ISSN:0048-6604    

DOI:10.1029/RS008i004p00261

年代:1973

数据来源: WILEY

摘要:

A short description is presented of the general scientific objectives of the Atmosphere Explorer mission.

ISSN:0048-6604    

DOI:10.1029/RS008i004p00263

年代:1973

数据来源: WILEY

摘要:

A short description is presented of the design goals, the spacecraft, and the data system and analysis concept for the Atmosphere Explorer mission.

ISSN:0048-6604    

DOI:10.1029/RS008i004p00267

年代:1973

数据来源: WILEY

摘要:

The open‐source mass spectrometer will be used to obtain the number densities of the neutral atmospheric gases in the mass range 1 to 48 amu at the satellite location. The ion source has been designed to allow gas particles to enter the ionizing region with the minimum practicable number of prior collisions with surfaces. This design minimizes the loss of atomic oxygen and other reactive species due to reactions with the walls of the ion source. The principal features of the open‐source spectrometer and the laboratory calibration system are discus

ISSN:0048-6604    

DOI:10.1029/RS008i004p00271

年代:1973

数据来源: WILEY

摘要:

The neutral‐atmosphere composition experiment instrumentation is designed to obtainin‐situmeasurements of neutral thermosphere composition from Atmosphere Explorer‐C, ‐D, and ‐E. The system is based on previously flown OGO‐6 and San Marco‐3 composition instruments. The mass‐spectrometer sensor includes a gold‐plated thermalizing chamber and ion source, a hyperbolic rod quadrupole analyzer, and an off‐axis electron multiplier. Automatic ion‐source sensitivity control and pulse‐counting techniques provide density measurement capability from approximately 125 to 1000 km altitude. The normal operating mode includes measurement at all masses in the range 1 to 44 amu with emphasis on hydrogen, helium, oxygen, nitrogen, and argon. Additional operational modes are optimized for minor constituent studies of any individual

ISSN:0048-6604    

DOI:10.1029/RS008i004p00277

年代:1973

数据来源: WILEY

摘要:

The determination of the temperature of the neutral gas at the location of the satellite is based on measurement of the velocity distribution of the molecular nitrogen. Measurement of the thermal‐velocity component in the presence of the free‐stream velocity will be obtained through application of the velocity‐scan technique and, independently, through use of a baffle technique. A 3‐cm diameter spherical sampling chamber with a 0.5‐cm diameter precisely‐knife‐edged orifice is located at the satellite equator to permit free diffusion of atmosphere gases between the chamber interior and the atmosphere. The spherical chamber is connected through a high‐conductance tube to a quadrupole mass‐spectrometer sensor to permit accurate quantitative evaluation of the density of the gas. The spectrometer, tuned to N2for most of the measuring time, will also be tuned to other gases for exploratory purposes. The accuracy of the temperature data is expected to be better than 5%. The altitude range, determined primarily by system snr at the upper altitudes and mean‐free‐path limitations at the lower altitudes, is expected to

ISSN:0048-6604    

DOI:10.1029/RS008i004p00287

年代:1973

数据来源: WILEY

摘要:

A triaxial‐accelerometer system will be included in each of the Atmosphere Explorer (AE) payloads. The instrument consists of three uniaxial miniature‐electrostatic‐accelerometer units mounted mutually at right angles. This paper provides a description of the accelerometer system being designed for AE. It includes the principles of the instrument operation, the measurement capabilities, and the relation between the measured data and the scientific and engineering results. The functions of the instrument are to determine the density of the neutral atmosphere, monitor the thrust of the orbit‐adjust propulsion system, determine the satellite minimum altitude, measure spacecraft roll, and provide some attitude‐sensing information. Measurements will be made four times per second or approximately once every 2 km of flight path. Density variations will be determined with an accuracy ranging from approximately 1% below 200 km to 10% at 350 km, not including any error in ephemeris or drag co

ISSN:0048-6604    

DOI:10.1029/RS008i004p00297

年代:1973

数据来源: WILEY

摘要:

Absolute pressure measurements are made by two instruments aboard Atmosphere Explorer (AE) : a cold‐cathode ion gauge and a capacitance manometer. The dual sensors feature coverage from 120 to 370 km with double coverage below 200 km, differing and complementary sensing techniques, usable output in the spinning and both normal and inverted despun satellite modes, simple formatting to facilitate data use for real‐time monitoring of spacecraft operation, and cross‐calibration in the laboratory and in

ISSN:0048-6604    

DOI:10.1029/RS008i004p00305

年代:1973

数据来源: WILEY

摘要:

The magnetic ion‐mass spectrometer is designed to measure the abundances of the ambient positive ions in the ionosphere. It will be calibrated in flight against the retarding‐potential analyzer and the cylindrical electrostatic probe to give absolute concentration data for the ion species detected. These parameters can be measured to approximately ±10% in well‐behaved regions where concentrations are above 103cm−3. However, in highly structured polar regions, some degradation in accuracy may be expected.Three mass ranges, covered simultaneously by the scan of the instrument, 1 to 4, 4 to 16, and 16 to 64 amu, permit measurement of the entire mass range, 1 to 64 amu, in 1 sec in the main (peaks) mode. An alternate mode, analog‐long, will extend the mass range to 90 amu with a 9‐sec period. Capability is provided to lock onto any set of mass numbers in the ratio 1:4:16 to give very high spatial resolution, e.g., 500, 250, and 125 m in the low‐, mid‐, and high‐mass ranges, respectively. This mode will be most useful in the despun satellite orientation to provide fine‐structure data on ion concentrations. In the spinning mode the phase shifts between roll modulation maxima of heavy and light ions determine the vertical component of the individual ion‐drift velocities. Values from a few km sec−1to over 20 km sec−1can be determined. Such data are applicable to the stu

ISSN:0048-6604    

DOI:10.1029/RS008i004p00315

年代:1973

数据来源: WILEY

摘要:

The Bennett spectrometer to be flown on Atmosphere Explorer‐C and ‐E (AE‐C and AE‐E) is designed to measure, throughout the 120 to 4000‐km orbit, the concentrations of all thermal positive ions in the mass range 1 to 72 amu and number density range 5 to 5 × 106ions cm−3. To reduce the buildup of ram pressure and facilitate measurements at low altitude, the analyzer is vented, and a multigrid ion‐current collector is employed. An extensive command capability permits optimization of instrument parameters for particular measurement objectives; commandable functions include mass‐scan range and period, the sensitivity‐resolution characteristic of the analyzer, orifice potential, and in‐flight calibration. Any combination of three mass ranges (1 to 4, 2 to 18, 8 to 72 amu) may be selected as the mass‐scan mode; each range is normally scanned in 1.6 sec, corresponding to a distance of 12 km along the orbit. Ion spectra will be simultaneously telemetered in both analog and digital form; the digital data result from on‐board processing of the analog spectra and consist only of ion‐peak coordinates. The three overlapping mass ranges will enable in‐flight evaluation of mass discrimination within the ion analyzer. Verification of absolute instrument sensitivity will require correlation of the spectrometer data with results from the companion electrostatic probe and retarding‐potential analyzer. Such correlations should permit individual ion concentrations to be deter

ISSN:0048-6604    

DOI:10.1029/RS008i004p00323

年代:1973

数据来源: WILEY