Spacecraft Frame Of Reference Research Articles

Kinetic and Shear Alfvén Waves in a Large Guide-field Reconnection at Earth's Magnetopause

A large guide-field (∼1.1B o) reconnection X-line, observed by the Magnetospheric Multiscale spacecraft during an outbound magnetopause crossing, is studied for Alfvén waves. Here B o is the reconnecting field magnitude. The current sheet thickness of the magnetopause was ∼2.6 ion inertial lengths (∼269 km), where field-aligned counter-streaming electrons were observed and Hall electromagnetic fields were identified. A remarkable finding was that a kinetic Alfvén wave (KAW) was seen in the magnetopause upstream region after a shear Alfvén wave (SAW) was encountered in the magnetopause layer. The presence of both the SAW and KAW near the reconnection X-line is for the first time reported. In the spacecraft frame of reference, the SAW has a dominant frequency at ∼0.74 Hz, while the KAW has two dominant frequencies at ∼0.38 and ∼0.64 Hz. The wave energy for KAW and SAW was mostly carried away from the reconnection site by the Poynting flux parallel to the magnetic field. The parallel temperatures for ions and electrons were increased at KAW. The peaks of T ∥/T ⊥ for ions were located near the wave peaks, while the ratio peaks for electrons were near the wave troughs. Our findings suggest that KAWS and SAWs can be generated by asymmetric reconnection with a large guide field.

Non-universality of the Turbulent Spectra at Sub-ion Scales in the Solar Wind: Dispersive Effects versus the Doppler Shift

Large surveys of the power spectral density of the magnetic fluctuations in the solar wind have reported different slope distributions at MHD, sub-ion and sub-electron scales: the smaller the scale, the broader the distribution. Here, we review briefly some of the most relevant explanations of the broadening of the slopes at sub-ion scales. Then, we present a new one that has been overlooked in the literature, which is based on the relative importance of the dispersive effects with respect to the Doppler shift due to the mean flow speed. We build a toy model based on a dispersion relation of a linear mode that matches at high frequency (ω ≳ ω ci) the Alfvén (respectively whistler) mode at high oblique (respectively quasi-parallel) propagation angles θ kB . Starting with a double power-law spectrum of turbulence in the inertial range and at the sub-ion scales, the transformed spectrum (in frequency f) as it would be measured in the spacecraft reference frame shows a broad range of slopes at the sub-ion scales that depend both on the angle θ kB and the flow speed V. Varying θ kB in the range 4°–106° and V in the range 400−800 km s−1 the resulting distribution of slopes at the sub-ion scales reproduces quite well the observed one in the solar wind. Fluctuations in the solar wind speed and the wavevector anisotropy of the turbulence may explain (or at least contribute to) the variability of the spectral slopes reported from spacecraft observations in the solar wind.

Determination of Plasma, Pickup Ion, and Suprathermal Particle Spectrum in the Solar Wind Frame of Reference

Abstract Particle spectra directly measured by a plasma or low-energy particle experiment on spacecraft often contain instrumental effects due to a limited field of view or angular resolution. It is because the particle distribution function at low energies is highly anisotropic in the spacecraft frame of reference, in which the measurements are made. In this paper, we present a new mathematical method of transforming the particle spectrum to the solar wind frame of reference, where the particle distribution can be assumed to be nearly isotropic. The transformed particle spectrum allows us to investigate the properties of the solar wind, pickup ions, and suprathermal particles without concern for instrumental effects. We apply the method to the measurements made by the Solar Wind Ion Composition Spectrometer on Ulysses. Our results demonstrate that the transformed spectrum can improve the determination of the solar wind density and temperature from the previously published methods. A brief survey of Ulysses data shows that suprathermal ions in the slow solar wind frequently display a velocity distribution very close to the v −5 power law.

Absence of the strahl during times of slow wind

Abstract. It is not uncommon during periods when the solar wind speed is less than 425 km s−1 to observe near 1 AU no evidence of a strahl population in either the electron solar wind or within the foreshock. Estimating the fluid flow within each energy step returned from the Plasma Electron And Current Experiment (PEACE) on board Cluster-2 often finds that in slow wind the GSE spherical flow angles in energies above where there is a clear core/halo signature are often close to radial with no evidence of a field-aligned flow. This signifies the lack of a strahl presence in the electron velocity distribution function (eVDF). When there is no obvious strahl signature in the data, the electrons above the core/halo in energy appear to be unstructured and smeared in angle. This can either be interpreted as due to statistical noise in low counting rate situations or the result of intense scattering. Regions where the strahl is seen and not seen are often separated by a very thin boundary layer. These transitions in the spacecraft frame of reference can be quite rapid, generally occurring within one to two spins (4–8 s).

