Minimize ISEE

ISEE (International Sun-Earth Explorer) Program

ISEE is a NASA/ESA cooperative program consisting of three satellites intended to study the dynamic properties of Earth's magnetosphere and the solar wind in front of the magnetosphere (study the interaction of the interplanetary medium with the earth's immediate environment and to study the magnetosphere bow shock and magnetosheath in order to derive a better model of the interaction). Specific objectives of the mission were: 1) 2) 3) 4)

• to investigate the solar-terrestrial relationships at the outermost boundaries of the Earth's magnetosphere

• 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

• to investigate motions of and mechanisms operating in the plasma sheets

• to continue the investigation of cosmic rays and solar flare emissions in the interplanetary region near 1 AU.

The ISEE-1 and ISEE-3 spacecraft were the principal contributions of NASA, while ISEE-2 was built and managed by ESA. More than 100 investigators, representing most of the magnetospheric community, from 33 institutes were involved in the ISEE mission and its 32 instruments.

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 (interplanetary Monitoring Platform) spacecraft.


Figure 1: ISEE mission poster (image credit: UCLA) 5)


ISEE-1 and -2 Mission

The overall objectives were the observation of the near-Earth magnetosphere and its boundaries, better understanding of many phenomena, such as the Earth's bow shock, the magnetosheath and magnetopause, interactions between the tail and aurorae, and particle populations and flows in the tail.


ISEE-1 spacecraft:

ISEE-1 and ISEE-3 spacecraft are based on the IMP design pattern and were built by NASA as their main contribution to the IMS. The ISEE-1 spacecraft was spin-stabilized, had a mass of 340 kg (minisatellite) and a nominal power of 175 W. 6) 7) 8) 9)

The ISEE-1 mission has also the designations of ISEE-A and Explorer 56.


Figure 2: Artist's view of the ISEE-1 spacecraft in orbit (image credit: NASA)


Figure 3: Line drawing of the ISEE-1 spacecraft configuration (image credit: NASA)


ISEE-2 spacecraft:

The Explorer-class daughter spacecraft, ISEE-2, was part of the mother/daughter/heliocentric mission (ISEE-1, ISEE-2, ISEE-3). The mother/daughter portion of the mission consisted of two spacecraft (ISEE-1 and ISEE-2) with station-keeping capability in the same highly eccentric geocentric orbit.

The ISEE-2 minisatellite featured a spin-stabilized cylindrical bus with three deployed instrument booms. Strict measures were followed to eliminate interference from the spacecraft to some of the experiments: the entire exterior was made conductive to reduce potential difference to 1 V, the use of non-magnetic materials restricted ISEE’s DC field to < 0.25 gamma at the magnetometer, and stringent limits were imposed on the electromagnetic radiation emitted by ISEE’s interior. 10)

Attitude/orbit control: 20 rpm spin-stabilized about longitudinal axis, perpendicular to ecliptic plane; 4 spin nozzles, 2 precession nozzles, also used for separation maneuvers from ISEE-1. Cold gas propellant: 10.7 kg, Freon-14. The attitude was determined by two Earth albedo and solar aspect sensors.

The EPS (Electric Power Subsystem) used silicon cells on cylindrical panels providing a power of > 100 W (65 W after 10 years); 27 W were required by the science payload. The EPS was supported by a NiCd battery which failed after 2 years (as predicted).


Figure 4: Photo of the ISEE-2 spacecraft in the dynamic rest chamber at ESTEC (image credit: ESA)

The ISEE-2 S/C was built by Dornier-System GmbH (prime contractor), heading the STAR consortium. The ISEE-2 spacecraft had launch mass mass of 166 kg (27.7 kg science payload) with a design life of 3 years.

RF communications: S-band data was returned at data rates of 8192 bit/s (high) or 2048 bit/s (low). The spacecraft was controlled from NASA/GSFC (Goddard Space Flight Center).


Figure 5: Mating of ESA's ISEE-2 (top) with NASA’s ISEE-1 S/C at Cape Canaveral (image credit: ESA, NASA)


Launch: ISEE-1 and ISEE-2 were launched in tandem (Delta-2914 launch vehicle, joint launch provided by NASA) on October 22, 1977 from Cape Canaveral into highly elliptical geocentric orbits. The satellites passed through the magnetosphere and into the magnetosheath during each orbit providing good coverage of all the magnetosphere features over the period of a year.

Orbit: HEO (Highly Elliptical Orbit) with an apogee of 23 RE (137,806 km) and a perigee of 1.04 RE (6,600 km), inclination = 28.76º. Both spacecraft penetrated into the interplanetary medium for up to 3/4 of an orbital period depending upon the time of year.

ISEE-1 and ISEE-2 were in almost coincident orbits around the Earth with periods of approximately 57 hours (3441 minutes), and their time separation in this orbit could be altered by maneuvering ISEE-2. These two spacecraft, separated by a variable distance (50 -5000 km) and with similar instrument complements, were able to break the space-time ambiguity inevitably associated with measurements by a single spacecraft on thin boundaries which may be in motion, such as the bow shock and the magnetopause. 11)


Status of the missions ISEE-1 and ISEE-2:

• Both spacecraft reentered the Earth's atmosphere on September 26, 1987 - completing 1517 orbits of the Earth (nearly 10 years of operational life was provided).

