Dynamics Explorer 2 - Revision history

Kennethmacalpine: Updated

2024-07-27T00:35:48Z

Updated

Kku: link remote sensing

2024-01-08T16:07:00Z

link remote sensing

← Previous revision		Revision as of 16:07, 8 January 2024
Line 63:		Line 63:

	=== Fabry-Pérot Interferometer (FPI) ===		=== Fabry-Pérot Interferometer (FPI) ===
	The [[Fabry–Pérot interferometer]] (FPI) was a high-resolution remote sensing instrument designed to measure the thermospheric temperature, meridional wind, and density of the following metastable atoms:[[Allotropes of oxygen\|atomic oxygen]] (singlet S and D) and the 2P state of ionic atomic oxygen. The FPI performed a wavelength analysis on the light detected from the thermospheric emission features by spatially scanning the interference fringe plane with a multichannel array detector. The wavelength analysis characterized the [[Doppler broadening\|Doppler line profile]] of the emitting species. A sequential altitude scan performed by a commandable horizon scan mirror provided a cross-sectional view of the thermodynamic and dynamic state of the thermosphere below the DE-2 orbit. The information obtained from this investigation was used to study the dynamic response of the thermosphere to the energy sources caused by magnetospheric electric fields and the absorption of solar ultraviolet light in the thermosphere. The instrument was based on the visible airglow experiment (VAE) used in the [[Explorer 55\|Atmospheric Explorer program]]. The addition of a scanning mirror, the Fabry–Pérot etalon, an image plane detector, and a calibration lamp were the principal differences. Interference filters isolated lines at (in [[Angstrom]]s) 5577, 6300, 7320, 5896, and 5200. The FPI had a field of view of 0.53° (half-cone angle). From 16 February 1982 to 11 September 1982 the DE-2 satellite was inverted and the FPI measured [[Galactic Emission Mapping\|galactic emissions]].<ref name="Experiment5">{{cite web \|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-05\|title=Experiment: Atmospheric Dynamics and Energetics Investigation\|publisher=NASA\|date=28 October 2021\|access-date=23 November 2021}} {{PD-notice}}</ref>		The [[Fabry–Pérot interferometer]] (FPI) was a high-resolution [[remote sensing]] instrument designed to measure the thermospheric temperature, meridional wind, and density of the following metastable atoms:[[Allotropes of oxygen\|atomic oxygen]] (singlet S and D) and the 2P state of ionic atomic oxygen. The FPI performed a wavelength analysis on the light detected from the thermospheric emission features by spatially scanning the interference fringe plane with a multichannel array detector. The wavelength analysis characterized the [[Doppler broadening\|Doppler line profile]] of the emitting species. A sequential altitude scan performed by a commandable horizon scan mirror provided a cross-sectional view of the thermodynamic and dynamic state of the thermosphere below the DE-2 orbit. The information obtained from this investigation was used to study the dynamic response of the thermosphere to the energy sources caused by magnetospheric electric fields and the absorption of solar ultraviolet light in the thermosphere. The instrument was based on the visible airglow experiment (VAE) used in the [[Explorer 55\|Atmospheric Explorer program]]. The addition of a scanning mirror, the Fabry–Pérot etalon, an image plane detector, and a calibration lamp were the principal differences. Interference filters isolated lines at (in [[Angstrom]]s) 5577, 6300, 7320, 5896, and 5200. The FPI had a field of view of 0.53° (half-cone angle). From 16 February 1982 to 11 September 1982 the DE-2 satellite was inverted and the FPI measured [[Galactic Emission Mapping\|galactic emissions]].<ref name="Experiment5">{{cite web \|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-05\|title=Experiment: Atmospheric Dynamics and Energetics Investigation\|publisher=NASA\|date=28 October 2021\|access-date=23 November 2021}} {{PD-notice}}</ref>

	=== Ion Drift Meter (IDM) ===		=== Ion Drift Meter (IDM) ===

No such user: Disambiguating links to Attitude control (link changed to three-axis stabilization) using DisamAssist.