A versatile retarding potential analyzer for nano-satellite platforms.

The design of the first retarding potential analyzer (RPA) built specifically for use on resource-limited cubesat platforms is described. The size, mass, and power consumption are consistent with the limitations of a nano-satellite, but the performance specifications are commensurate with those of RPAs flown on much larger platforms. The instrument is capable of measuring the ion density, temperature, and the ram component of the ion velocity in the spacecraft reference frame, while also providing estimates of the ion composition. The mechanical and electrical designs are described, as are the operating modes, command and data structure, and timing scheme. Test data obtained using an ion source inside a laboratory vacuum chamber are presented to validate the performance of the new design.

LEOrbit: A program to calculate parameters relevant to modeling Low Earth Orbit spacecraft–plasma interaction

Understanding the physics of interaction between satellites and the space environment is essential in planning and exploiting space missions. Several computer models have been developed over the years to study this interaction. In all cases, simulations are carried out in the reference frame of the spacecraft and effects such as charging, the formation of electrostatic sheaths and wakes are calculated for given conditions of the space environment. In this paper we present a program used to compute magnetic fields and a number of space plasma and space environment parameters relevant to Low Earth Orbits (LEO) spacecraft–plasma interaction modeling. Magnetic fields are obtained from the International Geophysical Reference Field (IGRF) and plasma parameters are obtained from the International Reference Ionosphere (IRI) model. All parameters are computed in the spacecraft frame of reference as a function of its six Keplerian elements. They are presented in a format that can be used directly in most spacecraft–plasma interaction models. Program summaryProgram title: LEOrbitCatalogue identifier: AENY_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENY_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 270308No. of bytes in distributed program, including test data, etc.: 2323222Distribution format: tar.gzProgramming language: FORTRAN 90.Computer: Non specific.Operating system: Non specific.RAM: 7.1 MBClassification: 19, 4.14.External routines: IRI, IGRF (included in the package).Nature of problem: Compute magnetic field components, direction of the sun, sun visibility factor and approximate plasma parameters in the reference frame of a Low Earth Orbit satellite.Solution method: Orbit integration, calls to IGRF and IRI libraries and transformation of coordinates from geocentric to spacecraft frame reference.Restrictions: Low Earth orbits, altitudes between 150 and 2000 km.Running time: Approximately two seconds to parameterize a full orbit with 1000 points.

Observation and theoretical modeling of electron scale solar wind turbulence

Abstract Turbulence at MagnetoHydroDynamics (MHD) scales in the solar wind has been studied for more than three decades, using data analysis, theoretical and numerical modeling. However, smaller scales have not been explored until very recently. Here, we review recent results on the first observation of cascade and dissipation of the solar wind turbulence at the electron scales. Thanks to the high resolution magnetic and electric field data of the Cluster spacecraft, we computed the spectra of turbulence up to ∼ 100 Hz (in the spacecraft reference frame) and found evidence of energy dissipation around the Doppler-shifted electron gyroscale f ρ e . Before its dissipation, the energy is shown to undergo two cascades: a Kolmogorov-like cascade with a scaling f − 1.6 above the proton gyroscale, and a new f − 2.3 cascade at the sub-proton and electron gyroscales. Above f ρ e the spectrum has a steeper power law ∼ f − 4.1 down to the noise level of the instrument. Solving numerically the linear Maxwell–Vlasov equations combined with recent theoretical predictions of the Gyro-Kinetic theory, we show that the present results are consistent with a scenario of a quasi-two-dimensional cascade into Kinetic Alfven modes (KAW). New analyses of other data sets, where the Cluster separation (of about ∼ 200 km ) allowed us to explore the sub-proton scales using the k-filtering technique, and to confirm the 2D nature of the turbulence at those scales.