• ISEE-1 operated in a somewhat degraded mode due to the loss of one experiment and partial loss of four others of the total complement of 13 experiments. The battery failed due to normal wear-out after 4 1/2 years of service; however, this did not curtail operations due to the spacecraft being in a full-sunlight orbit.

• ISEE-2: No units failed, apart from the expected loss of its battery.

• Following the re-entry of ISEE-1 and -2 in 1987, a special effort was undertaken to archive at the NSSDC high-quality, high time resolution data about particles, fields and waves for specific time periods deemed to be of interest to the scientific community. For ISEE-1, these special archival periods are:

1) the early years of the mission (Aug. 12, 1978 - Feb. 17, 1980) 12)

2) the period when ISEE-3 was in Earth's magnetotail (Oct. 15, 1982 - Dec. 25, 1983)

3) the "PROMIS" campaign period (March 29, 1986 - June 16, 1986).


Sensor complement of ISEE-1 and ISEE-2:

A special issue on instrumentation for the International Sun-Earth Explorer Spacecraft was provided in IEEE Transactions on Geoscience Electronics, Vol. GE-16, July 1978.


ANM/AND (Electrons & Protons)

PI: K. A. Anderson, UCB, the instrument is flown on ISEE-1 and -2. Objectives: Study of the varies energetic particle phenomena found in the Earth's magnetosphere, magnetopause, magnetosheath, bow shock, and upstream medium. Measurement over a wide range of energies, from ~1.5 to 300 keV for both electrons and protons.

The instrument was developed at UCB and consists of a pair of surface barrier semiconductor detector telescopes (one with a foil and one without a foil) and four fixed energy electric field particle analyzers. The analyzers are used to measure electrons and protons separately at 2 and 6 thousand electron volts.


LEPEDEA (Low-Energy Proton and Electron Differential Energy Analyzer):

PI: Louis A. Frank, University of Iowa. The instrument is also known by the designation FRM/FRD and is flown on ISEE-1 and ISEE-2. Objective: study of directional intensities of positive ions and electrons over a large solid angle. Energy range: 1 eV≤ E/Q ≤ 50 keV in 63 bands with 17% resolution. 13)

The instrument is a quadrispherical low-energy proton and electron differential energy analyzer (LEPEDEA), employing seven continuous channel electron multipliers in each of its two (one for protons and one for electrons). All but 2% of the 4π sr solid angle was covered for particle velocity vectors. A GM tube was also included, with a conical field of view of 40° full-angle, perpendicular to the spin axis. This detector was sensitive to electrons with E > 45 keV, and to protons with E > 600 keV. Instrument mass = 5 kg, power = 5 W.


RUM/RUD (Fluxgate Magnetometer Experiment):

PI: C. T. Russell, UCLA. The RUM/RUD fluxgate magnetometers were flown on ISEE-1 and ISEE-2. The overall objective was to obtain a quantitative understanding of the dynamic plasma and field environment of the Earth. 14)

Three NOL (Naval Ordnance Laboratory) ring core sensors in anorthogonal triad are enclosed in a flipper mechanism at the end of the magnetometer boom, 3 m from the skin of the spacecraft on ISEE l, and 2 m on ISEE 2. The flipper mechanism is actuated by heating a bimetallic strip which rotates the sensor from one stable spring-held position through 90º to a second position. During a "flip left" operation sensor which is initially anti parallel to the spin axis in the flip position, is rotated into the spin plane to look in the direction opposite spacecraft rotation. Sensor 3 is rotated from the spin plane looking in the direction of spacecraft rotation to a direction anti parallel to the spacecraft spin axis. A flip takes about 4 min at room temperature in vacuum, and requires about 5 W.

Mass of sensor assembly, electronics

0.53 kg, 1.90 kg


3.9 W (normal operations)
7.8 W (during flip operations)

Instrument size

21 cm x 12 cm x 15 cm (electronics)
11 cm x 9 cm (diameter) of sensors

Table 1: Instrument characteristics


Figure 6: RUM/RUD sensor configuration (image credit: UCLA)

Both the ISEE l and 2 magnetometers were turned on a few hours after launch and have operated continuously since that time except for brief periods during interference testing. The only operational anomalies have been a couple of status changes of the ISEE 2 instrument which were not commanded from the ground. These both occurred during the first two weeks and have not reoccurred. The flippers have been exercised every five days on both spacecraft for a total of over 50 flips to date with no evidence of aging. 15)

The instrument has two commandable ranges of ±256 γ and±8192 γ with an accuracy of 0.025%.


