Mission Overview

The Explorer-class heliocentric spacecraft, International Sun-Earth Explorer 3, was part of the mother/daughter/heliocentric mission (ISEE 1, 2, and 3). The purposes of the mission were: (1) to investigate solar-terrestrial relationships at the outermost boundaries of the Earth's magnetosphere; (2) to examine in detail the structure of the solar wind near the Earth and the shock wave that forms the interface between the solar wind and Earth's magnetosphere; (3) to investigate motions of and mechanisms operating in the plasma sheets; and, (4) to continue the investigation of cosmic rays and solar flare emissions in the interplanetary region near 1 AU.

The three spacecraft carried a number of complementary instruments for making measurements of plasmas, energetic particles, waves, and fields. The mission thus extended the investigations of previous IMP spacecraft. The launch of three coordinated spacecraft in this mission permitted the separation of spatial and temporal effects. This heliocentric spacecraft had a spin axis normal to the ecliptic plane and a spin rate of about 20 rpm. It was initially placed into an elliptical halo orbit about the Lagrangian libration point (L1) 235 Earth radii on the sunward side of the Earth, where it continuously monitored changes in the near-Earth interplanetary medium. In conjunction with the mother and daughter spacecraft, which had eccentric geocentric orbits, this mission explored the coupling and energy transfer processes between the incident solar wind and the Earth's magnetosphere. In addition, the heliocentric ISEE 3 spacecraft also provided a near-Earth baseline for making cosmic-ray and other planetary measurements for comparison with corresponding measurements from deep-space probes. ISEE 3 was the first spacecraft to use the halo orbit.

In 1982 ISEE 3 began the magnetotail and comet encounter phases of its mission. A maneuver was conducted on June 10, 1982, to remove the spacecraft from the halo orbit around the L1 point and place it in a transfer orbit involving a series of passages between Earth and the L2 (magnetotail) Lagrangian libration point. After several passes through the Earth's magnetotail, with gravity assists from lunar flybys in March, April, September and October of 1983, a final close lunar flyby (119.4 km above the moon's surface) on December 22, 1983, ejected the spacecraft out of the Earth-Moon system and into a heliocentric orbit ahead of the Earth, on a trajectory intercepting that of Comet Giacobini-Zinner. At this time, the spacecraft was renamed International Cometary Explorer (ICE). A total of fifteen propulsive maneuvers (four of which were planned) and five lunar flybys were needed to carry out the transfer from the halo orbit to an escape trajectory from the earth-moon system into a heliocentric orbit.

The primary scientific objective of ICE was to study the interaction between the solar wind and a cometary atmosphere. As planned, the spacecraft traversed the plasma tail of Comet Giacobini-Zinner on September 11, 1985, and made in situ measurements of particles, fields, and waves. It also transited between the Sun and Comet Halley in late March 1986, when other spacecraft (Giotto, Planet-A, MS-T5, VEGA) were also in the vicinity of Comet Halley on their early March comet rendezvous missions. ICE became the first spacecraft to directly investigate two comets.

Tracking and telemetry support have been provided by the DSN (Deep Space Network) since January 1984. The ISEE-3/ICE bit rate was nominally 2048 bps during the early part of the mission, and 1024 bps during the Giacobini-Zinner comet encounter. The bit rate then successively dropped to 512 bps (on 9/12/85), 256 bps (on 5/1/87), 128 bps (on 1/24/89) and finally to 64 bps (on 12/27/91).

An update to the ICE mission was approved by NASA headquarters in 1991. It defines a Heliospheric mission for ICE consisting of investigations of coronal mass ejections in coordination with ground-based observations, continued cosmic ray studies, and special period observations such as when ICE and Ulysses are on the same solar radial line. By May 1995 ICE was being operated with only a low duty cycle, with some support being provided by the Ulysses project for data analysis. Two years later, termination of operations of ICE/ISEE3 was authorized May 5, 1997.

