The figure illustrates many of the important features of the solar modulation of anomalous cosmic rays (ACRs) and also gives us a forecast for the coming years. Panel (a) shows the intensity of ACR O at 1 AU as measured by a variety of observers over the last 30 years. The SAMPEX measurements are the

During May there were several spacecraft anomalies: The Polar spacecraft anomaly coincided with the rise phase of an solar energetic particle event on May 6, and was likely caused by a Single Event Upset (SEU) from energetic heavy ions from the solar particles While the causes of the Equator-S and Galaxy-4 failures are yet undetermined,

A significant coupling has been proposed to exist between solar activity, energetic electron precipitation (EEP) from the magnetosphere into the atmosphere followed by NOy formation with its transport to the stratosphere possibly altering stratospheric O3. The verification of this solar-terrestrial coupling requires three essential findings. (1) Show that precipitating electrons respond to solar forcing, in

The LICA ion spectrometer on SAMPEX routinely detects quasi-trapped protons near the magnetic equator. Such low-altitude, equatorial ions first were observed by Moritz (1972) and Hovestadt et al. (1972) with instruments on the Azur satellite. The ions typically have pitch angles near 90 degrees, because more field-aligned ions are rapidly lost to collisions with the

Several magnetic cloud/CME events have been observed during the 1997-98 time period, as we approach the maximum of the next solar cycle. Multiple spacecraft have observed for the first time the evolution of these events from their origin to passage over the magnetosphere. We have studied the magnetospheric outer zone energetic electron response to these

The observations of time scales for high energetic electrons throughout the terrestrial radiation belts are of great interest in magnetospheric physics. These electrons also have a large practical importance because of their potential hazard on spacecraft subsystems. SAMPEX data show an abrupt electron enhancement throughout the=20 magnetosphere on a time scale of one and two

Using the MAST instrument on SAMPEX, we have measured the average charge state of iron at energies of 28-50 MeV/nucleon in the November 6, 1997 solar energetic particle (SEP) event. This measurement was made by finding the latitude distribution of particles and relating it to the geomagnetic cutoff rigidity which, together with the measured=20 mass

The principal source of high energy (>10 MeV/nuc) heavy ions with Z>=3 in Earth’s radiation belts is anomalous cosmic rays (ACRs), an interplanetary component of particles that originates from interstellar atoms that have been accelerated at the solar wind termination shock. Interplanetary ACRs become trapped when they are stripped of their remaining electrons in passing

In order to probe the physical mechanisms for large radiation belt intensity enhancements during geomagnetic storms, variations in 0.2-3.2 MeV electron flux in the magnetosphere during the May 15, 1997 magnetic storm (the largest magnetic storm of 1997) have been examined using data from SAMPEX, GPS series of satellites, and LANL sensors on geosynchronous orbit.

The Proton/Electron Telescope (PET) aboard SAMPEX uses multiple energy-deposit and range measurements to identify electrons and light nuclides unambiguously over a wide energy range, which enables us to detect rare species even in regions of the magnetosphere with high fluxes of more abundant particles. In particular, the shock of 24 March 1991 injected a long-lasting

Anomalous cosmic rays (ACR) are a sample of the local interstellar medium. ACRs begin as neutral atoms with high first ionization potential (e.g. He, O, Ne, Ar) that drift into the heliosphere, become singly ionized by solar UV or collisions with the solar wind, and then are accelerated to beyond 10 MeV/nucleon at the termination

The Mass Spectrometer Telescope (MAST) instrument on SAMPEX, which was built by Caltech and GSFC, is designed to measure the elemental and isotopic composition of nuclei from He to Ni (Z = 2 to 28) over the energy range from ~15 to 200 MeV/nuc. Analysis of MAST data in other Solar Energetic Particle (SEP) events

The pleasantly surprising fact that SAMPEX has continued to operate well beyond its minimum design lifetime has provided a remarkable, long-term view of high-energy electrons throughout the Earth’s Van Allen radiation belts. The accompanying figure plots the logarithm of electron flux in the 2-6 MeV energy range as a color-coded representation. Data are plotted in

On 24 March 1991, the CRRES spacecraft observed the creation of a new radiation belt in a time period of less than 90 seconds. This belt was created by an intense shock in the interplanetary medium, and consisted of electrons with energies above 15 MeV and protons of comparable energy. This completely unexpected observation aroused

Essentially all 2-D models used for the assessments of the effects of mankind on global ozone include only the oxidation of N2O (a naturally occurring source gas) as a source of reactive nitrogen compounds in the stratosphere. These odd nitrogen compounds (NO, NO2 and others) are essential to the maintenance of the balance of global

The figure shows the intensity of anomalous cosmic ray (ACR) O at 1 AU as measured by a variety of observers over the last 30 years. The SAMPEX measurements are the green boxes. The solid line is proportional to the Climax neutron monitor rate (from the University of Chicago) raised to the 25th power. This