FPE (Fast Plasma Experiment):

PIs: S. J. Bame, Los Alamos Scientific Lab, G. Paschmann, MPI Garching. Identical fast plasma experiment (FPE) systems were placed on the ISEE-1 and ISEE-2 spacecraft. Three electrostatic analyzers (with 90º spherical section) provide electron and proton measurements. Each instrument uses a divided secondary emitter system to intercept the analyzed particles. ISEE-1 carries also a solar wind experiment (SWE) to measure solar wind ions with high resolution. The SWE is composed of two 150Â spherical section analyzers using the same set of plates. The two acceptance fans are tilted with respect to each other so that 3D characteristics of the ion distributions can be derived. 16)


WIM/KED (Medium Energy Particles Experiment):

PI: D. J. Williams, JHU/APL, Laurel, MD. Objective: Study and identify the physical mechanisms of medium energy particles associated with acceleration, source and loss processes, and boundary and interface phenomena throughout the orbits of ISEE-1 and -2.The instrument has also the designation MEPE (Medium Energy Particles Experiment) 17)

The experiment consists of the WIM instrument (Wide Angle Particle Spectrometer and a Heavy Ion Telescope) on ISEE-1 and the KED instrument (five sensor systems mounted at various angular positions with respect to the S/C spin axis) on ISEE-2.

- Protons: 20 keV - 2 MeV in 8 channels, in 16 channels on ISEE-1

- Electrons: 20 keV - 1.2 MeV in 8 channels, in 16 channels on ISEE-1

- Protons: 20 keV - 2 MeV in 12 channels on ISEE-2

- Electrons: 20 keV - 300 keV (to 1.2 MeV for 90º unit) on ISEE-2


GUM/GUD (Plasma Wave Investigation):

PI: D. A. Gurnett, University of Iowa. GUM/GUD is flown on ISEE-1 and ISEE-2. Objective: Study of wave/particle interaction in the Earth's magnetosphere and in the solar wind. The instrument on ISEE-1 uses three electric dipole antennas with lengths of 215 m, 73.5 m, and 0.6 m for the electric field measurements, and a triaxial search coil antenna for magnetic field measurements.

The ISEE-2 instrument uses two electric dipoles with lengths of 30 m and 0.6 m, and a single-axis search coil antenna for magnetic field measurements. The ISEE-2 plasma wave instrumentation consists of a 16 channel spectrum analyzer covering the frequency range from 5.62 Hz to 31.1 kHz and a wide-band waveform receiver with the capability of making waveform measurements in selected frequency ranges up to 2.0 MHz. 18) 19)

Magnetic field levels

10 - 100 kHz (3 axis, 16 channels)

Electric field levels

10 Hz - 10 kHz (3 axis, 12 channels)

Sweep frequency spectrum

10 kHz - 200 kHz (128 steps), analysis of the electric field signals

Table 2: GUM/GUD parameters


HEM (VLF Wave Propagation Experiment)

PI: R. A. Helliwell, Stanford University; the instrument is flown on ISEE-1. Objective: Study of VLF-wave-particle interactions in the magnetosphere (note: VLF = Very Low Frequency in the 10 - 30 kHz range). A second goal is the determination of the effects upon energetic particles in the magnetosphere of electrical power transmission line radiation. 20)

The instrument setup consists of three separate elements:

- a broadband VLF receiver on ISEE-1

- a broadband VLF transmitter located at Siple station in the Antarctic

- ground stations in the Antarctic and Canada

During the IMS (International Magnetospheric Study), the ISEE-1 spacecraft has been an important component of the VLF wave-injection experiments for studying interactions between coherent VLF waves and energetic particles. The coherent waves are injected into the magnetosphere by ground-based transmitters such as the Siple Station, Antarctica, and those of the Omega navigation network.


EGD (Solar Wind Ion Experiment):

PIs: E. Egidi, G. Moreno, CNR Frascati, Italy; the instrument is flown on ISEE-2, it has also the designation of SWE (Solar Wind Ion Experiment). Objective: Study of the transient phenomena in the solar wind to obtain a spatial gradients of the interplanetary plasma. The instrument measures the flow directions and energy spectra of the positive ions in the solar wind. Two modes of operation are provided, one concentrates on high angular resolution and the other on high energy resolution. The main region of interest for this instrument is outward from and including the magnetopause.

The instrument is based on two identical hemispherical electrostatic energy selectors for the measurement of positive ions in two different energy windows.

- Ions: 50eV/q - 25 keV/q

- Electrons: 35 eV - 7 keV


HPM (DC Electric Field Experiment):

PI: J. P. Heppner, GSFC; the instrument is flown on ISEE-1. Objective: Study of the transfer mechanisms (mass, momentum, and energy at the magnetopause), in particular the spatial extent and variability of the zone of strong electric fields, or fast convection in adjacent magnetospheric regions.
Instrument: 8 channel spectrum analyzer. Measurement ranges: 0.1 Hz - 3200 Hz in 9 steps.

The double probe, floating potential instrumentation on ISEE-1 is producing reliable direct measurements of the ambient DC electric field at the bow shock, at the magnetopause, and throughout the magnetosheath, tail plasma sheet and plasmasphere. In the solar wind and in middle latitude regions of the magnetosphere spacecraft sheath fields obscure the ambient field under low plasma flux conditions such that valid measurements are confined to periods of moderately intense flux. Initial results show: 21)

• a) that the DC electric field is enhanced by roughly a factor of two in a narrow region at the front, increasing B, edge of the bow shock

• b) that scale lengths for large changes in E at the sub-solar magnetopause are considerably shorter than scale lengths associated with the magnetic structure of the magnetopause

• c) that the transverse distribution of B-aligned E-fields between the outer magnetosphere and ionospheric levels must be highly complex to account for the random turbulent appearance of the magnetospheric fields and the lack of corresponding time-space variations at ionospheric levels.