2023-01-06T09:09:12Z

Disambiguating links to Attitude control (link changed to three-axis stabilization) using DisamAssist.

← Previous revision		Revision as of 09:09, 6 January 2023
Line 56:		Line 56:

	== Spacecraft ==		== Spacecraft ==
	The general form of the spacecraft was a short polygon of {{cvt\|137\|cm}} in diameter and {{cvt\|115\|cm}} high. The triaxial antennas were {{cvt\|23\|m}} tip-to-tip. One {{cvt\|6\|m}} boom was provided for remote measurements. The spacecraft weight was {{cvt\|420\|kg}}. Power was supplied by a solar cell array, which charged two 6-[[ampere hour]] [[Nickel–cadmium battery\|nickel-cadmium batteries]]. The spacecraft was [[~~Attitude~~ ~~control~~\|three-axis stabilized]] with the yaw axis aligned toward the center of the Earth to within 1°. The spin axis was normal to the orbit plane within 1° with a spin rate of one revolution per orbit. A single-axis scan platform was included in order to mount the low-altitude plasma instrument (1981-070B-08). The platform rotated about the spin axis. A pulse code modulation telemetry data system was used that operated in real time or in a [[tape recorder]] mode. Data were acquired on a science-problem-oriented basis, with closely coordinated operations of the various instruments, both satellites, and supportive experiments. Measurements were temporarily stored on tape recorders before transmission at an 8:1 playback-to-record ratio. Since commands were also stored in a command memory unit, spacecraft operations were not real time.<ref name="Display"/>		The general form of the spacecraft was a short polygon of {{cvt\|137\|cm}} in diameter and {{cvt\|115\|cm}} high. The triaxial antennas were {{cvt\|23\|m}} tip-to-tip. One {{cvt\|6\|m}} boom was provided for remote measurements. The spacecraft weight was {{cvt\|420\|kg}}. Power was supplied by a solar cell array, which charged two 6-[[ampere hour]] [[Nickel–cadmium battery\|nickel-cadmium batteries]]. The spacecraft was [[three-axis stabilization\|three-axis stabilized]] with the yaw axis aligned toward the center of the Earth to within 1°. The spin axis was normal to the orbit plane within 1° with a spin rate of one revolution per orbit. A single-axis scan platform was included in order to mount the low-altitude plasma instrument (1981-070B-08). The platform rotated about the spin axis. A pulse code modulation telemetry data system was used that operated in real time or in a [[tape recorder]] mode. Data were acquired on a science-problem-oriented basis, with closely coordinated operations of the various instruments, both satellites, and supportive experiments. Measurements were temporarily stored on tape recorders before transmission at an 8:1 playback-to-record ratio. Since commands were also stored in a command memory unit, spacecraft operations were not real time.<ref name="Display"/>

	== Experiments ==		== Experiments ==

Artem.G: rm redundant word

2022-03-28T11:07:00Z

rm redundant word

← Previous revision		Revision as of 11:07, 28 March 2022
Line 48:		Line 48:
	}}		}}

	'''Dynamics Explorer 2''' ('''DE-2''' or '''Explorer 63''') was a [[NASA]] ~~mission,~~ low-altitude mission, launched on 3 August 1981. It consisted of two satellites, DE-1 and DE-2, whose purpose was to investigate the interactions between [[Plasma (physics)\|plasmas]] in the [[magnetosphere]] and those in the [[ionosphere]]. The two satellites were launched together into [[Polar orbit\|polar coplanar orbit]]s, which allowed them to simultaneously observe the upper and lower parts of the atmosphere.<ref name="Display">{{cite web\|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1981-070B\|title=Display: Explorer 63 (DE-2) 1981-070B\|publisher=NASA\|date=28 October 2021\|access-date=23 November 2021}} {{PD-notice}}</ref>		'''Dynamics Explorer 2''' ('''DE-2''' or '''Explorer 63''') was a [[NASA]] low-altitude mission, launched on 3 August 1981. It consisted of two satellites, DE-1 and DE-2, whose purpose was to investigate the interactions between [[Plasma (physics)\|plasmas]] in the [[magnetosphere]] and those in the [[ionosphere]]. The two satellites were launched together into [[Polar orbit\|polar coplanar orbit]]s, which allowed them to simultaneously observe the upper and lower parts of the atmosphere.<ref name="Display">{{cite web\|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1981-070B\|title=Display: Explorer 63 (DE-2) 1981-070B\|publisher=NASA\|date=28 October 2021\|access-date=23 November 2021}} {{PD-notice}}</ref>

