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Posted: 04 Aug 2014 05:28 AM
PDT
A demonstration that in space
as on Earth solar power is an alternative to dangerous nuclear power is to
come this week when a solar-powered spacecraft called Rosetta will rendezvous
with a comet at 375 million miles from the Sun.
The Rosetta space probe,
energized with solar power, is to meet up Wednesday with Comet
67P/Churyumov-Gerasimenko. It will begin making observations, relaying back
to Earth high-resolution images and information from its sensors, of the
two-and-a-half mile wide comet Rosetta will subsequently send a lander down
to the comet that will drill into it and perform a variety of experiments.
For a year, Rosetta will fly alongside the comet, named after the two
Ukranian astronomers who discovered it in 1969.
For decades, the United States
and the Soviet Union, and now Russia, stressed the use of atomic energy as a
source of power in space—and there have been accidents as a result.
The most serious were the falls
back to Earth of a U.S. satellite with a SNAP-9A plutonium-238 radioisotope
thermal generator on board in 1964, disintegrating as it fell, dispersing
plutonium worldwide, and of the Soviet Cosmos Satellite 954 in 1978, with an
atomic reactor on board, also breaking up, and spreading nuclear debris for
hundreds of miles across the Northwest Territories of Canada.
The late Dr. John Gofman,
professor of medical physics at the University of California at Berkeley,
long connected the SNAP-9A accident and its dispersal of plutonium with a
global increase in lung cancer. Canada demanded compensation for the
Cosmos-954 accident which the Soviet Union eventually paid, in part.
Now all satellites are
solar-powered as is the International Space Station. But there has been a
push to continue to use nuclear power on space probes with NASA and formerly
Soviet and now Russian space authorities insisting that solar power cannot be
harvested far from the Sun.
However, the European Space
Agency declares on its website—
—“The solar cells in Rosetta’s
solar panels are based on a completely new technology, so-called
Low-intensity Low Temperature Cells. Thanks to them, Rosetta is the first
space mission to journey beyond the main asteroid belt relying solely on
solar cells for power generation. Previous deep-space missions used nuclear
RTGs, radioisotope thermal generators. The new solar cells allow Rosetta to
operate over 800 million kilometres from the Sun, where levels of sunlight
are only 4% those on Earth. The technology will be available for future
deep-space, such as ESA’s upcoming Jupiter Icy Moons Explorer.”
ESA notes: “ESA has not
developed RTG i.e. nuclear technology, so the agency decided to develop solar
cells that could fill the same function.”
Rosetta, launched in 2004,
“relies entirely on the energy provided by its innovative solar panels for
all onboard instruments and subsystems,” says ESA.
NASA has begun to follow ESA’s
lead. It went with solar power for its Juno mission to Jupiter that is
now underway. Launched in 2011, energized by solar power, the Juno space
probe is to arrive at Jupiter in 2016.
At the distance at which
Rosetta will encounter Comet 67P/Churyumov-Gerasimenko or at which Juno will
be doing experiments involving Jupiter or ESA’s Jupiter Icy Moons Explorer
will work, energy from the Sun is but a small fraction of what it is on
Earth. Still, it can be effectively utilized. (NASA’s last space probe
mission to Jupiter, Galileo, launched in 1989, was plutonium-powered and NASA
officials insisted, including in sworn testimony countering a challenge to
Galileo in federal court, that this was the only energy choice. There were numerous
protests against Galileo and have been to subsequent nuclear space shots led
by the Global Network Against Weapons & Nuclear Power in Space (www.space4peace.org).
Rosetta is named after the
Rosetta Stone, a slab of basalt found in Egypt in 1799 with inscriptions
carved on it that enabled the deciphering of hieroglyphics, the ancient
language of Egypt. “As a result of this breakthrough, scholars were able to
piece together the history of a lost culture,” notes ESA.
Likewise, “Rosetta’s prime
objective is to help understand the origin and evolution of the Solar
System,” says ESA. “The comet’s composition reflects the composition of the
pre-solar nebula out of which the Sun and the planets of the Solar System formed,
more than 4.6 billion years ago. Therefore, an in-depth analysis of Comet
67P/Churyumov-Gerasimenko by Rosetta and its lander will provide essential
information to understand how the Solar System formed.”
ESA adds, “There is convincing
evidence that comets played a key role in the evolution of the planets,
because cometary impacts are known to have been much more common in the early
Solar System than today. Comets, for example, probably brought much of the
water in today’s ocean. They could even have provided the complex organic
molecules that may have played a crucial role in the evolution of life on
Earth.”
Rosetta “will be undertaking
several ‘firsts’ in space exploration,” says ESA. “It will be the first
mission to orbit and land on a comet.” And, Rosetta will be “the first
spacecraft to witness, at close proximity” the changes in a comet as it
approaches the Sun. Rosetta’s lander “will obtain the first images from a
comet’s surface and make the first in-situ subsurface analysis of its
composition.”
The Rosetta lander, given the
name Philea, is to touch down on the comet’s surface in November and “remain
operational through the end of 2015….A drilling system will obtain samples
down to 23 cm below the surface and will feed these to the spectrometers for
analysis, such as to determine the chemical composition. Other instruments
will measure properties such as near-surface strength, density, texture,
porosity, ice phases and thermal properties…In addition, instruments on the
lander will study how the comet changes during the day-night cycle, and while
it approaches the Sun.”
The lander is being called
Philea for Philea Island in the Nile where an obelisk was found that
supplemented the use of the Rosetta Stone in the deciphering of
hieroglyphics.
The cost of the mission is 1.3
billion Euros ($1.75 billion at current exchange rates) and ESA asks the
question: “Why spend such a huge amount of public money on studying remote
stones in space?”
ESA responds: “ESA’s task is to
explore the unknown. In the case of Rosetta, scientists will be learning
about comets, objects that have fascinated mankind for millennia” and “are
thought to be the most primitive objects in the Solar System, the building
blocks from which the planets were made. So Rosetta will provide exciting new
insights into how the planets, including Earth, were born and how life
began.”
There can be things that can
still go wrong on the mission. Gases from the comet could affect Rosetta
flying with it. Philae could fail to get hooked to the comet, although a
“harpoon” system has been devised for it to anchor itself to the comet’s
surface.
But if the Rosetta mission is a
success it will be a superb example of a space mission that represents no
nuclear threat to life on Earth and of a quest with the highest of
purposes—exploring the mysteries of the Solar System and the origins of life.
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nuclear power in space appeared first on Enformable.
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