As of January 1990, ICE was in a 355 day heliocentric orbit with an aphelion of 1.03 AU, a perihelion of 0.93 AU and an inclination of 0.1 degree. This will bring it back to the vicinity of the earth-moon system in August, 2014.

Launch Date: 1978-08-12 at 15:12:00 UTC
Launch Vehicle: Delta
Launch Site: Cape Canaveral, United States

Trajectory Details

Type: L1 halo
Central Body: Sun
Epoch start: 1978-11-20 00:00:00 UTC
Epoch stop: 1982-06-10 00:00:00 UTC

Orbital Parameters
Periapsis 665000.0 km
Apoapsis 110000.0 km
Period 177.86000061035156 days
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Solar wind
Type: Flyby
Central Body: Moon
Closest approach time: 1983-03-30 17:47:00 UTC

Orbital Parameters
Periapsis 21307.0 km
Apoapsis
Period
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Magnetosphere
Magnetotail
Solar wind

Type: Flyby
Central Body: Moon
Closest approach time: 1983-04-23 01:03:00 UTC
Orbital Parameters

Periapsis 22875.0 km
Apoapsis
Period
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Magnetosphere
Magnetotail
Solar wind

Type: Flyby
Central Body: Moon
Closest approach time: 1983-09-27 18:00:00 UTC

Orbital Parameters
Periapsis 24527.0 km
Apoapsis
Period
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Magnetosphere
Magnetotail
Solar wind

Type: Flyby
Central Body: Moon
Closest approach time: 1983-10-21 16:32:00 UTC

Orbital Parameters
Periapsis 19178.0 km
Apoapsis
Period
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Magnetosphere
Magnetotail
Solar wind
Type: Flyby
Central Body: Moon
Closest approach time: 1983-12-22 18:44:00 UTC

Orbital Parameters
Periapsis 19178.0 km
Apoapsis
Period
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Magnetosphere
Magnetotail
Solar wind

Type: Orbiter
Central Body: Sun
Epoch start: 1983-12-22 18:44:00 UTC
Epoch stop: 1985-09-11 11:02:00 UTC

Orbital Parameters
Periapsis 0.9300000071525574 AU
Apoapsis 1.0299999713897705 AU
Period 355.0 days
Inclination 0.10000000149011612°
Eccentricity 0.05000000074505806

Regions Traversed
Magnetosphere
Magnetotail
Solar wind

Type: Flyby
Central Body: Comet P/Giacobini-Zinner
Closest approach time: 1985-09-11 11:02:00 UTC

Orbital Parameters
Periapsis 7800.0 km
Apoapsis
Period
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Tail (cometary)

Type: Orbiter
Central Body: Sun
och start: 1985-09-11 11:02:00 UTC
Epoch stop: 1985-10-31 00:00:00 UTC

Orbital Parameters
Periapsis 0.9300000071525574 AU
Apoapsis 1.0299999713897705 AU
Period 355.0 days
Inclination 0.10000000149011612°
Eccentricity 0.05000000074505806

Regions Traversed
Magnetosphere
Magnetotail
Solar wind

Type: Flyby
Central Body: Comet P/Halley
Closest approach time: 1985-10-31 00:00:00 UTC

Orbital Parameters
Periapsis 0.9300000071525574 AU
Apoapsis
Period
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Solar wind

Type: Orbiter
Central Body: Sun
Epoch start: 1985-10-31 00:00:00 UTC
Epoch stop: 1986-03-28 00:00:00 UTC

Orbital Parameters
Periapsis 0.9300000071525574 AU
Apoapsis 1.0299999713897705 AU
Period 355.0 days
Inclination 0.10000000149011612°
Eccentricity 0.05000000074505806

Regions Traversed
Magnetosphere
Magnetotail
Solar wind

Type: Flyby
Central Body: Comet P/Halley
Closest approach time: 1986-03-28 00:00:00 UTC

Orbital Parameters
Periapsis 0.20999999344348907 AU
Apoapsis
Period
Inclination 0.0°
Eccentricity 0.0

