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About Virtual COHO

The COHO interplanetary missions are in deep space and near-Earth orbits. Deep space differs from Near-Earth in that the spacecraft is far from Earth (either in the outer or inner part of our solar system). The measurements in the COHO database were hourly averaged, so each point represents an hour in time with the measurements (position, plasma temperature, plasma velocity, magnetic field, density) taken with instruments aboard various interplanetary spacecraft with NASA involvement. The COHO data uses the heliographic inertial (HGI) coordinate system of latitude, longitude, and distance with respect to the Sun, which is labeled at the origin.

[Virtual COHO Home Page / COHOWeb / Feedback]

The original HGI coordinate system used in the database was converted to a X-Y-Z coordinate system and translated into version 1.0 of the Virtual Reality Modeling Language (VRML). VRML allows one to navigate in this 3-D environment (our solar system) with a VRML viewer such as WebSpace or others that are freely available for most computing platforms (UNIX, PC, Mac). The colors in the visualization represent the values of scientific measurements scaled from 0 to 255 using a rainbow palette with violet-blue for low values and red-white as high values.

Deep Space Interplanetary Missions

For deep space examples see Ulysses (figure 1 below), Pioneer 10, Pioneer 11, Pioneer 12 (Pioneer Venus Orbiter), Voyager 1, Voyager 2, Helios-1, and Helios-2.

[Ulysses 3-D Model]
Figure 1. Ulysses - plasma velocity measurements

The Ulysses mission is for the first time exploring the high latitude heliosphere away from the plane of the ecliptic and over the solar poles. The primary objectives of the mission are to discover at these high latitudes the properties of the solar corona, the solar wind, the heliospheric magnetic field, solar energetic particles, galactic cosmic rays, solar radio bursts and plasma waves. Other investigations include study of cosmic dust, gamma ray bursts, and studies of the Jovian magnetosphere obtained during the Jupiter fly-by.

The screen snapshot shown in figure 1 was created from measurements taken aboard the Ulysses spacecraft from 1990 to 1993. The colors represent the plasma wave velocity measurements scaled from 0 to 255 with violet-blue for low values and red-white as high values. The position of Jupiter (annotated in Red) marks the Jupiter fly-by on Feb 8, 1992 and the position of Earth (annotated in Blue) marks the October 6, 1990 launch date.

[Ulysses 2-d Plot]
Figure 2. Ulysses - plasma velocity measurements and position

The 2-D time series in figure 2 was created with the COHOWeb data system and illustrates the same data in two dimensions as shown in figure 1 in three. Each model represents a different view of the data that may aid a researcher to interpret the meaning of data.

The Voyager 1 data measurements span 1977 to 1980, while the Pioneer Venus Orbiter (figure 3 below), Pioneer 10/11, and Voyager 2 data models represent measurements taken in 1979 from the corresponding spacecraft.

[PVO 3-D model]
Figure 3. Pioneer Venus Orbiter - magnetic field measurements

The Pioneer 12 spacecraft (also known as Pioneer Venus Orbiter) was inserted into an elliptical orbit around Venus on December 4, 1978. Note the circular orbit around the Sun that represents the spacecraft's orbit around Venus. In other words, the spacecraft orbits Venus as Venus revolves around the Sun.

Near-Earth Space Interplanetary Missions

For near-Earth examples see OMNI (IMP spacecraft series) with a geocentric orbit around the Earth.

[PVO 3-D model]
Figure 4. OMNI - plasma velocity measurements

[Virtual COHO Home Page / COHOWeb / Feedback]

Go to NSSDC Space Physics Home Page for more information about these and other flight projects.

VRML viewers can be obtained from SDSC's VRML Repository.

* Thanks to Daniel McCoy for selecting Virtual COHO as a Cool NASA Site of the Week.

The COHOWeb system was developed by Jason Mathews
and maintained by Dr. Natalia Papitashvili, Code 633, Greenbelt, MD 20771.
Last Update: September 21, 1995, GJM. NASA Official: Dr. Joseph H. King, Head, NSSDC.