Earth Sun Planets and Moons ID: 3595

Sentinels of the Heliosphere

Visualizations by Greg Shirah Released on July 27, 2009

Heliophysics is a term to describe the study of the Sun, its atmosphere or the heliosphere, and the planets within it as a system. As a result, it encompasses the study of planetary atmospheres and their magnetic environment, or magnetospheres. These environments are important in the study of space weather.

As a society dependent on technology, both in everyday life, and as part of our economic growth, space weather becomes increasingly important. Changes in space weather, either by solar events or geomagnetic events, can disrupt and even damage power grids and satellite communications. Space weather events can also generate x-rays and gamma-rays, as well as particle radiations, that can jeopardize the lives of astronauts living and working in space.

This visualization tours the regions of near-Earth orbit; the Earth's magnetosphere, sometimes called geospace; the region between the Earth and the Sun; and finally out beyond Pluto, where Voyager 1 and 2 are exploring the boundary between the Sun and the rest of our Milky Way galaxy. Along the way, we see these regions patrolled by a fleet of satellites that make up NASA's Heliophysics Observatory Telescopes. Many of these spacecraft do not take images in the conventional sense but record fields, particle energies and fluxes in situ. Many of these missions are operated in conjunction with international partners, such as the European Space Agency (ESA) and the Japanese Space Agency (JAXA).

The Earth and distances are to scale. Larger objects are used to represent the satellites and other planets for clarity.

Here are the spacecraft featured in this movie:

Near-Earth Fleet:

Hinode: Observes the Sun in multiple wavelengths up to x-rays. SVS page
RHESSI : Observes the Sun in x-rays and gamma-rays. SVS page
TRACE: Observes the Sun in visible and ultraviolet wavelengths. SVS page
TIMED: Studies the upper layers (40-110 miles up) of the Earth's atmosphere.
FAST: Measures particles and fields in regions where aurora form.
CINDI: Measures interactions of neutral and charged particles in the ionosphere.
AIM: Images and measures noctilucent clouds. SVS page

Geospace Fleet:

Geotail: Conducts measurements of electrons and ions in the Earth's magnetotail.
Cluster: This is a group of four satellites which fly in formation to measure how particles and fields in the magnetosphere vary in space and time. SVS page
THEMIS: This is a fleet of five satellites to study how magnetospheric instabilities produce substorms. SVS page

L1 Fleet:

The L1 point is a Lagrange Point, a point between the Earth and the Sun where the gravitational pull is approximately equal. Spacecraft can orbit this location for continuous coverage of the Sun.

SOHO: Studies the Sun with cameras and a multitude of other instruments. SVS page
ACE: Measures the composition and characteristics of the solar wind.
Wind: Measures particle flows and fields in the solar wind.

Heliospheric Fleet

STEREO-A and B: These two satellites observe the Sun, with imagers and particle detectors, off the Earth-Sun line, providing a 3-D view of solar activity. SVS page

Heliopause Fleet

Voyager 1 and 2: These spacecraft conducted the original 'Planetary Grand Tour' of the solar system in the 1970s and 1980s. They have now travelled further than any human-built spacecraft and are still returning measurements of the interplanetary medium. SVS page

This enhanced, narrated visualization was shown at the SIGGRAPH 2009 Computer Animation Festival in New Orleans, LA in August 2009; an eariler version created for AGU was called NASA's Heliophysics Observatories Study the Sun and Geospace.

The movie opens on the date of November 1, 2006, with a view of the inner Solar System. We see the Sun, as well as the orbits of Mercury, Venus, Earth (in blue) and Mars. We zoom in towards the Earth.

As we approach the Earth, we get a wide view of the spacecraft located at L1 as well as the Earth nestled within the magnetosphere. The magnetosphere forms due to the interaction of the Earth's geomagnetic field with the plasma of the solar wind. Solar wind pressure drags the magnetosphere back from the Earth, away from the Sun, much like a 'wind sock'. For convenience, arrows remind us of the direction of the Sun (yellow) and the direction that the Earth travels along its orbit (blue).

Moving closer to the Earth, we see the orbit of the Moon. We also see the orbits of several spacecraft in the region between the Earth and the Moon's orbit.

We fly throught the boundary of the magnetosphere for a closeup view of the Earth (note that the clouds are changing, updating based on weather satellite imagery from this time). We also see the orbits of heliofleet satellites that occupy near-Earth orbit. Here, the fleet include not only Earth-observing missions like TIMED and FAST, but solar observatories as well: TRACE, RHESSI, and Hinode.

Passing back through the boundary of the magnetosphere, we can now see the satellites, Geotail and Cluster, that patrol this region measuring the particles and fields. Cluster (actually Cluster II), is a group of four identical satellites that fly in formation through this region.

As we continue our pull-out, we see the two STEREO satellites, STEREO-A and B, shortly after launch, while still in their post-launch phasing orbit which travels from the Earth to the orbit of the Moon.

Here we get a geospace family portrait: the Earth and Moon, as well as the satellites Cluster, Geotail, and STEREO-A and B.

The spacecraft STEREO-A and B make their first lunar flyby, using the Moon for a gravity-assist. For STEREO-A, the flyby transfers enough momentum to send the satellite into a solar orbit, slightly closer to the Sun than the Earth. From this orbit, STEREO-A becomes STEREO-Ahead as it begins to move ahead relative to the Earth in its orbit.

The Moon completes another orbit before it encounters STEREO-B for its second lunar flyby. This encounter sends STEREO-B into an orbit further from the Sun than the Earth, where STEREO-B will become STEREO-Behind as it drops behind the Earth in relative position along its orbit.

From a vantage point 'above' and 'behind' the Earth, we look sunward to the three spacecraft that 'orbit' around an empty point in space - the Sun-Earth Lagrange Point, L1.

