Pipe organ’ plays above the Sun
By Paul Rincon
Immense coils of hot, electrified gas in the Sun’s atmosphere behave like a musical instrument, scientists say. These “coronal loops” carry acoustic waves in much the same way that sound is carried through a pipe organ. Solar explosions called micro-flares generate sound booms which are then propagated along the coronal loops. “The effect is much like plucking a guitar string,” Professor Robert von Fay-Siebenbuergen told BBC News at the National Astronomy Meeting in Preston. The corona is an atmosphere of hot, electrically-charged gas – or plasma – that surrounds the Sun. The temperature of the corona should drop the further one moves from the Sun. But, in fact, the coronal temperature is up to 300 times hotter than the Sun’s visible surface, or photosphere. And no one can explain why.
The coronal loops arch hundreds of thousands of kilometres above the Sun’s surface like huge fiery fountains, and are generated by the Sun’s magnetic field. As solar plasma travels from the photosphere into the loops, it is heated from about 6,000 Kelvin (5,700C) to upwards of one million Kelvin. Solar explosions called micro-flares can release energy equivalent to millions of hydrogen bombs. These blasts can send immensely powerful acoustic waves hurtling through the loops at tens of kilometres per second, creating cosmic “organ music”. “These loops can be up to 100 million kilometres long and guide waves and oscillations in a similar way to a pipe organ,” said Dr Youra Taroyan, from the Solar Physics and Space Plasma Research Centre (SP2RC) at the University of Sheffield. The sound booms decay in less than an hour and dissipate in the very hot solar corona. Professor von Fay-Siebenbuergen, who is director of SP2RC, said that studying how plasma was heated to such high temperatures in coronal loops could speed up the technological development of industrial-scale nuclear fusion on Earth.
‘Star on Earth’
Nuclear fusion is the same process which powers the Sun and other stars. Unlike the burning of fossil fuels, fusion reactions produce no carbon dioxide, the greenhouse gas blamed by scientists for warming the planet. Fusion works on the principle that energy can be released by forcing together atomic nuclei rather than by splitting them, as in the case of the fission reactions that drive existing nuclear power stations. In the core of the Sun, huge gravitational pressure allows this to happen at temperatures of around 10 million Celsius. At the much lower pressure that is possible on Earth, temperatures to produce fusion need to be much higher – above 100 million Celsius In nuclear fusion experiments, powerful magnetic fields can be used to isolate hot plasma from the walls of a containment vessel. This reduces the conductive heat loss, allowing the electrified gas to be heated to high temperatures. The most promising magnetic confinement systems are ring-shaped – a torus. Professor von Fay-Siebenbuergen said a coronal loop could give clues to improving nuclear fusion because it could be regarded as a half-torus.
Prof Róbert von Fáy-Siebenbürgen
email: Robertus [at] sheffield [dot] ac [dot] uk
“My main research interests lie in the general field of space plasma
physics. The heating processes that generate and sustain the observed
high temperature of the solar and stellar atmospheres have so far
defied a quantitative understanding despite the multitude of efforts
spanning over half a century. The aim of my research is to address
these questions through theoretical (both numerical and exact
analytical methods) and observational studies (joint ground-based and
satellite missions). Particular attention is paid to the solar
influence on the magnetosphere and space weather.
Understanding the subtleties of plasma confinement at high
temperatures is also strongly linked to modern fusion physics. My
interdisciplinary research (including e.g. magnetohydrodynamics [MHD],
computational fluid dynamics [CFD], kinetic theory) has direct
applications in the new and rapidly emerging discipline of
helioseismology and space weather. I became Head of the Solar Physics
& Upper-Atmosphere Research Group (SPARG) in the Department of Applied
Mathematics in 2004.”
My current projects in SPARG include:
* Solar Physics
* Space Weather/Space Plasma Physics
* Computational Magnetohydrodynamics (CMHD)
* Stability of MHD shear flows
“Have you ever wondered,” the Stanford-Lockheed Institute for Space
Research asks, “what the Sun would sound like if you could hear it?”