Regions Traversed
Solar wind

Type: Orbiter
Central Body: Sun
Epoch start: 1986-03-28 00:00:00 UTC

Orbital Parameters
Periapsis 0.9300000071525574 AU
Apoapsis 1.0299999713897705 AU
Period 355.0 days
Inclination 0.10000000149011612°
Eccentricity 0.05000000074505806

Regions Traversed
Magnetosphere
Magnetotail
Solar wind

Instrumentation

Solar wind plasma, 2-D and 3-D distr. fns. p: 150eV - 7keV; e: 10eV-1keV

This experiment was designed to make an integrated study of the nature, origin, and evolution of structure in the interplanetary medium. Also, the thermal state of the interplanetary plasma was studied, unperturbed by the earth's bow shock. Ion velocity distributions were measured by a 135-deg spherical electrostatic analyzer in both two and three dimensions. Step energy resolution for each energy window was 4.2%. Electron velocity distributions were measured by a 90-deg spherical electrostatic analyzer, also in two and three dimensions. The energy window per step for electrons was 10%. Channeltron electron multipliers were used as detectors for each of the analyzers. Solar wind electrons were measured in 15 contiguous channels from 8.5 to 1140 eV. A special photoelectron range of 1.6 to 220 eV could be commanded. Various mixtures of data for two-dimensional and three-dimensional distribution functions could be selected. Ions were measured in 32 channels from 237 eV per charge to 10.7 keV per charge. Various modes were available for basic sweep, search, and tracking of the peak of the distribution. The ion instrument failed to return usable data after February 26, 1980.

Vector Helium Magnetometer

The instrumentation for this experiment consisted of a boom-mounted triaxial vector helium magnetometer. Measurements were made of the steady magnetic field and its low-frequency variations. Eight field amplitude ranges (minus to plus 4, 14, 42, 144, 640, 4000, 22,000, and 140,000 nT) were available. The instrument ranged up and down automatically or could be commanded into a specific range. The field equivalent noise power spectral density was 2E-4 nT squared per Hz (independent of frequency), or 0.01 nT rms in the passband 0 to 0.5 Hz. A single-axis spectrum analyzer measured fluctuations parallel to the spacecraft spin axis in three frequency bands centered at 0.33, 3.2, and 8.8 Hz.

Low-Energy Cosmic Rays

This instrument, designated HOH, carried on ISEE 1 and ISEE 3, was designed to measure solar, interplanetary, and magnetospheric energetic ions in numerous bands within the energy range 2 keV/charge to 80 MeV/nucleon, and electrons in four contiguous bands from 75 to 1300 keV. At the lower energies, charge states of heavy ions in the high-speed (›500 km/s) solar wind were determined. In the range 0.3 to 80 MeV/nucleon, the energy spectra, anisotropies, and composition of energetic ions were determined. In the limited range 0.4 to 6 MeV/nucleon, simultaneous determination of ionic and nuclear charge was possible. The instrument consisted of three different sensor systems. ULECA (ultralow-energy charge analyzer) was an electrostatic analyzer with solid-state detectors. Its energy range was approximately 3 to 560 keV/charge. ULEWAT (ultralow-energy wide-angle telescope) was a dE/dx vs E, thin-window, flow-through proportional counter/solid-state detector telescope covering the range 0.2 to 80 MeV/nucleon (Fe). ULEZEQ (ultralow-energy Z, E, and Q) was a combination of an electrostatic analyzer and a dE/dx versus E system with a thin-window proportional counter and a position-sensitive solid-state detector. The energy range was 0.4 to 6 MeV/nucleon. Data could be obtained in 45-deg sectors.

Medium Energy Cosmic Rays, 1-500 MeV/n, Z = 1-28; Electrons: 2-10 MeV

This experiment was designed to study the composition of solar cosmic rays from hydrogen through iron and the elemental abundance of galactic cosmic rays. Three cosmic-ray telescopes, plus a proportional counter for measurement of electrons and X rays, comprised the instrumentation. Nuclei with Z between 1 and 30 were measured in various energy windows in the range 1 to 500 MeV/nucleon. Unit mass resolution was obtained for isotopes with Z equal to 1, 2, and 3 to 7 in the energy ranges 4 to 70, 1 to 70, and 30 to 140 MeV/nucleon, respectively. Electrons were measured in the energy range approximately 2 to 10 MeV. Anisotropy information was obtained for the electrons and nuclei with Z equal to 1 to 26.

