Surpass 10,000 Days Of Operation
The intrepid twin Voyager spacecraft, launched about two
weeks apart in the summer of 1977 and now heading out of the
solar system, continue making history. On Jan.
5, 2005 the Voyager team noted a milestone with a nice
round number: 10,000 days since Voyager 2's launch. On Jan.
21, 2005 Voyager 1 also passed 10,000 days.
spacecraft are still going strong and are returning valuable
science data. Each Voyagers' cosmic ray detector, magnetometer,
plasma wave detector and low-energy charged particle detector
all still operational. In addition, the Ultraviolet Spectrometer
on Voyager 1 and the Plasma Science instrument on Voyager
2 continue to return data. Both spacecraft are expected to
continue to operate and send back valuable data until at least
the year 2020.
Credit Astronomy: Roen Kelly
mission currently employs the equivalent of about 10 full-time
people at JPL, significantly less than the approximately 300
during the height of its famed "Grand Tour" of the
planets through 1989. Only two veterans of the Voyager launches
still work on the flight team. Some of the summer interns
the team has employed were not even born when the spacecraft
were launched. The project scientist, Dr. Ed Stone of the
California Institute of Technology has been with the mission
since inception and two original principal investigators -
Dr. Stamatios Krimigis of the Applied Physics Laboratory and
Dr. Norman Ness of the University of Delaware - remain.
the journey, the Voyagers flew by Jupiter, Saturn, Uranus
and Neptune and returned nearly 80 thousand images and more
than 5 trillion bits of data. After traveling through space
for more than 27 years, Voyager 1 is now more than 14 billion
kilometers (94 AU) from the Sun, heading in a northerly direction
toward interstellar space. Voyager 2, closer at about 11 billion
kilometers (75 AU), is headed on a southerly path toward interstellar
space. Voyager 1 is now the furthest human-made object from
the Sun, having surpassed Pioneer 10 on February 17, 1998.
the beginning of the Interstellar Mission in 1990, the two
spacecraft have returned well more than 65 billion bits of
data, though at lower data rates than during the Grand Tour.
The data continue to reveal new characteristics of the effects
of the sun in the distant solar wind. As an example, a Coronal
Mass Ejection (CME) shock wave from the October 2003 solar
storms was detected at Voyager 2 in mid-April 2004. Some of
the most powerful flares in recorded history hurled billion-ton
clouds of gas, called coronal mass ejections (CMEs), into
the solar system. By the time the resulting shocks reached
Voyager 2, about 6 months later, they had combined into Merged
Interaction Regions and had slowed considerably. Traveling
at 600 km/sec, it had slowed considerably from the 1500-2000
km/sec detected last Fall as the storms left the Sun. Voyager
2 measured the speed of the shock, its composition, temperature
and magnetism. When combined with measurements from SOHO,
Mars Odyssey, Ulysses, Cassini and other spacecraft, the Voyager
data show how far-ranging CMEs evolve and dissipate.
the past two years or so, Voyager 1 has detected phenomena
unlike any encountered before in all its years of exploration.
These observations and what they may infer about the approach
to the termination shock have been the subject of on-going
scientific debates. While some of the scientist believed that
the passage past the termination shock had already begun,
some of the phenomena observed were not what would have been
expected. So the debate continues while even more data are
being returned and analyzed. However, it is certain that the
spacecraft are in a new regime of space. The observed plasma
wave oscillations and increased energetic particle activity
may only be the long-awaited precursor to the termination
shock. If we have indeed encountered the termination shock,
Voyager 1 would be the first spacecraft to enter the solar
system's final frontier, a vast expanse where wind from the
Sun blows hot against thin gas between the stars: interstellar