	== Mission ==		== Mission ==

ZI Jony: v2.04b - Fix errors for CW project (Template value ends with break)

2022-03-18T14:39:31Z

v2.04b - Fix errors for CW project (Template value ends with break)

← Previous revision		Revision as of 14:39, 18 March 2022
Line 4:		Line 4:
	{{Infobox spaceflight		{{Infobox spaceflight
	\| name = Dynamics Explorer 2		\| name = Dynamics Explorer 2
	\| names_list = Explorer 63<br/>Dynamics Explorer-B~~<br/>~~		\| names_list = Explorer 63<br/>Dynamics Explorer-B
	\| image = Dynamics_Explorer_1_and_2_(Explorer_62_and_Explorer_63).jpg		\| image = Dynamics_Explorer_1_and_2_(Explorer_62_and_Explorer_63).jpg
	\| image_caption = Dynamics Explorer 1 (Explorer 62) in the bottom and Dynamics Explorer 2 (Explorer 63) in the top		\| image_caption = Dynamics Explorer 1 (Explorer 62) in the bottom and Dynamics Explorer 2 (Explorer 63) in the top

Orenburg1: sp

2022-01-25T12:55:13Z

← Previous revision		Revision as of 12:55, 25 January 2022
Line 84:		Line 84:

	=== Neutral Atmosphere Composition Spectrometer (NACS) ===		=== Neutral Atmosphere Composition Spectrometer (NACS) ===
	The Neutral Atmosphere Composition Spectrometer (NACS) was designed to obtain in situ measurements of the neutral atmospheric composition and to study the variations of the neutral atmosphere in response to energy coupled into it from the magnetosphere. Because temperature enhancements, large-scale circulation cells, and wave propagation are produced by energy input (each of which ~~posseses~~ a specific signature in composition variation), the measurements permitted the study of the partition, flow, and deposition of energy from the magnetosphere. Specifically, the investigation objective was to characterize the composition of the neutral atmosphere with particular emphasis on variability in constituent densities driven by interactions in the atmosphere, ionosphere, and magnetosphere system. The quadrupole mass spectrometer used was nearly identical to those flown on the [[Explorer 51]] (AE-C), [[Explorer 54]] (AE-D), and [[Explorer 55]] (AE-E) missions. The electron-impact ion source was used in a closed mode. Atmospheric particles entered an antechamber through a knife-edged orifice, where they were thermalized to the instrument temperature. The ions with the selected charge-to-mass ratios had stable trajectories through the hyperbolic electric field, exited the analyzer, and entered the detection system. An off-axis beryllium-copper dynode multiplier operating at a gain of 2.E6 provided an output pulse of electrons for each ion arrival. The detector output had a pulse rate proportional to the neutral density in the ion source of the selected mass. The instrument also included two baffles that scanned across the input orifice for optional measurement of the zonal and vertical components of the neutral wind. The mass select system provided for 256 mass values between 0 and 51 atomic mass units (u) or each 0.2 unit. It was possible to call any one of these mass numbers into each of eight 0.016-second intervals. This sequence was repeated each 0.128 second.<ref name="Experiment3">{{cite web \|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-03\|title=Experiment: Neutral Atmosphere Composition Spectrometer (NACS)\|publisher=NASA\|date=28 October 2021\|access-date=23 November 2021}} {{PD-notice}}</ref>		The Neutral Atmosphere Composition Spectrometer (NACS) was designed to obtain in situ measurements of the neutral atmospheric composition and to study the variations of the neutral atmosphere in response to energy coupled into it from the magnetosphere. Because temperature enhancements, large-scale circulation cells, and wave propagation are produced by energy input (each of which possesses a specific signature in composition variation), the measurements permitted the study of the partition, flow, and deposition of energy from the magnetosphere. Specifically, the investigation objective was to characterize the composition of the neutral atmosphere with particular emphasis on variability in constituent densities driven by interactions in the atmosphere, ionosphere, and magnetosphere system. The quadrupole mass spectrometer used was nearly identical to those flown on the [[Explorer 51]] (AE-C), [[Explorer 54]] (AE-D), and [[Explorer 55]] (AE-E) missions. The electron-impact ion source was used in a closed mode. Atmospheric particles entered an antechamber through a knife-edged orifice, where they were thermalized to the instrument temperature. The ions with the selected charge-to-mass ratios had stable trajectories through the hyperbolic electric field, exited the analyzer, and entered the detection system. An off-axis beryllium-copper dynode multiplier operating at a gain of 2.E6 provided an output pulse of electrons for each ion arrival. The detector output had a pulse rate proportional to the neutral density in the ion source of the selected mass. The instrument also included two baffles that scanned across the input orifice for optional measurement of the zonal and vertical components of the neutral wind. The mass select system provided for 256 mass values between 0 and 51 atomic mass units (u) or each 0.2 unit. It was possible to call any one of these mass numbers into each of eight 0.016-second intervals. This sequence was repeated each 0.128 second.<ref name="Experiment3">{{cite web \|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-03\|title=Experiment: Neutral Atmosphere Composition Spectrometer (NACS)\|publisher=NASA\|date=28 October 2021\|access-date=23 November 2021}} {{PD-notice}}</ref>