High-Energy Cosmic Rays, H to Ni, 20-500 MeV/n

This experiment was designed to determine the isotopic abundance in the primary cosmic rays for hydrogen through nickel. The instrument used a 10-element solid-state particle telescope consisting of lithium-drifted silicon detectors. Energy ranges measured ran from approximately 20 to approximately 500 MeV/nucleon. The direction of incident nuclei was obtained from a six-plane drift chamber with 2-deg resolution.

Cosmic-Ray Energy Spectrum, H-Fe 30 MeV/n - 15 GeV/n, Electron: 5-400 MeV

This experiment was designed to study particle propagation within the solar system and the properties of the interplanetary medium. The experiment resolved electrons (differential spectrum from 5 to 400 MeV) and nuclei from protons to the iron group (differential spectra and relative abundances from 30 to 15,000 MeV/nucleon). A charged-particle telescope was used to make these measurements. It consisted of three solid-state detectors, a gas Cerenkov counter, a CsI scintillation detector, two plastic scintillation counters, and a quartz Cerenkov counter. The design of the telescope was based on that used in experiment 68-014A-09 for OGO 5.

Plasma Waves Spectrum Analyzer 17 Hz - 100 kHz (E); 0.3 Hz-1 kHz (B)

This experiment was designed to provide data for plasma-wave studies undertaken to gain a better understanding of the wave-particle interaction and plasma instabilities, which lead to the equivalent collision phenomena that produce apparent fluid-like behavior in the solar wind near 1 AU. Two electric dipoles and a boom-mounted magnetic search coil were used to measure magnetic and electric field wave levels from 17 Hz to 1 kHz in 8 channels and electric field levels from 17 Hz to 100 kHz in 16 channels. In addition, a third spectrum analyzer with three bands between 0.316 and 8.8 Hz was included for measurement of the magnetic field. This unit used the search coil, but was located within the electronics unit of experiment 78-079A-02.

Energetic Particle Anisotropy Spectrometer (EPAS)

This experiment, designated DFH, was designed to study low-energy solar proton acceleration and propagation processes in interplanetary space. The instrument measured the energy spectrum in 8 channels, and the 3-dimensional angular distribution of protons in the energy range 0.035 to 1.6 MeV with a basic time resolution of 16 s. Counts of each channel were grouped into eight 45-deg sectors. The instrument consisted of three identical telescopes mounted at 30, 60, and 135 deg relative to the spacecraft spin axis, each containing two surface-barrier detectors, a mechanical collimator, and a “broom” magnet to sweep away electrons.

Interplanetary and Solar Electrons 2 keV to › 1 MeV

This experiment was designed to study spectra and anisotropies of interplanetary and solar electrons (2 to 1000 keV) in the transition energy range between solar wind and low-energy cosmic rays. The electrons were measured by a pair of passively cooled, surface-barrier, semiconductor-detector telescopes (approximately 15 keV to approximately 1 MeV) and by a hemispherical plate electrostatic analyzer with channel-multiplier detectors (2-18 keV). Counting rates were sectored into angular sectors about either the magnetic field or the sun direction. The telescope yielded 8 or 16 sectors and the analyzer yielded 16 sectors.

Radio Mapping of Solar Wind Disturbances (Type III bursts) in 3-D; 30 kHz - 2 MHz

The principal purpose of this experiment is to map the trajectories of type III solar bursts by determining the angular coordinates of a localized source as a function of frequency and time. The radial distance may be obtained by triangulation with observations from another satellite, or from assumptions about the density of the interplanetary medium.