HOM (Low Energy Cosmic Ray Experiment):

PI: Dieter K. Hovestadt, MPI Garching, Germany. The instrument is flown on ISEE-1 and ISEE-3. Objective: Measurement of elemental abundances, charge state composition, energy spectra, and angular distributions of energetic ions in the energy range of 2 keV/charge to 80 MeV/nucleon, and of electrons between 75 - 1300 keV. The instrument consists of three sensor systems: 22)

- ULECA is an electrostatic deflection analyzer, its energy range from about 3 to 560 keV/charge

- ULEWAT is a double dE/dX versus E thin-window flow-through proportional counter/solid-state detector telescope covering the energy range from 0.2 to 80 MeV/nucleon (Fe).

- the ULEZEQ sensor consists of a combination of an electrostatic deflection analyzer and a thin-window proportional counter. The energy range is 0.4 MeV/nucleon to 6 MeV/nucleon. Objective: collection of composition data in the trapped radiation zone.


MOM (Quasi-Static Electric Field Experiment):

PI: F. S. Mozer, UCB. The instrument is flown on ISEE-1. Objectives: 23)

- study of the quasi-static electric field over a dynamic range of 0.1 - 200mV/m

- study of wave electric fields at frequencies <1000 Hz with a sensitivity < 1 µV/m (Hz)1/2 at all frequencies

- study of plasma density and temperature

Measurements are made of the potential difference between a pair of 8 cm diameter vitereous carbon spheres which are mounted on the ends of wire booms and are separated by 73.5 m in the spin plane of the satellite.


OGM (Fast Electron Spectrometer Experiment):

PI: K. W. Ogilvie, GSFC. The instrument is flown on ISEE-1. Objective: Study of three-dimensional plasma distribution in the solar wind, magnetosheath, outer magnetosphere, and near tail regions. Instrument provides three energy ranges: 7.5-512 eV, 11-2062 eV, and 109-7285 eV. Two channel electron multipliers are used at the output of each of six cylindrical electrostatic analyzers. The total mass of two sensors and a data processing unit is 4.9 kg and the power consumption is 3.5 W. Two hundred information bits/s telemetry rate is required. 24) 25)


SHM (Ion Composition Experiment):

PI: R. D. Sharp, Lockheed, Palo Alto, CA. The instrument is flown on ISEE-1. Objective: Study of the composition of the hot magnetospheric plasma. Ion composition of the ring current, the plasma sheet, the plasmasphere, the magnetosheath, and the solar wind in order to establish the origin of the plasmas in the various regimes of the magnetosphere and to identify mass and charge dependent acceleration, transport, and loss processes. 26)

The instrument consists of two ion mass spectrometers which can be operated independently. The spectrometers point 5º above and 5º below the ISEE¿1 spin plane. Measurement ranges: 1 AMU to > 150 AMU in 64 channels at each of 32 energy channels covering the energy per charge range from 0 to ~17 keV/e.


ISEE-3 / ICE (International Cometary Explorer) mission

The ISEE-3 spacecraft had two 3 m booms for the magnetometer and plasma wave sensors, and four 49 m wire antennas for radio and plasma wave studies. The drum-shaped spacecraft was spin-stabilized with a nominal spin rate of 20 rpm. A pair of sun sensors provided an attitude knowledge of ~0.1º. A hydrazine propulsion system was used for attitude and ΔV maneuvers. There are 12 thrusters, four radial, four spin-change, two upper-axial, and two lower-axial. Eight conospherical tanks held 89 kg of hydrazine at launch, providing a total ΔV capacity of about 430 m/s. Since a libration-point mission had never been flown before, this large capacity provided a margin in case the actual station-keeping costs were higher than theoretical models predicted. 27) 28) 29) 30)

Spacecraft size: 1.77 m diameter, height = 1.58 m. The launch mass of the ISEE-3 spacecraft was 479 kg (including 89 kg of hydrazine), and power of 173 W.

Alternate designations of the ISEE-3 mission were: ISEE-C, ICE (International Cometary Explorer), and Explorer 59.

RF communications: Communications are provided in S-band.


Figure 7: Artist's view of the ISEE-3 spacecraft in orbit (image credit: NASA)


Figure 8: Photo of the ISEE-3 spacecraft during test and integration at GSFC (image credit: NASA)


Figure 9: The ISEE-3 spacecraft in flight configuration (image credit: JHU/APL)


Launch: ISEE-3 was launched on August 12, 1978 from Cape Canaveral and subsequently inserted into a "halo orbit" about the the libration point situated about 240 earth radii (Re) upstream between the Earth and the Sun.

Orbit: ISEE-3 was first placed into a halo orbit around the Lagrangian Point L1, located ~ 1.5 million km (~240 Earth radii, Re) sunward from the Earth. At L1 the spacecraft co-rotated with the Earth around the sun during the course of each year.