	=== Neutral-Plasma Interactions Investigation ===		=== Neutral-Plasma Interactions Investigation ===

Wprlh: /* Retarding Potential Analyzer (RPA) */Fixed typo

2022-01-10T06:19:39Z

Retarding Potential Analyzer (RPA): Fixed typo

← Previous revision		Revision as of 06:19, 10 January 2022
Line 90:		Line 90:

	=== Retarding Potential Analyzer (RPA) ===		=== Retarding Potential Analyzer (RPA) ===
	The Retarding Potential Analyzer (RPA) measured the bulk ion velocity in the direction of the spacecraft motion, the constituent ion concentrations, and the ion temperature along the satellite path. These parameters were derived from a least squares fit to the ion number flux versus energy curve obtained by sweeping or stepping the voltage applied to the internal retarding grids of the RPA. In addition, a separate wide aperture sensor, a duct sensor, was flown to measure the spectral characteristics of ~~iregularities~~ in the total ion concentration. The measured parameters obtained from this investigation were important to the understanding of mechanisms that influence the plasma; i.e. to understand the coupling between the solar wind and the Earth's atmosphere. The measurements were made with a multigridded planar retarding potential analyzer very similar in concept and geometry to the instruments carried on the Atmospheric Explorer satellites. The retarding potential was variable in the range from approximately +32 to 0 [[volt]]s. The details of this voltage trace, and whether it was continuous or stepped, depended on the operating mode of the instrument. Specific parameters deduced from these measurements were ion temperature; vehicle potential; ram component of the ion drift velocity; the ion and electron concentration irregularity spectrum; and the concentration of H+, He+, O+, and Fe+, and of molecular ions near [[Apsis\|perigee]].<ref name="Experiment7">{{cite web\|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-07\|title=Experiment: Retarding Potential Analyzer (RPA)\|publisher=NASA\|date=28 October 2021\|access-date=24 November 2021}} {{PD-notice}}</ref>		The Retarding Potential Analyzer (RPA) measured the bulk ion velocity in the direction of the spacecraft motion, the constituent ion concentrations, and the ion temperature along the satellite path. These parameters were derived from a least squares fit to the ion number flux versus energy curve obtained by sweeping or stepping the voltage applied to the internal retarding grids of the RPA. In addition, a separate wide aperture sensor, a duct sensor, was flown to measure the spectral characteristics of irregularities in the total ion concentration. The measured parameters obtained from this investigation were important to the understanding of mechanisms that influence the plasma; i.e. to understand the coupling between the solar wind and the Earth's atmosphere. The measurements were made with a multigridded planar retarding potential analyzer very similar in concept and geometry to the instruments carried on the Atmospheric Explorer satellites. The retarding potential was variable in the range from approximately +32 to 0 [[volt]]s. The details of this voltage trace, and whether it was continuous or stepped, depended on the operating mode of the instrument. Specific parameters deduced from these measurements were ion temperature; vehicle potential; ram component of the ion drift velocity; the ion and electron concentration irregularity spectrum; and the concentration of H+, He+, O+, and Fe+, and of molecular ions near [[Apsis\|perigee]].<ref name="Experiment7">{{cite web\|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-07\|title=Experiment: Retarding Potential Analyzer (RPA)\|publisher=NASA\|date=28 October 2021\|access-date=24 November 2021}} {{PD-notice}}</ref>