Luckily, you can now listen to “sun sounds,” courtesy of the SOHO
Michelson Doppler Imager (MDI) project, “part of an international
collaboration to study the interior structure and dynamics of the Sun”
– including what the sun sounds like.
As you probably know, “the Sun is essentially spherical” – but this
also means that it “forms a spherical acoustical resonator with
millions of different normal modes of oscillation. Due to the waves’
long life times, destructive interference filters out all but the
resonant frequencies, transforming the random convective noise into a
very rich line spectrum in the five-minute range. Thus, convection
acts rather like a random clapper causing the Sun to ring like a
To measure these oscillations – indeed, to listen to the sun
“ring[ing] like a bell” – a whole new kind of densely connected,
architectural network is required: “an uneclipsed instrument in space,
observatories at the Earth’s poles, and a network of observatories
around the Earth.”
All of these, of course, would need unimpeded sonic access to the
The sun can be listened to indirectly, of course, in the form of solar
storms interfering with terrestrial radio and television broadcasts –
which brings to mind the story of how radio astronomy was first
discovered, at Bell Labs in New Jersey. Thinking that his antenna was
generating its own heat and noise, and therefore interfering with the
experiment at hand (which I believe had something to do with
telephones: discovering the universe by telephone), Karl Jansky
eventually realized that all that white noise was *coming from deep
space* – it was the sound of stars – and that he had discovered the
radio-noise background in which our entire universe hums, eternally,
at every second of every day, a kind of quiet hiss or whisper that we
now know is an omnipresent sonic fossil left over from the Big Bang.
Space is full of sounds.
It was reported by Reuters, for instance, almost exactly two years
ago, that a “particularly monstrous black hole has probably been
humming B-flat for billions of years, but at a pitch no human could
hear, let alone sing” – and that scientists “believe it is the deepest
note ever detected in the universe.”
“As the black hole pulls material in, [Andrew Fabian of the Institute
of Astronomy at Cambridge, England] said, it also creates jets of
material shooting out above and below it, and it is these powerful
jets that create the pressure that creates the sound waves.”
Seismology in B-flat.
Or – similarly, about two years ago – the consistently exciting
magazine New Scientist revealed that the Big Bang sounded “rather like
a large jet plane flying 100 feet above your house in the middle of
the night”: “Giant sound waves propagated through the blazing hot
matter that filled the Universe shortly after the Big Bang. These
squeezed and stretched matter, heating the compressed regions and
cooling the rarefied ones. Even though the Universe has been expanding
and cooling ever since, the sound waves have left their imprint as
temperature variations on the afterglow of the big bang fireball, the
so-called cosmic microwave background.”
Enter Karl Jansky and his broken telephone, throw in some
helioseismology – and you get landscapes of noise, in deep space.
(For some gorgeous MP3s of global shortwave radio music, full of radio
hiss and strange sidereal cross-broadcasts – the sun whispering to
itself, drenched in light – see the blog ShortWaveMusic; and for
another post on a similar theme, see Radio Haloes of Earth).
NOW IN 3-D
A satellite duo called STEREO has produced the first ever three-
dimensional images of the Sun, NASA announced on Monday.
Scientists hope the images of the Sun’s outer atmosphere, or corona,
will help improve their computer models of solar activity. Better
predictions could help engineers protect the sensitive electronics on
satellites from the ravages of solar storms.
The two STEREO (Solar Terrestrial Relations Observatory) spacecraft,
which launched into space in October 2006, are able to make the 3D
images by taking simultaneous pictures as one flies front of Earth and
the other flies behind it in the planet’s orbit around the Sun.
Among the new observations are ultraviolet images showing holes in the
scorchingly hot corona; the holes appear dark in part because they
contain fewer particles that emit light. A 3D video shows the coronal
holes rotating around the Sun (learn how to make your own 3D glasses
to get the full effect). The solar wind – a stream of charged
particles from the Sun that flows throughout the solar system –
emanates from these holes.