ISEE-3 used the tight control technique in an attempt to maintain its trajectory as close to a nominal halo orbit as possible. This mission, being the first to orbit a Sun-Earth libration point, had the luxury of a large supply of fuel to allow for uncertainties in the insertion to and maintenance of the new orbit. The relatively small errors encountered during insertion into the halo orbit left a large amount of fuel that could be used specifically for stationkeeping. Over the four years that ISEE-3 was established at the L1 point, 15 SK (Station Keeping) maneuvers were performed totaling 30.06 m/s at an average of 2.00 m/s per maneuver. The time between the maneuvers averaged 82 days.

The Earth-Moon-Sun system was used as a catapult to maneuver the spacecraft into its various mission phases (Figures 11 and 12).


Figure 10: Isometric view of the ISEE-3 halo orbit around the Sun-Earth L1 point (image credit: JHU/APL, Ref. 29)


ISEE-3 / ICE mission chronology and status:

• The original mission of ISEE-3: ISEE-3 was the first artificial object placed in a halo orbit about the Sun-Earth L1 point, proving that such a suspension between gravitational fields was possible. - Plasma passing this point arrives at the Earth approximately 1 h later where it may cause changes which can be observed by instruments on ISEE-1 and ISEE-2 (Ref. 29).

• In June 1982, after completing its original mission, ISEE-3 began the magnetotail and comet encounter phases of its mission. At this time, the spacecraft was renamed to ICE (International Cometary Explorer) for its 2.d mission period.

- 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.

- 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.


Figure 11: ISEE-3 spacecraft trajectory overview from halo orbit to geomagnetic tail

• The primary scientific objective of the ICE (International Cometary Explorer) mission 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. The represented the first ever comet encounter by a spacecraft. 31) 32)

• ICE 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.

• 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 0.1º. This will bring it back to the vicinity of the Earth-Moon system in August 2014.

• An extended ICE mission was approved by NASA in 1991 for the continued investigation of coronal mass ejections, continued cosmic ray studies, and coordinated observations with Ulysses.

• On May 5, 1997, NASA ended the ICE mission, and commanded a deactivation of the probe, with only a carrier signal left operating.

• In 1999, NASA made a brief contact to verify its carrier signal.

• On Sept. 18, 2008, NASA successfully located and reactivated ICE using the Deep Space Network. A status check revealed that all but one of its 13 experiments were still functioning, and it still has enough propellant for 150 m/s of ΔV. NASA scientists are considering reusing the probe to observe additional comets in 2017 or 2018. 33)

The ISEE-3 mission proved the utility of an orbit about the Sun-Earth L1 point for space physics (especially upstream solar wind) measurements. Orbits about the Sun-Earth L2 point could be used to measure the geomagnetic tail, but already ISEE-3 showed that double-lunar swingby orbits were better for that purpose. However, in the late 1980’s, many mission planners learned the value of orbits near the Sun-Earth L2 point for astronomical observations. A satellite there would have an unobstructed view of well over half of the sky with no interference from either the Sun, the Earth, or the Moon, all of which would remain within about 15º of the direction to the Sun. Especially observations in the infrared would benefit since the geometry and construction of the spacecraft would allow passive cooling to very low temperatures; the solar cell panels pointing towards the Sun could shade the scientific instruments. A small-amplitude Lissajous orbit about L2 would be better than the large-amplitude one that would be required by a periodic halo orbit (Ref. 29).

• NASA scientists, including a team lead by Robert Farquhar, are considering several options for the future of ICE, including redirecting it towards additional comet encounters in 2017 or 2018. Still other missions are possible for this robust, reused spacecraft before it once again drifts back into interplanetary space and subsequently returns to the vicinity of the Earth sometime in the 2040s (Ref. 30).


Figure 12: Artist's view of the various trajectory phases of the ISEE-3 (yellow, red) and ICE missions (green, blue), image credit: NASA 34)


Sensor complement of ISEE-3:

The ISEE-3 payload consisted of 13 instruments provided by both US and European groups.

ANH (X-Rays and Electrons Instrument):

PI: K. A. Anderson, UCB (University of California, Berkeley). This instrument represented the first successful flight of a high purity germanium detector on a satellite. It provided an order of magnitude improvement in the measurement of spectral properties of gamma-ray bursts than any previously flown detector. 35)

- Measurement of solar flare X-ray bursts and transient cosmic gamma-ray bursts. A proportional counter and scintillation detector cover the energy range from 5 - 228 keV.

- Measurement of electrons from ~2 keV to ~1MeV with high energy and angular resolution. (Study of interplanetary and solar electrons in the energy range between the solar wind and galactic cosmic rays).

BAH (Solar Wind Plasma Experiment):

PI: S. J. Bame, Los Alamos Scientific Lab. Two electrostatic analyzers ( with 135º spherical section) provide electron and ion measurements. Each instrument uses a divided secondary emitter system to intercept the analyzed particles.

HKH (High Energy Cosmic Ray Experiment):

PI: H. H. Heckman, UCB. Multidetector cosmic ray experiment to identify the charge and mass of incident cosmic ray nuclei from H through Fe species (over energy ranges from 20 to 500 MeV/nucleon).

HOH (Low Energy Cosmic Ray Experiment):

PI: D. Hovestadt, MPI Garching, Germany. Objective: Study of nuclear and ionic composition of solar, interplanetary, and magnetospheric accelerated and trapped particles. Measurement of elemental abundances, charge state composition, energy spectra, and angular distributions of energetic ions in the energy range of 2 keV/charge to 80 MeV/nucleon, and of electrons between 75 - 1300 keV.

