| |
CX7BY > SAT 16.11.03 02:22l 79 Lines 3379 Bytes #999 (0) @ AMSAT
BID : ANS-320.04
Read: GUEST
Subj: Voyager near edge of solar system
Path: DB0FHN<DB0FOR<DB0SIF<DB0SON<DB0ERF<DB0FBB<DB0GOS<ON0AR<WB0TAX<7M3TJZ<
CX2ACB<CX7BY
Sent: 031115/2352Z @:CX7BY.MVD.URY.SA #:60375 [Montevideo] FBB $:ANS-320.04
From: CX7BY@CX7BY.MVD.URY.SA
To : SAT@AMSAT
AMSAT News Service Bulletin 320.04 From AMSAT HQ
SILVER SPRING, MD. November 16, 2003
To All RADIO AMATEURS
BID: $ANS-320.04
Voyager 1 is doing some cosmic surfing, riding a boundary called the
termination shock as it nears the edge of the solar system. It's the
first spacecraft to fly so far.Scientists don't agree on exactly why
solar winds suddenly slowed around Voyager for about six months
starting in summer 2002. The spacecraft may have crossed the
fluctuating boundary where the solar system begins to push up against
interstellar space.
"This is a totally new region, and that's the reason you see this
scientific discussion going on, as people explore how to understand
this unusual nature of these observations," said Voyager project
scientist Edward Stone of California Institute of Technology in
Pasadena.
The twin Voyager craft launched in 1977 from Cape Canaveral to explore
the outer planets. Their nuclear power supply should work until 2020.
Scientists hope their instruments will last that long and that Voyager
1 will reach interstellar space while it can still send back data.
The solar system is nestled in a kind of bubble in which the sun is
king, the heliosphere. Supersonic solar winds radiate out from the sun,
creating this bubble, and where they start to hit interstellar forces
and suddenly slow down is called the termination shock.
Although Voyager 1's solar wind instrument stopped working in 1980,
scientists inferred from other data that the solar wind slowed
dramatically in August 2002. There were indications that the spacecraft
was amid interstellar matter, as well, said Stamatios "Tom" Krimigis
of Johns Hopkins University's Applied Physics Laboratory.
His team found during that time, Voyager 1 traveled beyond the
termination shock into the heliosheath, the outer envelope of the
heliosphere. Then it was overtaken by the boundary and was back among
the supersonic solar winds.
The University of Maryland's Frank McDonald, however, said there should
have been other significant changes if Voyager hit the shock.
"This is sort of a Lewis and Clark space expedition," McDonald said.
"We're in the foothills, and we'll soon be getting to the mountains, in
our view."
Either way, both teams of scientists think Voyager is on the edge of
the bubble and moving out. It is now nearly 8.4 billion miles from the
sun.
"I think we'll be surfing along the shock and see it a number of times,
and as we do, we will confirm what is the signature of the shock,"
Stone said.
Beyond the heliosheath is interstellar space. After Voyager 1 crosses
the termination shock, it could take several years for the craft to
pass through the heliosheath and finally leave our solar system.
Voyager 2, on a different path, will take even longer to get there.
It is thought that as our solar system passes through clouds of
material in our Milky Way galaxy, it creates a bow shock beyond the
heliosphere, the way a ship creates a bow wave.
It's important to know the nature of this material, said Jet Propulsion
Laboratory research scientist Merav Opher, because it helps determine
the shape and size of our solar system.
With Voyager, she said, "it's like we're piercing a hole in the
curtain that separates us from the rest of the galaxy."
[ANS thanks Florida Today for the above information.]
Read previous mail | Read next mail
| |