	=== Vector Electric Field Instrument (VEFI) ===		=== Vector Electric Field Instrument (VEFI) ===

PohranicniStraze: sp

2022-01-10T03:55:58Z

← Previous revision		Revision as of 03:55, 10 January 2022
Line 66:		Line 66:

	=== Ion Drift Meter (IDM) ===		=== Ion Drift Meter (IDM) ===
	The [[Ion drift meter]] (IDM) measured the bulk motions of the ionospheric plasma perpendicular to the satellite velocity vector. The measured parameters, horizontal and vertical ion-drift velocities, had an expected range of ± {{cvt\|4\|km/s}}. The accuracy of the measurement was expected to be ± {{cvt\|50\|km/s}} for the anticipated 0.5° accuracy in vehicle attitude determination. The nominal time resolution of the measurement was 1/32 seconds. This investigation yielded information on: (1) the ion convection (electric field) pattern in the auroral and polar ionosphere; (2) the flow of plasma along magnetic field lines within the plasmasphere, which determines whether this motion was simply a breathing of the protonosphere, a refilling of this region after a storm, or an interhemispheric transport of plasma; (3) the thermal ion contribution to field-aligned electric currents; (4) velocity fields associated with small-scale phenomena that are important at both low and high latitudes; and (5) the magnitude and variation of the total concentration along the flight path. The ion drift meter measured the plasma motion parallel to the sensor face by using a gridded collimator and multiple collectors to determine the direction of arrival of the plasma. The instrument geometry was very similar to that used on the Atmospheric Explorer satellites. Each sensor consisted of a square entrance aperture that served as [[collimator]], some electrically isolating grids, and a segmented planar collector. The angle of arrival of the ions with respect to the sensor was determined by measuring the ratio of the currents to the different collector segments, and this was done by taking the difference in the [[Logarithm]]s of the current. Two techniques were used to determine this ratio. In the standard drift sensor (SDS), the collector segments were connected in pairs to two logarithmic amplifiers. The second technique, called the ~~univeral~~ drift sensor (UDS), allowed simultaneous measurement of both components. Here, each collector segment was permanently connected to a logarithmic amplifier and two difference amplifiers were used to determine the horizontal and vertical arrival angles simultaneously. The IDM consisted of two sensors, one providing the SDS output and the other providing the UDS output. During the period from 17 March 1981 to 7 May 1982 the instrument memory suffered a critical upset and ion temperatures and drifts are not available during this period. <ref name="Experiment6">{{cite web\|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-06\|title=Experiment: Ion Drift Meter (IDM)\|publisher=NASA\|date=28 October 2021\|access-date=23 November 2021}} {{PD-notice}}</ref>		The [[Ion drift meter]] (IDM) measured the bulk motions of the ionospheric plasma perpendicular to the satellite velocity vector. The measured parameters, horizontal and vertical ion-drift velocities, had an expected range of ± {{cvt\|4\|km/s}}. The accuracy of the measurement was expected to be ± {{cvt\|50\|km/s}} for the anticipated 0.5° accuracy in vehicle attitude determination. The nominal time resolution of the measurement was 1/32 seconds. This investigation yielded information on: (1) the ion convection (electric field) pattern in the auroral and polar ionosphere; (2) the flow of plasma along magnetic field lines within the plasmasphere, which determines whether this motion was simply a breathing of the protonosphere, a refilling of this region after a storm, or an interhemispheric transport of plasma; (3) the thermal ion contribution to field-aligned electric currents; (4) velocity fields associated with small-scale phenomena that are important at both low and high latitudes; and (5) the magnitude and variation of the total concentration along the flight path. The ion drift meter measured the plasma motion parallel to the sensor face by using a gridded collimator and multiple collectors to determine the direction of arrival of the plasma. The instrument geometry was very similar to that used on the Atmospheric Explorer satellites. Each sensor consisted of a square entrance aperture that served as [[collimator]], some electrically isolating grids, and a segmented planar collector. The angle of arrival of the ions with respect to the sensor was determined by measuring the ratio of the currents to the different collector segments, and this was done by taking the difference in the [[Logarithm]]s of the current. Two techniques were used to determine this ratio. In the standard drift sensor (SDS), the collector segments were connected in pairs to two logarithmic amplifiers. The second technique, called the universal drift sensor (UDS), allowed simultaneous measurement of both components. Here, each collector segment was permanently connected to a logarithmic amplifier and two difference amplifiers were used to determine the horizontal and vertical arrival angles simultaneously. The IDM consisted of two sensors, one providing the SDS output and the other providing the UDS output. During the period from 17 March 1981 to 7 May 1982 the instrument memory suffered a critical upset and ion temperatures and drifts are not available during this period. <ref name="Experiment6">{{cite web\|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-06\|title=Experiment: Ion Drift Meter (IDM)\|publisher=NASA\|date=28 October 2021\|access-date=23 November 2021}} {{PD-notice}}</ref>