DFH (Low Energy Proton Experiment):

PI: R. J. Hynds, Imperial College, London. Objective: Study of low energy protons from a solar flare to relate particle fluxes measured near the Earth to fluxes in the upper corona (investigation of the gross scale of coronal control). DFH experiment to measure low energy protons in the energy range from 35-1600 keV. The instrument was designed and built by Imperial College, the Space Science Department of ESA and the Space Research Institute of Utrecht. 36) 37) 38)

Note: The DFH is also known under the designation of EPAS (Energetic Particle Anisotropy Spectrometer). EPAS consists of a system of three identical semi-conductor particle telescopes mounted on the body of the spacecraft and inclined at 30º (Telescope 1), 60º (Telescope 2) and 135º (Telescope 3) to the spacecraft spin axis which is maintained perpendicular to the ecliptic plane (to within 1º). The spacecraft spin period is 3.04 s. Each telescope has a conical field of view of 16º semi-cone angle and a geometrical factor of 0.05 cm2 sr. 39)

The telescopes detect ions (electrons being excluded by "broom" magnets) and measure their total kinetic energy (but not their mass) by each using a stack of two silicon surface barrier detectors. The front detector (A) is 33 µm thick while the second (B) is 150 µm thick. Particle counts are defined by anticoincidence (A not B), i.e. the ions deposit all their energy in the A detector and do not intercept and trigger the B detector. The amplitude of the signal produced in the A detector is dependent on the energy deposited in the silicon, and hence on the incident ion energy. This signal is fed to pulse height discriminators which define 8 primary energy channels, E1 to E8.

In addition, a further channel, E0, monitors the instrument thermal noise but can register ions above the background if the ion flux is sufficiently high. No background noise counting-rate correction is required in any of the primary energy channels, i.e. the counts recorded are actual particle counts. The channel energy ranges depend slightly on ion mass. This is due principally to mass-dependent energy losses when the ions pass through a thin gold electrode on the front surface of the A detector.


Figure 13: The Low Energy Particle Telescope System on ISEE-3 (image credit: Imperial College, London)

MEH (Cosmic Ray Electrons and Nuclei):

PI: P. Meyer, University of Chicago). Objective: Study of the long and short-term variability of cosmic ray electrons and nuclei. Measurement of the energy spectrum of cosmic electrons in the range of 5-400 MeV. In addition, determination of the energy spectra and relative abundances of nuclei from protons in the iron group (energies from 30 MeV/n to 15 GeV/n). 40)

OGH (Plasma Composition Experiment):

PI: Keith W. Ogilvie, NASA/GSFC. Objective: Study of the dynamics and energetics of the solar wind acceleration region. Ion mass spectrometer for the measurement of ionic composition of the solar wind.

SCH (Plasma Wave Instrument):

PI: F. L. Scarf, TRW, Los Angeles. Objective: Study of interplanetary wave-particle interactions in the spectral range from 1 Hz to 100 kHz. Measurements of magnetic field and electric field components on long booms (90 m tip to tip). Magnetic field levels: 8 channels, 60 dB range, 20 Hz - 1 kHz. Electric field levels: 16 channels, 80 dB range, 20 Hz - 100 kHz.

SBH (Radio Mapping Experiment):

PI: J. L. Steinberg, Meudon Observatory, Paris. Objectives: a) monitoring the solar wind flow and perturbations of the magnetic field in conjunction with simultaneous measurements on ISEE-1 and -2 (bow shock, magnetopause, neutral sheet), and b) propagation studies of particle fluxes and shock waves in the solar wind (large scale structure of the magnetic field).
Measurement of the interplanetary scintillation of natural radio sources using two dipole antennas, one in the spin plane (90 m tip to tip) and one along the spin axis (15 m tip-to-tip). Each of these antennas drives two radiometers (10 kHz bandwidth and 3 kHz bandwidth).

SMH (Helium Vector Magnetometer):

PI: E. J. Smith, JPL. Objective: Continuous observation of the interplanetary magnetic field near 1 AU (structure, direction, polarity north-south component, magnitude, dynamic phenomena). Boom-mounted magnetometer sensor (3 m) with the following characteristics: 41)

- 8 dynamic ranges of: ±4, ±14, ±42, ±144, ±640, ±4000, ±22000, ±140000 γ

- frequency response: 0 - 3 Hz within three bands (0.1 - 1, 1 - 3, and 3 - 10 Hz) to measure fluctuations parallel to the S/C spin axis.

STH (Heavy Isotope Spectrometer Telescope, HIST):

PI: E. C. Stone, CIT (California Institute of Technology). Objective: measurement of the isotopic composition and energy of solar, galactic, and interplanetary cosmic ray nuclei for the elements Li through Ni in the energy range from ~5 to 250 MeV/nucleon. Charge, isotope, and energy range: Z 3 - 28 (Li to Ni); A 6 - 64 (6Li to 64Ni). Mass resolution: Li 0.065 - 0.83 proton masses; Fe 0.18 - -0.22 proton masses. 42) 43)

The HIST instrument consists of a telescope of solid-state detectors and associated signal-processing electronics. The telescope consists of 11 silicon solid-state detectors of graduated thicknesses. The front two detectors (M1 and M2) are two-dimensional position-sensitive detectors which measure the trajectories of individual particles entering the telescope. Use of this trajectory information results in a significant improvement in the mass resolution as compared with telescopes with similar opening angles that do not have trajectory-measuring capability.


