82 AUSTRALIAN SKY & TELESCOPE July 2019
FOCAL POINT by John SarkissianO
n November 5, 2018,
NASA’s Voyager 2 spacecraft
crossed the heliopause and
entered interstellar space. It was the
culmination of a remarkable voyage of
discovery and exploration that began
decades earlier and which inspired one
budding astronomer.
As a school boy, the first astronomy
book I ever owned was Patrick Moore’s
Challenge of the Stars. Beautifully
illustrated by David A. Hardy, it
captured my 10-year-old imagination
like no other book. One chapter
described a future mission to the
outer planets, dubbed the Grand
Tour. It involved two spacecraft to be
launched in the late 1970s that would
take advantage of a once-in-a-lifetime
alignment of the planets, which would
enable the spacecraft to swing by
each of the outer planets by using the
concept of gravity assist. I couldn’t wait
for those missions to launch. So you
can imagine my delight when just a few
years later, in the very week that Elvis
Presley passed away, the first of the twin
spacecraft, Voyager 2, began its journey.
Two years later, the twin Voyagers
passed by Jupiter, revealing the planetin spectacular detail. Colour pictures
of the swirling Great Red Spot, the
Galilean moons and the volcanoes of
Io, were plastered on the walls of my
physics classroom and in my bedroom
at home. They were inspiring sights.
As the years passed, Voyager 2 in turn
flew by Saturn, Uranus and Neptune,
returning amazing vistas. With each
encounter I would check Challenge of
the Stars to see how accurate Moore’s
predictions had been. He was doing
pretty well.
For the Uranus and Neptune
encounters in the 1980s, the Parkes
telescope was linked with the
antennas at NASA’s tracking station at
Tidbinbilla, near Canberra, to increase
the signal strength and return even
more data than would otherwise have
been possible. Like almost everyone else,
I was a spectator then, amazed that I
was living in such privileged times.
In the very year that Voyager 2 was
launched, the cover of my year nine
mathematics text book featured a
painting of the CSIRO Parkes telescope.
I would often sit in class and stare at
the painting, daydreaming of working
there one day. And decades later, Idid indeed find myself working at the
Observatory, as an Operations Scientist.
It came to pass that, in early October
2018, we received word from NASA
and the Jet Propulsion Laboratory that
they were interested in having Parkes
track Voyager 2 again, as all indications
showed that it was fast approaching
the heliopause — the place where the
solar wind peters out. Normally, the
antennas at Tidbinbilla were sufficient
to track Voyager 2, but as fate would
have it, several high-profile missions
were nearing their critical phases and
required near constant support by
the antennas of NASA’s Deep Space
Network; they were not available to
track Voyager 2. The Parkes telescope
was the only other radio antenna in
the Southern Hemisphere that could
see Voyager 2, and which was sensitive
enough to receive the feeble signals.
The CSIRO agreed to support the
mission once again. But time was short
and a crash program was started to have
the telescope ready in time. The initial
testing and setup began on November 1
and four days later, Voyager 2 crossed the
heliopause. We had made it just in time.
For the next four months, we continued
tracking the spacecraft as it ventured
further into interstellar space, returning
high-quality data on the nature of that
distant environment.
Throughout the tracking, I marvelled
at how the Voyager 2 probe had survived
for so long. Launched more than 40
years earlier, its journey had mirrored
my own. But I wasn’t alone. Patrick
Moore had written a book describing the
beauty and grandeur of astronomy as
exploration. By revealing the immensity
and grandeur of our Solar System, the
Voyager missions had inspired an entire
generation of school children, just like
me. It really was a Grand Tour.■ JOHN SARKISSIAN is Operations
Scientist at the CSIRO Parkes Radio
Observatory, where his main responsibilities
are the operation of and systems
development for the radio telescope,
and remote for support and training of
astronomers with their observations.Voyager 2 has passed
the heliopause, the
boundary between the
bubble blown by the
Sun’s solar wind and
interstellar space.N A S A /J P L- C A LT E C HVoyager 2:
A personal voyage
A child’s dream of the stars has paralleled that of NASA’s
longest-running space mission.