Two perpendicular dipole antennas are used. A 90 m tip-to-tip antenna in the spin plane of ISEE-3, referred to as the S antenna, sees a signal which is modulated because of the changing aspect of the source due to the spacecraft's rotation. The Z antenna is 14 m tip-to-tip, along the spin axis. From the S measurements, the azimuth and strength of the source are obtained. Comparison of S and Z observations provides the elevation of the source from the spin plane and an estimate of its angular diameter.

Measurements are made in 12 frequency channels, between 30 and 1980 kHz, in each of two bandwidths, 10 kHz (B), and 3 kHz (N). Every 1.5 seconds (which is nearly one-half spin), one measurement of Z and 11 of S are made for one frequency channel in each bandwidth, interleaving B and N observations. This provides nearly the full range of modulation possible from the S antenna. (At data rates lower than 2048 bps, proportionally fewer S samples are taken.) The frequency channel is selected according to a fixed 72 step program, designed to observe each frequency at uniform intervals but with shorter intervals for the higher frequencies. Alternate modes of observation are possible using only the B or only the N bandwidth. The 72-step sequence takes 108 seconds to complete. Self-calibration occurs every 18 hours.

Solar Wind Ion Composition, 300-600 km/s 840 eV/Q to 11.7 keV/Q; M/Q = 1.5 to 5.6

This experiment consisted of a hemispherical electrostatic energy analyzer and a Wien velocity filter configured as a mass spectrometer to determine the charge state and isotopic constitution of the solar wind. The instrument had an energy-per-unit-charge range of 0.84 to 11.7 keV per charge, a mass-per-unit-charge range of 1.5 to 5.6 u per charge, and a velocity range of 300 to 600 km/s.

Cosmic Ray Isotope Spectrometer 5-250 MeV/n; Z=3-28; A=6-64; (Li-Ni)

This experiment was designed to study the isotopic constitution of solar matter and galactic cosmic-ray sources, the processes of nucleosynthesis in the sun and in the galaxy, and astrophysical particle acceleration processes. The following species were resolved: lithium through nickel (Z from 3 through 28 and A from 6 through 64) in the energy range from 5 to 250 MeV/nucleon. The mass resolution was ‹0.3 u for Z‹30.

Ground Based Solar Studies

This experiment consisted of the measurement of large-scale solar magnetic and velocity fields with the Stanford ground-based solar telescope, and the comparison of these measurements with measurements of the interplanetary magnetic field and solar wind made by other experiments on this spacecraft. The purpose of the experiment was to study the large-scale structure of the solar magnetic field and its extension into interplanetary space by the solar wind.

X- and Gamma-Ray Bursts, 5-228 keV

This experiment was designed to provide continuous coverage of solar-flare X rays and transient cosmic gamma-ray bursts. Detectors were a xenon-filled proportional counter (5-14 keV in 6 channels) and a NaI scintillator (12-1250 keV in 12 channels). There were four operating modes: normal, flare-1, flare-2, and gamma-burst. In the normal mode, the time resolution was 0.5 to 4 s, depending on the channel. In the gamma-burst mode, the best time resolution was 0.25 to 125 ms and used stored data.

Gamma-Ray Bursts, 0.05-6.5 MeV Direction, Profile, Spectrum

This experiment was designed to recognize and record the time history of gamma-ray bursts, and to provide high-resolution spectra of gamma-ray burst photons between 0.05 and 6.5 MeV. Three detectors were used. Detector 1 was a 4-cm diameter by 3-cm-thick germanium crystal, radiatively cooled to operate at approximately 101 deg K. The energy range was between 0.12 and 6.5 MeV, and the energy resolution was ‹ 3.5 keV at 1 MeV. A 4096-channel A/D converter digitized the signals for input to the gamma-burst digital instrumentation, which was in the low-energy cosmic-ray experiment, 78-079A-03. Detector 2 consisted of the CsI and surrounding detectors in the cosmic-ray electrons and nuclei experiment, 78-079A-06. Both temporal and spectral information were obtained from this detector. This detector was felt to be somewhat noisy. Detector 3 consisted of the smaller CsI crystal in experiment 78-079A-03. Its energy range began at about 79 keV. Two time-history memories of 2000 12-bit words were used, and received information from any of the three detectors by command. The stored values were time intervals over which a fixed number (1-128) of counts was accumulated. The time-interval clock frequency was selectable from 1 to 8 kHz. Spectral information from either detector 1 or 2 was stored in a third memory of 3072 16-bit words. Twelve bits were used for pulse-height data and four bits for time. The counting rate input to the time history memories caused a trigger signal to occur if the rate exceeded a commandable value. When this occurred, all three memories were allowed to fill. These memories could be read out at a very low bit rate, either automatically or by command.