Figure 14: Photo of the solar isotope spectrometer (image credit: NASA/JPL)

TYH (Medium Energy Cosmic Ray Experiment):

PI: Tycho T. von Rosenvinge, NASA/GSFC. Objective: measurement of the charge composition of nuclear energetic particles over the energy ranges from ~1 - 500 MeV/ nucleon, and charges from Z=1 to Z=28.

The experiment consists of two telescopes. The combined charge, mass, and energy intervals covered by these two telescopes are as follows: 44)

- Nuclei charge of energy spectra: Z = 1-30, energy range 1-500 MeV/nucleon

- Isotopes: Z=1, ΔM=1, from 4-70 MeV/n; Z=2, ΔM=1 from 1-70 MeV/n; Z=3-7, ΔM=1 from 30-140 MeV/n

- Electrons: ~2-10 MeV

- Anisotropies: Z=1-26 (1-150 MeV/n for Z=1,2); Electrons: 2-10 MeV.



3) K. W. Ogilvie, T. von Rosenvinge, A. C. Durney, “International Sun Earth Explorer - A three spacecraft program,” Science, 198, No. 4313, pp. 131-138, Oct. 1977, DOI: 10.1126/science.198.4313.131

4) K. W. Ogilvie, et al., “International Sun-Earth Explorer: A Three-Spacecraft Program,” Science, Vol. 198, No. 4313, October 14, 1977, pp. 131-138

5) “International Sun-Earth Explorer (ISEE),” UCLA, URL:


7) ISEE-1 (International Sun Earth Explorer 1), URL:

8) A. C. Durney, K. W. Ogilvie, “Introduction to the ISEE Mission (article published in the special issues: Advances in Magnetospheric Physics with GEOS-1 and ISEE - 1 and 2.),” Space Science Reviews, Volume 22, Issue 6, Dec. 1978, p. 679, DOI: 10.1007/BF00212618


10) “ISEE-2, ESA Achievements, brochure, Nov. 1, 2001, ” URL:


12) B. M. Walsh, T. A. Fritz, N. M. Lender, J. Chen, K. E. Whitaker, “Energetic particles observed by ISEE-1 and ISEE-2 in a cusp diamagnetic cavity on 29 September 1978,” Annales Geophysicae, Vol. 25, 2007, pp.2633-2640, URL:

13) “International Sun-Earth Explorer (ISEE) 1 and 2 LEPEDEA Observations,” URL:

14) C. T. Russell, “The ISEE 1 and 2 Fluxgate Magnetometers,” Transactions on Geoscience Electronics, Vol. GE-16, No 3, July 1978, also in URL:

15) X. M. Zhu, M. G. Kivelson, R. J. Walker, C. T. Russell, M. F. Thomsen, D. J. McComas, “An ISEE-1/2 spacecraft study of an unusual flux transfer event,” Advances in Space Research, Vol. 8, No 9-10, pp. (9)259-(9)262, 1988, URL:

16) S. J. Bame, J. R. Asbridge, H. E. Felthauser, J. P. Glore, G.. Paschmann, P. Hemmerich, K. Lehmann, H. Rosenbauer, “SEE-1 and ISEE-2 Fast Plasma Experiment and the ISEE-1 Solar Wind Experiment,” Transactions on Geoscience Electronics, Vol. 16, Issue 3, July 1978, pp. 216-220

17) D. J. Williams, E.. Keppler, T. A. Fritz, B. Wilken, G. Wibberenz, “The ISEE 1 and 2 Medium Energy Particles Experiment,” IEEE Transactions on Geoscience Electronics, Vol. GE-16, No 3, pp 270-280, July 1978.

18)D. A. Gurnett, F. L. Scarf, R. W. Fredricks, E. J. Smith, IEEE Transactions on Geoscience Electronics, Vol. GE-16, Issue 3, July 1978 pp.:225 - 230

19) D. A. Gurnett, R. R. Anderson, F. L. Scarf, R. W. Fredricks, E. J. Smith, “Initial results from the ISEE-1 and -2 plasma wave investigation,” Space Science Reviews, Volume 23, Number 1, March 1979, pp. 103-122

20) T. F. Bell, U. S. Inan, R. A. Helliwell, “ISEE-1 Satellite Observations of VLF Signals and associated triggered emissions from the Siple Station Transmitter,” NIPR (National Institute of Polar Research), 1980, URL:

21) J. P. Heppner, N. C. Maynard, T. L. Aggson, “Early results from ISEE-1 electric field measurements,” Space Science Reviews, Volume 22, No 6 , Dec. 1978, pp.777-789