Now we take a spin around the L1 point, observing SOHO, ACE, and Wind as they execute their trajectories around this location. Because L1 is actually an unstable point, the spacecraft need occasional trim maneuvers to maintain their location. We speed up time as we orbit, also noting that the L1 point seems to execute small oscillations in the yellow Earth-Sun marker. These oscillations are due to the gravitational tug of the Moon as it orbits the Earth. After spending over a year at L1, we return to the Earth to see what is new...

Returning to the geospace around the Earth, we see a new mission has come on the scene - THEMIS, with five identical spacecraft, travel in a series of aligned elliptical orbits to sample the Earth's magnetotail at different distances.

We continue our approach to Earth, and observe the region patrolled by THEMIS, the five satellites designated with the letters A through E.

Special version (more readable) rendered for SIGGRAPH2009 submission.

We continue our approach to Earth, and observe the region patrolled by THEMIS, the five satellites designated with the letters A through E.

Passing through the magnetosphere again, we see two new missions in near-Earth orbit: C/NOFS carries the CINDI instrument for observing the ionosphere while AIM observes noctilucent clouds.

Finally, we pull out from the Earth, traversing the space covered many years ago by the Pioneers and Voyagers...

Two light blue paths appear, terminating on the orbit of the Earth. They represent the trajectories of Voyager 1 and Voyager 2, launched in September and August, respectively, of 1977.

We see the changes in the trajectories of the Voyagers as they cross the orbits of the giant planets Jupiter and Saturn. With the Saturn encounter, Voyager 1 is sent out of the plane of the Solar System, called the Ecliptic.

Voyager 2 continued in the Ecliptic, making historic flybys of the planets Uranus and Neptune, The Neptune flyby is used to direct Voyager 2 below the Ecliptic, enabling it to explore a different region than Voyager 1.

It is now believed that both Voyagers have crossed the termination shock for the helipause, the innermost boundary that separates the environment of our Solar System from the interstellar medium.

The heliopause and the bowshock are the two remaining 'surfaces' for the Voyagers to cross, the regions defined by characteristics of the solar wind's interaction with the interstellar medium. The transmitters on the Voyagers are expected to still be operating when they cross the heliopause, estimated to be around 2015.

Visualization Credits

Greg Shirah (NASA/GSFC): Lead Animator
Ernie Wright (UMBC): Animator
Tom Bridgman (Global Science and Technology, Inc.): Animator
Horace Mitchell (NASA/GSFC): Animator
Trent L. Schindler (UMBC): Animator
Cindy Starr (Global Science and Technology, Inc.): Visualizer
Stuart A. Snodgrass (HTSI): Video Editor
Michael Starobin (HTSI): Narrator
Rani Gran (NASA/GSFC): Producer
Jeffrey Hayes (NASA/HQ): Scientist
Jennifer Rumburg (NASA/OSC): Scientist
Michael Starobin (HTSI): Writer

Please give credit for this item to:
NASA/Goddard Space Flight Center Scientific Visualization Studio

Short URL to share this page:
https://svs.gsfc.nasa.gov/3595

Missions:
ACE
AIM
CINDI
Hinode (Solar-b)
Mercury
RHESSI
SOHO
STEREO
THEMIS
TIMED
TRACE
Voyager
Wind

Data Used:

Hipparcos/Telescope/Hipparcos Catalogue

Database

http://www.rssd.esa.int/index.php?project=HIPPARCOS

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Hipparcos/Telescope/Tycho 2 Catalogue also referred to as: Tycho Catalogue

Database

http://archive.eso.org/ASTROM/

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CPC (Climate Prediction Center) Cloud Composite

Data Compilation - Climate Prediction Center (CPC)

Global cloud cover from multiple satellites

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SSCweb also referred to as: SSCweb ephemerides

Ephemeris - NASA/GSFC Space Physics Data Facility - November 1, 2006 - September 30, 2008

Satellite ephemerides

http://sscweb.gsfc.nasa.gov

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Advanced Composition Explorer (ACE)

http://www.srl.caltech.edu/ACE/

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C/NOFS/Coupled Ion Neutral Dynamics Investigation (CINDI)

http://cindispace.utdallas.edu/

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TOPEX/Poseidon/Sea Surface Height Anomaly

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Cluster

http://sci.esa.int/science-e/www/area/index.cfm?fareaid=8

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JPL/Horizon Orbital Ephemerides

Ephemeris - NASA/JPL - November 1, 2006 - September 30, 2008

Planetary ephemerides

http://ssd.jpl.nasa.gov/?horizons

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THEMIS

http://themis.ssl.berkeley.edu/index.shtml

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STEREO

The STEREO mission consists of two Sun-observing spacecraft that will travel around the Sun on orbits slightly inside and slightly outside Earth's orbit.

https://stereo.gsfc.nasa.gov

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Wind/MFI

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TRACE

The TRACE satellite views the Sun at ultraviolet wavelengths with high temporal (approximately 1-12 seconds) and spatial (1 arcsecond per pixel) resolution. Launched on April 2, 1998, it orbits the Earth in a Sun-synchronous orbit.

http://sunland.gsfc.nasa.gov/smex/trace/

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TIMED

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RHESSI/X-ray Imaging Spectrometer

The RHESSI instrument is an imaging spectrometer observing the Sun at X-ray to gamma-rays (photon energies of 3 keV to 17 MeV) at time resolutions of a few seconds. (eV stands for "electron volt" and is a unit of energy. Note that photons of visible light have energies of 2-3 eV. 1 keV is a thousand electron volts and 1 MeV is a million electron volts.

http://hesperia.gsfc.nasa.gov/hessi/

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