Characterization of waves in the vicinity of an interplanetary directional discontinuity

[1] Directional discontinuities are frequently encountered in the solar wind. This study utilizes the possibility of simultaneous four-point measurements that the Cluster satellites provide for an investigation of the waves near one such interplanetary discontinuity event. In particular, the k-filtering technique has for the first time been applied for the wave characterization in terms of frequency, wave vector, wave power, and polarization at different distances from a discontinuity. The advantages of the k-filtering method are that these parameters can be transformed into the plasma frame of reference to allow comparison with theory and that it is possible to detect more than one wave mode at each frequency in the spacecraft frame of reference. The discontinuity event in this study was chosen because its wave activity had unusually high power and because it also contains signatures of large-scale magnetic reconnection, such as a reconnection exhaust. Two wave modes are found: one which has the features of a shear Alfvén wave with propagation direction ordered by the background magnetic field direction and one which behaves like a compressional Alfvén wave and is ordered by the discontinuity normal. Both wave modes become weaker farther away from the discontinuity, but the compressional Alfvén mode is more suppressed. The shear mode dominates for long wavelengths at all distances from the discontinuity. The wave field is also found to be asymmetric on the two sides of the event.

The k‐filtering technique applied to wave electric and magnetic field measurements from the Cluster satellites

The k‐filtering technique is a method to characterize stationary fluctuations in space plasmas in terms of the wave energy distribution in the frequency and wave vector space. It has the ability to distinguish between wave modes of the same frequency in the spacecraft frame of reference, but with different wave vectors. This method is based on simultaneous multi‐point measurements of the wave field components, where a filter bank is used to enhance the spatial resolution. We have for the first time combined electric field data from the Electric Field and Wave (EFW) instrument and magnetic field data from the Spatio‐Temporal Analysis of Field Fluctuation (STAFF) instrument on the four Cluster spacecraft in order to determine the wave energy distribution. The k‐filtering technique has previously been performed with only the magnetic field measurements. The reason to include the electric field measurements is that it is important to include as much data as possible in order to get the best possible estimation of the wave energy distribution. Another reason is that it also enables comparisons between the electric and the magnetic part of the wave energy distribution to make it possible to differentiate the observed waves according to their polarization. The k‐filtering method has been extended in order to allow for two measured components of the electric field, and also for the possibility that the electric field measurements from one or more satellites cannot be used for k‐filtering. The technique has been applied on satellite data from the magnetosheath and the foreshock, and from these examples it is clear that k‐filtering using both electric and magnetic field measurements is a good tool for characterizing the waves that are observed in space.

Cluster satellite observations of mHz pulsations in the dayside magnetosphere

On 17 August 2002 the Cluster spacecraft moved through the dayside magnetosphere. Between 16:00 and 18:30 UT clear monochromatic oscillations are seen in both electric field and magnetometer data. The frequency is 4.2 mHz in the spacecraft frame of reference. The oscillations have a clear spatial localisation. The magnetic field oscillations are radially polarised in the plane perpendicular to the background magnetic field, indicating that the wave is in the poloidal mode. From the difference in phase between the satellites we estimate the azimuthal wave number, m, to be about 130, consistent with the magnetic field polarisation. The frequency is stable for different L-values as well as over time. From the value of m, the Doppler shift due to satellite motion is estimated to 0.5 mHz. By looking at the phase of the electric and the magnetic field close to the equator we conclude that the oscillations are in a mode with an odd number of half wavelengths between the two ionospheres.

Bow shock specularly reflected ions in the presence of low-frequency electromagnetic waves: a case study

Abstract. An energetic ion (E≤40) event observed by the CLUSTER/CIS experiment upstream of the Earth's bow shock is studied in detail. The ion event is observed in association with quasi-monochromatic ULF MHD-like waves, which we show modulate the ion fluxes. According to three statistical bow shock position models, the Cluster spacecrafts are located at ~0.5 Re from the shock and the averaged bow shock θBn0 is about ~30°. The analysis of the three-dimensional angular distribution indicates that ions propagating roughly along the magnetic field direction are observed at the onset of the event. Later on, the angular distribution is gyrophase-bunched and the pitch-angle distribution is peaked at α0~θBn0, consistent with the specular reflection production mechanism. The analysis of the waves shows that they are left-handed in the spacecraft frame of reference (right-handed in the solar wind frame) and propagate roughly along the ambient magnetic field; we have found that they are in cyclotron-resonance with the field-aligned beam observed just upstream. Using properties of the waves and particles, we explain the observed particle flux-modulation in the context of θBn changes at the shock caused by the convected ULF waves. We have found that the high count rates coincide with particles leaving the shock when θBn angles are less than ~40°, consistent with the specular reflection hypothesis as the production mechanism of ions.