	=== Langmuir Probe Instrument (LANG) ===		=== Langmuir Probe Instrument (LANG) ===

CRS-20: Updated

2021-11-26T01:05:40Z

Updated

← Previous revision		Revision as of 01:05, 26 November 2021
Line 44:		Line 44:

	\| programme = '''Explorer program'''		\| programme = '''Explorer program'''
	\| previous_mission = ~~Explorer 62 (~~[[Dynamics Explorer 1]])		\| previous_mission = [[Dynamics Explorer 1]] (Explorer 62)
	\| next_mission = [[Solar Mesosphere Explorer\|~~Explorer 64 (~~Solar Mesophere Explorer)]]		\| next_mission = [[Solar Mesosphere Explorer\|Solar Mesophere Explorer (Explorer 64)]]
	}}		}}

Rodw: Disambiguating links to Elf (disambiguation) (link changed to Extremely low frequency) using DisamAssist.

2021-11-24T10:42:30Z

Disambiguating links to Elf (disambiguation) (link changed to Extremely low frequency) using DisamAssist.

← Previous revision		Revision as of 10:42, 24 November 2021
Line 93:		Line 93:

	=== Vector Electric Field Instrument (VEFI) ===		=== Vector Electric Field Instrument (VEFI) ===
	The Vector Electric Field Instrument (VEFI) used flight-proven double-probe techniques with {{cvt\|20\|m}} baselines to obtain measurements of DC electric fields. This electric field investigation had the following objectives: (1) to obtain accurate and comprehensive triaxial DC electric field measurements at ionospheric altitudes in order to refine the basic spatial patterns, define the large-scale time history of these patterns, and study the small-scale temporal and spatial variations within the overall patterns; (2) to study the degree to which and in what region the electric field projects to the equatorial plane; (3) to obtain measurements of [[extremely low frequency]] ([[ELF]]) and lower frequency irregularity structures; and (4) to perform numerous correlative studies. The instrument consisted of six cylindrical elements {{cvt\|11\|m}} long and {{cvt\|2.8\|cm}} in diameter. Each antenna was insulated from the plasma except for the outer {{cvt\|2\|m}}. The baseline, or distance between the midpoints of these {{cvt\|2\|m}} active elements, was 20 m. The antennas were interlocked along the edges to prevent oscillation and to increase their rigidity against drag forces. The basic electronic system was very similar in concept to those used on [[Explorer 50]] (IMP-J) and [[ISEE-1]], but modified for a three-axis measurement on a nonspinning spacecraft. At the core of the system were the high-impedance (1.E12 [[ohm]]) preamplifiers, whose outputs were accurately subtracted and digitized (14-bit A/D conversion for sensitivity to about 0.1 microvolt/m) to maintain high resolution, for subsequent removal of the cross-product of the vectors V and B in data processing. This provided the basic DC measurement. Other circuitry was used to aid in interpreting the DC data and to measure rapid variations in the signals detected by the antennas. The planned DC electric field range was ± 1 V/m, the planned resolution was 0.1 mV/m, and the variational electric field was measured from 4 Hz to 1024 Hz. The DC electric field was measured at 16 samples/seconds. The variational electric field was measured from 1 microvolt/m to 10 mV/m rms. The antenna pair perpendicular to the orbit plane did not deploy.