Computer simulation predicts Voyager 2 will reach major milestone in space in late 2007-early 2008

Nov 27, 2007
An artist's concept of Voyager 1.
An artist's concept of Voyager 1.

Using a computer model simulation, Haruichi Washimi, a physicist at UC Riverside, has predicted when the interplanetary spacecraft Voyager 2 will cross the “termination shock,” the spherical shell around the solar system that marks where the solar wind slows down to subsonic speed.

According to Washimi’s simulations, the spacecraft is set to cross the termination shock in late 2007-early 2008. To make this forecast, Washimi and his colleagues used data from Voyager 2 and performed a global “magneto-hydrodynamic simulation” – a method that allows for precise and quantitative predictions of geomagnetic disturbances caused by solar activities.

Because Voyager 2’s crossing of the shock is expected to be an abrupt and relatively brief event, scientists are working to ensure that the most is made of the opportunity. With an idea of when the spacecraft will cross the shock, they are better able to maximize coverage of the crossing.

Study results appear in the Dec. 1 issue of The Astrophysical Journal.

“Washimi’s model has predicted the location of a boundary that is approximately 90 times farther from the sun than is the Earth, to within a few percent,” said Gary Zank, the director of the Institute of Geophysics and Planetary Physics and one of the coauthors of the research paper. “This is truly remarkable given the enormous complexity of the physics involved, the temporal and spatial scales involved, and the variability of the solar wind conditions.”

The solar wind – a stream of charged particles ejected by the sun in all directions – travels at supersonic speeds when it leaves the sun, until it eventually encounters the interstellar medium made up of plasma, neutral gas and dust.

At the termination shock, located at 7-8.5 billion miles from the sun, the solar wind is decelerated to less than the speed of sound. The boundary of the termination shock is not fixed, however, but wobbly, fluctuating in both time and distance from the sun, depending on solar activity.

“This is the first time the termination-shock position has been forecast in this way,” said Washimi, the lead author of the research paper and a scientist at the Institute of Geophysics and Planetary Physics. “After it crosses this boundary, Voyager 2 will be in the outer heliosphere beyond which lies the interstellar medium and galactic space. Our simulations also show that the spacecraft will cross the termination shock again in the middle of 2008. This will happen because of the back and forth movement of the termination-shock boundary. This means Voyager 2 will experience multiple crossings of the termination shock. These crossings will come to an end after the spacecraft escapes into galactic space.”

Voyager 2 was launched Aug. 20, 1977. It visited four planets and their moons in the course of its journey into space. Its sister spacecraft Voyager 1, which was launched Sept. 5, 1977, crossed the termination shock in December 2004 – earlier than Voyager 2 because of a shorter trajectory. Both spacecraft are currently operational, but power sources have degraded and some of the instrumentation no longer works optimally. In the future, the spacecraft will encounter their next milestone in space: the heliopause, which is the boundary where the interstellar medium brings the solar wind to a halt.

Source: University of California - Riverside

Explore further: It's 'full spin ahead' for NASA soil moisture mapper

Related Stories

UA-led HiRISE camera spots long-lost space probe on Mars

Jan 16, 2015

The UK-led Beagle 2 Mars Lander, thought lost on Mars since 2003, has been found partially deployed on the surface of the planet, ending the mystery of what happened to the mission more than a decade ago. ...

Recommended for you

Cassini: Return to Rhea

8 hours ago

After a couple of years in high-inclination orbits that limited its ability to encounter Saturn's moons, NASA's Cassini spacecraft returned to Saturn's equatorial plane in March 2015.

Comet dust—planet Mercury's 'invisible paint'

15 hours ago

A team of scientists has a new explanation for the planet Mercury's dark, barely reflective surface. In a paper published in Nature Geoscience, the researchers suggest that a steady dusting of carbon from p ...

It's 'full spin ahead' for NASA soil moisture mapper

18 hours ago

The 20-foot (6-meter) "golden lasso" reflector antenna atop NASA's new Soil Moisture Active Passive (SMAP) observatory is now ready to wrangle up high-resolution global soil moisture data, following the successful ...

What drives the solar cycle?

18 hours ago

You can be thankful that we bask in the glow of a relatively placid star. Currently about halfway along its 10 billion year career on the Main Sequence, our sun fuses hydrogen into helium in a battle against ...

MESSENGER completes 4,000th orbit of Mercury

18 hours ago

On March 25, the MESSENGER spacecraft completed its 4,000th orbit of Mercury, and the lowest point in its orbit continues to move closer to the planet than ever before. The orbital phase of the MESSENGER ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

earls
not rated yet Nov 28, 2007
Dare I say there's a lot riding on this.
Reaper6971
not rated yet Nov 28, 2007
Dare... dare
am_Unition
not rated yet Nov 28, 2007
And there is, methinks.

What kind of direct observation data do we have on interstellar dust densities outside the heliosphere? Intragalactic magnetic field strength? Boundary conditions at the heliopause? How/if intragalactic magnetic fields and interglactic dust regulate star output or cycles?
eschaton
not rated yet Nov 29, 2007
I wish they included what information they expected to get from this. I think about all they can get from these crafts any more is telemetry data.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.