Electromagnetic wave structures within subauroral polarization streams

We report on oscillations in electric (δEY) and magnetic (δBZ) fields and plasma density (δNi) observed by Defense Meteorological Satellite Program (DMSP) satellites within fast subauroral convection streams in the evening sector during the magnetic storm of 6 November 2001. There are two types of wave phenomena. The first and more common is characterized by electromagnetic and plasma density variations that have the same frequency range of ∼0.15 Hz in the spacecraft frame of reference. The second is characterized by large‐amplitude plasma and field oscillations over a broader range of frequencies ∼0.1 to 0.3 Hz. In this case the perturbation densities and fields appear to have different frequency responses. In this and other magnetic storms, strong waves are associated with the precipitation of ∼30 keV ions. Ratios of δEY/δBZ indicate encounters with mixtures of electromagnetic (in part Alfvénic) and electrostatic modes. Poynting vectors associated with the oscillations can be directed either into or out of the ionosphere. The density perturbations appear to be extended east‐west corrugations in the plasma flow streams with north‐south wavelengths of ∼50 km. The δEY and δNi variations were anticorrelated, as required for current conservation. Our analysis shows that Alfvénic perturbations are consistent with expected effects of irregular potential distribution around ionospheric density irregularities mapped to the magnetosphere. Inertial currents act to generate mesoscale field‐aligned currents carried by Alfvén waves, as was previously discussed with regards to auroral arcs formation. We suggest that δNi irregularities observed by DMSP satellites in the evening sector began as striated plasma patches in the polar cap that convected to subauroral latitudes.

Escape from Gyrostat Trap States

Some results are presented on the dynamics of gyrostats containing two axisymmetric rotors where one of the rotors is viscously damped and the other is subject to a controllable torque. The purpose of this arrangement is to investigate the use of internal torques to enable a spacecraft to escape from a trap state. Suppose the spacecraft is intendedto operatein a stateinwhichtheprimary rotor R1 hasa specie ed angularmomentum and theotherrotor R2, subject only to internal viscous torques, is not spinning relative to the spacecraft reference frame. Normally this state is asymptotically stable because of the damping. It is possible that a different asymptotically stable state exists satisfying these conditions on the rotor momenta, in much the same way that a single-spinner may spin in either direction about its major axis. If the spacecraft becomes trapped in the alternate state, it is necessary to help it escape. In an earlier study, a pulsing procedure was proposed. Herein we show that periodic torquing of the primary rotor may lead to escape but generally is rather ineffective. An alternative escape procedure is presented that essentially is guaranteed to lead to escape. Unlike the local analysis that suggests the pulsing procedure, the procedure used here is based on a global analysis of the rotational dynamics.

Evidence for enhanced dynamic flow in ionospheric holes from the pioneer venus Orbiter Neutral Mass Spectrometer

The Pioneer Venus Orbiter Neutral Mass Spectrometer (ONMS) was operated in ion mode during the third nightside cycle of the Orbiter around Venus. Data have been acquired for the outbound ionospheric holes on orbit numbers 530 and 531. Holes are observed as deep troughs in the electron and ion density in the antisolar ionosphere of Venus, primarily between 23 and 2 hours local solar time, usually in north-south pairs and in conjunction with enhanced sunward or antisunward magnetic fields. Several models based on Orbiter data suggest that the holes are also regions of enhanced ion flow speeds. Spin modulated ion data acquired from the ONMS for species He +, C +, N + and O +, were reduced to obtain relative ion composition. The time of the maximum in the apparent ion flow observed in the spacecraft reference frame relative to that predicted by the spacecraft velocity is a measure of one component of the ion drift in the ecliptic plane. Although it is difficult to determine this component in the hole region due to the steep density gradients and low particle densities (< 10 cm −3), its minimum magnitude in the holes is of the order of 3 km s −1 for O +. This is larger than that observed in the ionosphere immediately surrounding the hole. The minimum ion drift speeds in the hole regions are largest for O + and smallest for He + with C + and N + intermediate. The concentrations of light ion species are enhanced relative to heavier species inside the hole as is evidenced by the increase in the He +/O + ratio. The measurements of ion drift in the holes support the suggestion that they are regions of enhanced dynamic flow. Dynamic flows have also been measured in orbit 500 which has no outbound hole. An increase in the minimum flow speed to about 1 km s −1 is observed as the ionopause is approached from the ionosphere side. The implication is that ions are being accelerated out of the ionosphere by the electric and magnetic fields present in the ionosheath region. The direction of the ion flow cannot be determined but it can be bounded in the ecliptic plane. Ion flow directions for O + inferred in this manner from the data are consistent with downward (toward Venus) flow within the outbound holes of orbits 530–531 and upward flow near the ionopause for orbit 500 without a hole. However, horizontal flow with a downward or upward component, respectively, cannot be excluded by the measurements.