22) D. Hovestadt, G. Gloeckler, C. Y. Fan, L. A. Fisk, F. M. Ipavich, B. Klecker, Oapos, J. J. Gallagher, M. Scholer, H. Arbinger, J. Cain, H. Hofner, E. Kunneth, P. Laeverenz, E. Tums, “The Nuclear and Ionic Charge Distribution Particle Experiments on the ISEE-1 and ISEE-C Spacecraft,” IEEE Transactions on Geoscience Electronics, Vol. 16, Issue 3, July 1978, pp. 166-175

23) F. S. Mozer, R. B. Torbert, U. V. Fahleson, C. G. Falthammar, A. Gonfalone,A. Pedersen, “Measurements of Quasi-Static and Low-Frequency Electric Fields with Spherical Double Probes on the ISEE-1 Spacecraft,” IEEE Transactions on Geoscience Electronics, Vol. 16, Issue 3, July 1978, pp. 258-261

24) K. W. Ogilvie, J. D. Scudder, H. Doong, “The Electron Spectrometer Experiment on ISEE-1,” IEEE Transaction on Geoscience Electronics, Vol. 16, Issue 3, July 1978, pp. 261-265

25) K. W. Ogilvie, J. D. Scudder, “First results from the six-axis electron spectrometer on ISEE-1,” Space Science Reviews, Vol. 23, No 1, March 1979, pp. 123-133

26) M. A. Coplan, K. W. Ogilvie, P. A. Bochsler, J. Geiss, “Ion Composition Experiment,” IEEE Transaction on Geoscience Electronics, Vol. 16, Issue 3, July 1978, pp. 185-191

27) “ISEE-3/ICE,” URL:

28) Robert W. Farquhar, “The Flight of ISEE-3/ICE: Origins, Mission History, and a Legacy,” The Journal of the Astronautical Sciences, ISSN 0021-9142, Vol. 49, No 1, January-March 2001, pp. 23-73; and previously presented at the AIAA/AAS Astrodynamics Conference, Boston, Massachusetts, August 11, 1998 (AIAA paper 98-4464).

29) David W. Dunham, Robert W. Farquhar, “Libration Point Missions, 1978 – 2002,” URL:

30) Andrew J. LePage, “The ICE mission: the first cometary encounter,” The Space Review, Sept. 20, 2010, URL:

31) Robert Farquhar, Daniel Muhonen, Leonard C. Church, “Trajectories and orbital maneuvers for the ISEE-3/ICE comet mission ,” American Institute of Aeronautics and Astronautics and American Astronautical Society, Astrodynamics Conference, Seattle, WA, Aug 20-22,1984., paper: AIAA-1984-1976


33) Emily Lakdawalla, “IT'S ALIVE,” The Planetary Society, URL:


35) K. A. Anderson, S. R. Kane, J. H. Primbsch, R. H. Weitzmann, W. D. Evans, R. W. Klebesadel, W. P. Aiello, “X-ray spectrometer experiment aboard the ISEE-C (heliocentric) spacecraft,” IEEE Transactions on Geoscience Electronics, Vol. GE-16, Issue 3, July 1978, p. 157

36) A. Balogh, R. J. Hynds, J. J. van Rooijen, G. A. Stevens, T. R. Sanderson, K. P. Wenzel, “Energetic Particles in the Heliosphere - Results from the ISEE-3 Spacecraft,” ESA Bulletin 27, 1981, pp. 4-12

37) A. Balogh, G. Van Dijen, J. Van Genechten, J. Henrion, R. Hynds, G. Korfmann, T. Iversen, J. Van Rooijen, T. Sanderson, G. Stevens, K. P. Wenzel, “The Low Energy Proton Experiment on ISEE-C,” IEEE Transactions on Geoscience Electronics, Vol. GE-16, Issue 3, July 1978, pp. 176-180

38) André Balogh, “The ISEE-3/ICE mission,” Dec. 18, 1998, URL:

39) “The ISEE-3/ICE Energetic Particle Anisotropy Spectrometer (EPAS),” URL:

40) P. Meyer, P. Evenson, “University of Chicago cosmic ray electrons and nuclei experiment on the H spacecraft,” IEEE Transactions on Geoscience Electronics, GE-16, No. 3, July 1978., pp.180-185

41) A.M.A. Frandsen, B. V. Connor, J. Van Amersfoort, E. J. Smith, “The ISEE-C Vector Helium Magnetometer,” IEEE Transactions on Geoscience Electronics, GE-16, No. 3, July 1978., pp. 195-198

42) Edward C. Stone, Richard A. Mewaldt, “Research relative to the heavy isotope spectrometer telescope experiment,” Final Report, 1 Dec. 1985 - 30 Nov. 1992, California Institute of Technology, Pasadena, Division of Physics, Mathematics, and Astronomy

43) W. E. Althouse, A. C. Cummings, T. L. Garrard, R. A. Mewaldt, E. C. Stone, R. E. Vogt, “A cosmic ray isotope spectrometer,” IEEE Transactions on Geoscience Electronics, Vol. 16, Issue 3, July 1978, p.204

44) T. T. von Rosenvinge, F. B. McDonald, J. H. Trainor, M. A. I. Van Hollebeke, I. A. Fisk, “ The Medium Energy Cosmic Ray Experiment for ISEE-C,” IEEE Transactions on Geoscience Electronics, Vol. GE-16, No. 3, July 1978, pp. 208-212

The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.