SAMPEX’s 82 degree inclination low-Earth orbit is ideal for direct determination of the geomagnetic cutoffs for ions with energies ~1-100 MeV/nucleon. By observing the cutoff of ion intensities each time the spacecraft passes through the polar cap boundary, a time history of cutoff values can be compiled for each solar particle event. During the November

SAMPEX’s high inclination, low altitude polar orbit was designed to determine the ionic charge composition of Anomalous Cosmic Rays (ACR). It was found that ACRs (N, O, and Ne) below ~ 350 MeV are predominantly singly ionized, thus confirming the hypothesis of interstellar neutrals being the source of ACRs. At higher energies, however, multiply charged

In its 82 degree inclination orbit, SAMPEX crosses a polar cap and is exposed to interplanetary energetic particles twice each orbit. During intense solar energetic particle (SEP) events, count rates of high energy particles change from near zero at the equator (deep inside the geomagnetic field) to hundreds or thousands per second at the poles,

The finding of Paulikas and Blake in 1979 that the correlation between the solar wind speed and the >1 MeV electron flux at geostationary orbit depends strongly on the solar wind speed about a day before has been a puzzle especially since the solar wind velocity varies by only about a factor of two whereas

On 11 May 1999, the solar wind density (n) upstream of the Earth dropped down to less than 1.0 particle per cubic centimeter. In fact, for the latter portion of the day the solar wind density was less than (or near) 0.1 cm-3 at the same time that the solar wind speed (V) was less

As discussed in this space a few weeks back, in mid-May 1999 the density of the solar wind dropped well below 1 proton per cubic centimeter for a period of almost two days. The reduction of the ram pressure on the Earth’s magnetosphere caused it to balloon to several times its normal linear dimensions and

We have used the LICA sensor on board SAMPEX to create a picture of the low-altitude environment of ~1 MeV protons. The low-Earth orbit of SAMPEX enables us to detect protons from a number of sources. The LICA sensor has an extremely low efficiency for coincidence measurements of protons (much less than 0.1%). Nevertheless, with

We now have more than 7 years of trapped ACR data from SAMPEX including the minimum phase of the solar cycle, when the interplanetary ACR are most abundant, and the recent approach to solar maximum. The time dependence of the trapped ACR oxygen intensity is shown in red with 52-day time resolution at the top

Coronal mass ejections (CMEs) are observed to have significant effects in near-Earth space. Fast CMEs in May, September, and October of 1998 had strong interplanetary shock waves ahead of large magnetic cloud structures. It is important from a Sun-Earth connections standpoint to understand magnetospheric and atmospheric responses to CME/cloud events. The 1998 CME events were

A large solar particle event took place on Friday, July 14, commencing at 1012 UT with a X5.7/3B flare near the central meridian at N22W07. The event was in active region 9077. This event was the largest observed in 8 years of SAMPEX operations, surpassing the October/November 1992 events. Two shocks passed by Earth during

The figure shows the onset of the SEP event as seen by GOES 8 and SAMPEX; four polar cap traversals by SAMPEX are shown. Around 36000 sec UT SAMPEX saw a polar cap population of only the GCR. The onset of the SEP occurred just before SAMPEX entered the polar cap the next time at

One of the most studied natural forcings of stratospheric O3 is that due to solar UV flux variations. Despite the large number of studies devoted to the subject, questions still remain with regard to the calculated and observed sensitivity [S = (% change in O3} / (% change in UV flux near 200 nm)] of

Over most of the Space Station orbit, the astronauts are protected from exposure to low-energy cosmic rays and solar energetic particles by the Earth’s magnetic field. One way to express this shielding effect is with the so-called “geomagnetic cutoff”, by determining the minimum rigidity (or energy) particle that can penetrate to a given latitude. Most

It is well known that Relativistic electron flux enhancements are driven by High solar wind streams together with the southward turning of the IMF. Using SAMPEX data we have established important observational features of relativistic electron enhancements, namely, that they have a large L-shell extent and are nearly pitch-angle independent. That is, they exhibit global

In Earth orbit, low energy solar particles are excluded from low latitudes by the geomagnetic field, while over the poles they have free access. In an ongoing study, we use SAMPEX rate measurements in large solar energetic particle (SEP) events to determine the location of the transition between these two regions, known as the geomagnetic

The Earth’s magnetosphere efficiently accelerates and subsequently traps energetic particles. The outer radiation belt consists of electrons with energies of hundreds of keV to several MeV. SAMPEX has provided a picture of the radiation belts as a function of L (where L is the radial distance in Re at the equator if Earth’s magnetic field

We have examined signatures of two types of waves that may be involved in the acceleration of energetic electrons in the Earth’s radiation belts. First, ULF wave power from SAMNET and IMAGE ground magnetic observatories was compiled into a database. Second, VLF wave activity was obtained from low-altitude SAMPEX observations of electron microbursts, since these