Whistler waves associated with the Uranian bow shock: Outbound observations

The encounter of the Voyager 2 spacecraft with the Uranian planetary system led to a series of outbound crossings of the Uranian bow shock between January 27 and January 30 of 1986. Examination of magnetic field data recorded in close proximity to the shock reveals a series of whistler wave events that appear to result from processes associated with the shock. Two wave events display two separate and simultaneous wave enhancements each, one at approximately 0.2 Hz and the second more nearly at 1 Hz in the spacecraft reference frame. The actual frequencies of the waves vary with the two events. Both wave enhancements of the two events are right‐hand polarized in the spacecraft frame of reference. We have examined these wave events using high‐resolution magnetic field data and conclude that they are analogous to those whistler waves upstream of the Earth's bow shock that are driven by beams of electrons. Using observations by the plasma wave science experiment on Voyager 2 to infer the likely presence of electron beams with modest beam speeds, we present an instability analysis and show that a single electron beam with reasonable parameters can generate both of the observed whistler wave forms simultaneously. A third wave event is also seen which occurs both upstream and downstream of a shock crossing. This event displays only one relatively broad spectral enhancement in the same frequency regime and is left‐hand polarized in the spacecraft frame. We argue that this event is most likely the result of a gyrating proton distribution associated with the oblique shock. As such, it is analagous to whistler waves observed earlier during the inbound crossing of the Uranian shock.

A theory for low‐frequency waves observed at comet Giacobini‐Zinner

As the ICE spacecraft approached comet Giacobini‐Zinner, low‐frequency waves in two frequency ranges were observed in the magnetic field data. We show that, under certain conditions, a gyrating beam of water group ions is capable of generating electromagnetic waves with periods near 100 s (in the spacecraft frame of reference) and shorter‐period whistler branch waves with periods near 3 s. The 100‐s wave can arise from either a nonresonant firehose instability or a resonant beam driven instability so long as the angle between the directions of the local magnetic field and solar wind velocity is less than 90°. Whenever that angle exceeds about 30°, the gyrating ring distribution formed by newly ionized water is also unstable to the generation of whistler waves with 3‐s periods.

Low‐frequency waves and associated energetic ions downstream of Saturn

Coherent, low‐frequency waves were observed occasionally in the interplanetary magnetic field (IMF) by Voyager 2 during 5 months in 1981–1982 following its encounter with Saturn. These waves had periods ranging from 1.4 to 2.8 hours in the spacecraft reference frame (frequencies near 10−4 Hz) and were detected at distances ranging from 150 to 2800 RS (9.0×106 to 1.7×108 km) from Saturn. The waves were characterized by large‐amplitude fluctuations in both magnitude and direction of B, an ellipticity &gt;0.5 on average, and in most cases have been interpreted to have right‐hand polarization in the plasma frame. Although there was at best only a weak signature of these waves in the low‐energy (&lt;6 keV) plasma, large enhancements were observed in the count rate of energetic (28–80 keV) ions in association with wave occurrences out to a distance of ∼1300 RS (7.8×107 km) from Saturn. The distribution of the enhanced ions was highly anisotropic, with the highest count rates measured in the 45° sector most nearly facing Saturn. The observation of ion enhancements was found to depend on the latitude angle of the IMF. It is concluded that the waves were excited by energetic plasma ions propagating away from Saturn. They are similar to waves produced upstream of earth by ions reflected from the bow shock or escaping from the magnetosphere. Because of the unique combination of IMF orientation at Saturn's orbit and the Voyager 2 postencounter trajectory, these observations represent the most remote detection of such planet‐associated (foreshock) waves. It is shown that viable mechanisms for exciting such waves under the given conditions include two beam‐driven resonant cyclotron instabilities as well as the nonresonant firehose instability. The absence of any strong signature of these waves in the thermal plasma suggests that the magnetic field fluctuations may arise from the firehose instability.

