Helios
German-American spacecraft orbiting the sun
Helios 1 and Helios 2 were a pair of deep space probes
developed by the Federal Republic of Germany (FRG) in a cooperative
program with NASA. Experiments were provided by scientists from both FRG
and the U.S. NASA supplied the Titan/Centaur launch vehicle. Each
spacecraft was equipped with two booms and a 32 m electric dipole.
The payload consisted of a fluxgate magnetometer; electric and magnetic
wave experiments, which covered various bands in the frequency range
6 Hz to 3 MHz; charged-particle experiments, which covered
various energy ranges starting with solar wind thermal energies and
extending to 1 GeV; a zodiacal-light experiment; and a
micrometeoroid experiment. The purpose of the mission was to make
pioneering measurements of the interplanetary medium from the vicinity
of the earth's orbit to 0.3 AU. The spin axis was normal to the
ecliptic, and the nominal spin rate was 1 rps. Instrument
descriptions written by the experimenters were published in Raumfahrtforschung 19/5 (1975).
Data Examples
- Selected 3-D proton velocity distribution functions from
Helios 2.
E1 instrument 1A, plots by H. F. Astudillo:
 local
 original
-
Example of a
shock, magnetic cloud and bidirectional electrons seen by
Helios 1 on March 1-3, 1978.
E1 and E2 instruments, plot by K. Ivory.
(
PostScript)
![[Top]](/images/icons/top.gif)
Data availability
The largest data base of
Helios data
available on the World Wide Web is provided by the National Space Science Data
Center (
NSSDC). Hourly Helios 1
& 2 plasma and magnetic field data are contained within the
COHOWeb interface. The value
of COHOWeb, besides its data subsetting and graphical display functionalities,
is that each of many deep space spacecraft (Ulysses, Voyagers 1&2,
Pioneers 10&11, etc.) have common data records (IMF vectors in a common
coordinate system, s/c position vectors in a common coordinate system, etc.).
This is an excellent starting point for multipoint studies of interplanetary
phenomena (spatial structures and evolutions of interplanetary shocks, CME's,
etc.).
Plots of the Helios mission
heliocentric trajectories.
E1 Plasma Experiment
Principal investigator: H. Rosenbauer
The plasma experiment aboard the Helios solar probes consists of four
independent instruments designed to investigate the solar wind plasma.
By measuring the velocity distribution functions of the different kinds
of particles, all important hydrodynamic parameters of the solar wind plasma
can be derived. Three instruments (I1a, I1b, and I3) analyze the positive
components (protons and heavier ions with energy-per-charge values from 0.155
to 15.32 kV) of the solar wind. Two of them allow for an angular
resolution in both directions of incidence. One instrument (I2) measures
electrons in the energy range from 0.5 the 1660 eV with one-dimensional
angular resolution.
E2 Flux-gate Magnetometer
Principal investigator: F. B. Neubauer
The flux-gate magnetometer experiments use triaxial, orthogonal flux-gate
sensors of the Forster type mounted on a boom of about 2 m from the
spacecraft. The bandwidth is 4 Hz. Two measuring ranges are used with
automatic switching. The sensitivity range extends from -100 nT to
+100 nT.
Helios E1 and E2 data on magneto-optical discs (MOD) at MPS
The complete merged data set for the plasma experiment E1 and
magnetometer experiment E2 for both Helios 1 and Helios 2 is
available for local use at MPS on 19 MODs. The E2 data is averaged to
match the time resolution of the E1 data. (Highest time resolution:
40.5 s/spectrum.)
Helios E1 and E2 data on compact disc (CD-ROM) at MPS
Selected parameters of the complete data set (19 MODs) have been
compressed to fit on one CD. Documentation
- Credits
- Directory structure
- File structure of table files
- File structure of binary files
- Appendix: ISO 9660 Filesystem
E5a Plasma Wave Experiment
Principal investigator: D. A. Gurnett
The University of Iowa
plasma
wave experiment (E5a) utilized the 32 m tip-to-tip dipole antenna to
detect the electric component of plasma waves.
E6 Cosmic Ray Experiment
Principal investigator: H. Kunow
The cosmic ray
particle
experiment E6 (University of Kiel) consists of a detector telescope
containing five semiconductor detectors of increasing thickness, a sapphire
Cerenkov deteector surrounded by an anticoincidence scintillation detector,
and an on-board handling system. The instrument is capable of measuring
protons and heavier nuclei from 1.7 to more than 400 MeV/n and MeV
electrons.
E8 Low-Energy Electron and Ion Spectrometer
Principal investigator: E. Keppler
The spectrometer utilizes an inhomogenous magnetic field for separation of
charged particles. Protons (and heavier particles) traverse the magnetic field
almost unaffected and are detected in a telescope arrangement consisting of
two semiconductor detectors. Electrons are focused and detected by four
semiconductor detectors. Positrons (if present) are deflected in the opposite
direction and detected in another detector.
|
raw text version