Telmetry

The data handling system gathers the scientific and engineering data from all systems in the spacecraft and formats these into a PCM serial stream for transmission. The system provides all timing and control signals required for this task. It consists of a data multiplexer unit (DMU), one or two subplexer units, and a mass storage unit. The first two items are identical to units flown on the International Ultraviolet Explorer (IUE) spacecraft, while the last, the mass storage unit, is unique to ISEE.

The DMU has two fixed and two programmable formats which can be altered by ground command. There are two DMUs on the spacecraft which can operate at variable bit rates, selectable by ground command, of 2048, 1024, 512, 256, 128, and 64 information bits per second. (The telemetry bit rate is twice the information bit rate). The subplexer is used to handle data input from the scientific or spacecraft instruments and for generating additional timing signals. It acts as a buffer to the DMU and is used when the number of inputs from the spacecraft exceeds the DMU's capacity. The mass storage unit is used for a number of scientific instruments that require rapid sampling over short intervals of time. The data are temporarily stored in the mass memory until it is telemetered. A mass memory is employed in place of individual memories in each instrument to reduce cost.

The functions of telemetry, command and ranging are handled by two identical S-band transponders. On ISEE-3 one transponder was designed to operate continuously, transmitting PCM telemetry. The second transponder is used only for ranging; however, the PCM telemetry can be switched to the second transponder in the event of failure of the first transponder. The choice of S-band over VHF for ISEE-3 was dictated primarily by stringent telemetry downlink requirements such as the long range and a view angle near the solar direction. The uplink frequencies are 2041.95 and 2090.66 MHz; the downlink frequencies are 2217.50 and 2270.40 MHz. The transmitter output power is 5 watts. Both transponder transmitters can transmit through the medium gain antenna simultaneously, although they will radiate with opposite circular polarizations. This antenna has a 9-dB gain and a vertical beam width of 18 degrees.

From initial launch, the ISEE-3 mission was supported by the Ground Spaceflight Tracking and Data Network (GSTDN) with orbit determination (OD) performed at the Goddard Space Flight Center (GSFC). At the comet encounter distance of 70 million km from earth, the spacecraft was beyond the range of the GSTDN. This necessitated the transfer of support, in early January 1984, to the Deep Space Network (DSN) which is operated by the Jet Propulsion Laboratory (JPL).

Responsibility for OD was given to the institution providing the tracking support. However, during December 1983, GSFC and JPL carried out parallel tracking and OD support. Responsibility for maneuver analysis and design, along with trajectory product generation for investigator support, remained at GSFC for the duration of the mission.

After January 6, 1984, tracking and data acquisition of ICE was limited to the DSN 64-meter subnet. However, the first year of interplanetary cruise was supported by only one antenna, DSS 63 in Spain. Beginning in mid-December 1984, occasional passes were provided by DSS 14 at Goldstone. In mid-January 1985, DSS 63 went down for modifications, leaving only DSS 14 to provide tracking support. After June 1985, both stations supported the mission through the comet encounter. The ISEE-3/ICE bit rate was nominally 2048 bps during the early part of the mission, and 1024 bps during the Giacobini-Zinner comet encounter. The bit rate then successively dropped to 512 bps (on 9/12/85), 256 bps (on 5/1/87), 128 bps (on 1/24/89) and finally to 64 bps (on 12/27/91).

Science
Summary