Correction to “Turbulence analysis of the Jovian upstream ‘wave’ phenomenon”

Journal of Geophysical Research: Space PhysicsVolume 89, Issue A10 p. 9159-9160 CorrectionsFree Access Correction to “Turbulence analysis of the Jovian upstream ‘wave’ phenomenon” Charles W. Smith, Charles W. SmithSearch for more papers by this authorMelvyn L. Goldstein, Melvyn L. GoldsteinSearch for more papers by this authorWilliam H. Matthaeus, William H. MatthaeusSearch for more papers by this authorAdolfo F. Viñas, Adolfo F. ViñasSearch for more papers by this author Charles W. Smith, Charles W. SmithSearch for more papers by this authorMelvyn L. Goldstein, Melvyn L. GoldsteinSearch for more papers by this authorWilliam H. Matthaeus, William H. MatthaeusSearch for more papers by this authorAdolfo F. Viñas, Adolfo F. ViñasSearch for more papers by this author First published: 1 October 1984 https://doi.org/10.1029/JA089iA10p09159Citations: 46AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume89, IssueA101 October 1984Pages 9159-9160 ReferencesRelatedInformation

An electric noise component with density f−1 identified on ISEE 3

An electric noise component with an f−1 spectrum is observed with the SBH radioastronomy receivers on ISEE 3 at frequencies lower than the plasma frequency fp. On the Z antenna (electrical length for long waves is 7 m) this component is 5–10 times more intense than the predicted thermal noise level. Its spectral density is proportional to fpf−1(Tc)1/2, where Tc is the core electron temperature and f is the observing frequency. On the S antenna (90 m tip to tip) the new component is much weaker and most probably represents the high‐frequency part of a noise spectrum found by Kellogg (1981) with an antenna of the same length. This author interpreted it as mostly due to electron acoustic waves and Doppler shifted ion acoustic waves, but this interpretation has not been confirmed by more accurate calculations (Couturier et al., 1982). Kellogg's spectrum also shows an f−1 frequency dependence and, if extrapolated assuming the same law as for the Z antenna, approximately fits our S antenna observations. The S antenna f−1 noise is deeply spin modulated with the minimum electric field in the direction of the solar wind flow as seen in the spacecraft frame of reference. The modulation factor decreases with increasing frequency, becomes negligible when the new component intensity becomes negligible as compared with thermal noise, and increases with the solar wind velocity. The f−1 component shows some of the properties which are expected from shot noise (direction of minimum intensity) but its spectral index is −1 while shot noise is supposed to show a spectral index −2.

Characteristics of the ULF waves associated with upstream ion beams

This report describes a new class of upstream wave with relatively high frequencies (∼1 Hz in the spacecraft frame of reference) and small amplitudes (1/2;γ peak to peak) compared with the more common larger amplitude (ΔB/B ∼ 1), low‐frequency (0.03 Hz) upstream waves. These waves were first noted in association with beams of ions reflected back upstream at the bow shock, appearing in conjunction with some but not all of such beams. Further work confirms the association of the waves with the beams: the presence of a beam appears to be a necessary condition for the observation of the waves. Beam presence is, however, not a sufficient condition for existence of the waves and no clear correlation has been found between beam properties and the presence or absence of the waves. We have used characterizations of the beams provided by the ISEE 1 and 2 LEPEDEA plasma analyzers along with wave profiles obtained by the ISEE 1 and 2 magnetometers in probing these relationships. In addition, measurements made by the magnetometers were used to determine the intrinsic properties of these waves, using the simultaneous two point measurements to calculate and eliminate Doppler shifting effects. Results demonstrate that these are right‐hand elliptically polarized whistler mode waves with plasma rest frame frequencies of 20–100 times the proton gyrofrequency and wavelengths ∼100 km. The waves tend to propagate in the plane formed by the local IMF direction and the solar wind at angles ∼45° with respect to the magnetic field direction. Group velocities estimated from cold plasma theory for waves of these frequencies traveling in the observed directions are often not sufficient to allow the waves to reach the spacecraft at the times of observation. This argues against the possibility that the waves could have propagated upstream to the spacecraft position from the bow shock itself.