<ref name="Experiment2">{{cite web \|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-02\|title=Experiment: Vector Electric Field Instrument (VEFI)\|publisher=NASA\|date=28 October 2021\|access-date=24 November 2021}} {{PD-notice}}</ref>		The Vector Electric Field Instrument (VEFI) used flight-proven double-probe techniques with {{cvt\|20\|m}} baselines to obtain measurements of DC electric fields. This electric field investigation had the following objectives: (1) to obtain accurate and comprehensive triaxial DC electric field measurements at ionospheric altitudes in order to refine the basic spatial patterns, define the large-scale time history of these patterns, and study the small-scale temporal and spatial variations within the overall patterns; (2) to study the degree to which and in what region the electric field projects to the equatorial plane; (3) to obtain measurements of [[extremely low frequency]] ([[Extremely low frequency\|ELF]]) and lower frequency irregularity structures; and (4) to perform numerous correlative studies. The instrument consisted of six cylindrical elements {{cvt\|11\|m}} long and {{cvt\|2.8\|cm}} in diameter. Each antenna was insulated from the plasma except for the outer {{cvt\|2\|m}}. The baseline, or distance between the midpoints of these {{cvt\|2\|m}} active elements, was 20 m. The antennas were interlocked along the edges to prevent oscillation and to increase their rigidity against drag forces. The basic electronic system was very similar in concept to those used on [[Explorer 50]] (IMP-J) and [[ISEE-1]], but modified for a three-axis measurement on a nonspinning spacecraft. At the core of the system were the high-impedance (1.E12 [[ohm]]) preamplifiers, whose outputs were accurately subtracted and digitized (14-bit A/D conversion for sensitivity to about 0.1 microvolt/m) to maintain high resolution, for subsequent removal of the cross-product of the vectors V and B in data processing. This provided the basic DC measurement. Other circuitry was used to aid in interpreting the DC data and to measure rapid variations in the signals detected by the antennas. The planned DC electric field range was ± 1 V/m, the planned resolution was 0.1 mV/m, and the variational electric field was measured from 4 Hz to 1024 Hz. The DC electric field was measured at 16 samples/seconds. The variational electric field was measured from 1 microvolt/m to 10 mV/m rms. The antenna pair perpendicular to the orbit plane did not deploy.<ref name="Experiment2">{{cite web \|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1981-070B-02\|title=Experiment: Vector Electric Field Instrument (VEFI)\|publisher=NASA\|date=28 October 2021\|access-date=24 November 2021}} {{PD-notice}}</ref>

	=== Wind and Temperature Spectrometer (WATS) ===		=== Wind and Temperature Spectrometer (WATS) ===