing the state-of-knowledge regarding Space Station contamination, the extent to which the various categories of contamination can be predicted, and the extent to which the predicted levels would interfere with onboard scientific investigations or space station functions. The papers presented at the workshop are compiled and address the following topics: natural environment, plasma electromagnetic environment, optical environment, particulate environment, spacecraft contamination, surface physics processes, laboratory experiments and vented chemicals/contaminants

How do tsetse recognise their hosts? The role of shape in the responses of tsetse (Glossina fuscipes and G. palpalis) to artificial hosts

Palpalis-group tsetse, particularly the subspecies of Glossina palpalis and G. fuscipes, are the most important transmitters of human African trypanomiasis (HAT), transmitting .95% of cases. Traps and insecticide-treated targets are used to control tsetse but more cost-effective baits might be developed through a better understanding of the fly’s host-seeking behaviour.Electrocuting grids were used to assess the numbers of G. palpalis palpalis and G. fuscipes quanzensis attracted to and landing on square or oblong targets of black cloth varying in size from 0.01 m2 to 1.0 m2. For both species, increasing the size of a square target from 0.01 m2 (dimensions = 0.1 x 0.1 m) to 1.0 m2 (1.0 x 1.0 m) increased the catch ,4x however the numbers of tsetse killed per unit area of target declined with target size suggesting that the most cost efficient targets are not the largest. For G. f. quanzensis, horizontal oblongs, (1 m wide x 0.5 m high) caught, 1.8x more tsetse than vertical ones (0.5 m wide x 1.0 m high) but the opposite applied for G. p. palpalis. Shape preference was consistent over the range of target sizes. For G. p. palpalis square targets caught as many tsetse as the oblong; while the evidence is less strong the same appears to apply to G. f. quanzensis. The results suggest that targets used to control G. p. palpalis and G. f. quanzensis should be square, and that the most cost-effective designs, as judged by the numbers of tsetse caught per area of target, are likely to be in the region of 0.25 x 0.25 m2. The preference of G. p. palpalis for vertical oblongs is unique amongst tsetse species, and it is suggested that this response might be related to its anthropophagic behaviour and hence importance as a vector of HAT