STEREO also captured an active region on the Sun. Magnetic loops in
this stormy region are visible in this 3D video. It is when these
loops get twisted that the Sun can unleash a torrent of radiation that
can be hazardous to spacecraft or astronauts.
New vantage point
Before the STEREO mission, images of the Sun were taken from only one
vantage point – an imaginary line drawn from Earth to the Sun. For
instance, the prolific Solar and Heliospheric Observatory (SOHO)
spacecraft orbits the Sun at a point on this line where the gravity of
the Sun and Earth are balanced.
“We have to move away from the traditional Sun-Earth line . . . to
really get a deeper understanding of what’s inside the Sun [and] how
is it affecting the entire solar system we live in,” says NASA’s
STEREO programme scientist Madhulika Guhathakurta.
That is not the only way in which STEREO is an improvement over its
predecessors. SOHO can study solar eruptions stretching just a short
distance from the Sun – only 15% of the distance from the Sun to
STEREO can observe these eruptions as they travel all the way from the
Sun to the Earth (see Advancing solar blasts filmed for the first
time). “To cover the vast distance from the 15% that we viewed to the
85% that we didn’t, scientists were modelling in the dark,”
The new images were taken during a quiet period in the Sun’s 11-year
cycle of activity, when there is an eruption of particles and
radiation from the Sun about once every other day. By contrast, there
can be five or more storms per day at solar maximum.
“It’s much better if we can have clean events, where we see there’s
only one active region in the Sun’s centre,” says team member Spiro
Antiochos of the US Naval Research Laboratory in Washington, DC, US.
“This one active region puts out one nice, well-shaped solar storm,
which comes right at us where STEREO takes pictures. Then we can see
how well (the) models do, to the point where we can handle the more
complicated regions,” he says.
SOLAR TOWER IS COOL BUT
SOLAR POWER FROM ORBIT
Solar Power From Space: A Better Strategy for America and the World?
By Al Globus / 17 May 2007
Suppose I told you that we could build an energy source that:
* unlike oil, does not generate profits used to support Al Qaeda
and dictatorial regimes.
* unlike nuclear, does not provide cover for rogue nations to hide
development of nuclear weapons.
* unlike terrestrial solar and wind, is available 24/7 in huge
* unlike oil, gas, ethanol and coal, does not emit greenhouse
gasses, warming our planet and causing severe problems.
* unlike nuclear, does not provide tremendous opportunities for
* unlike coal and nuclear, does not require ripping up the Earth.
* unlike oil, does not lead us to send hundreds of thousands of
our finest men and women to war and spend hundreds of billions of
dollars a year on a military presence in the Persian Gulf.
The basic idea: build huge satellites in Earth orbit to gather
sunlight, convert it to electricity, and beam the energy to Earth
using microwaves. We know we can do it, most satellites are powered by
solar energy today and microwave beaming of energy has been
demonstrated with very high efficiency. We’re talking about SSP –
solar satellite power.
SSP is environmentally friendly in the extreme. The microwave beams
will heat the atmosphere slightly and the frequency must be chosen to
avoid cooking birds, but SSP has no emissions of any kind, and that’s
not all. Even terrestrial solar and wind require mining all their
materials on Earth, not so SSP. The satellites can be built from lunar
materials so only the materials for the receiving antennas (rectennas)
need be mined on Earth. SSP is probably the most environmentally
benign possible large-scale energy source for Earth, there is far more
than enough for everyone, and the sun’s energy will last for billions
While help is always nice, the U.S. can build and operate SSP alone,
and SSP is nearly useless to terrorists. The satellites themselves are
too far away to attack, the rectennas are simple, solid metal
structures, and there is no radioactive or explosive fuel of any kind.
Access to SSP energy cannot be cut by foreign governments, so America
will have no need to maintain an expensive military presence in oil-
The catch is cost. Compared to ground based energy, SSP requires
enormous up-front expense, although after development of a largely-
automated system to build solar power satellites from lunar materials
SSP should be quite inexpensive. To get there, however, will cost
hundreds of billions of dollars in R&D and infrastructure development
– just what America is good at. And you know something, we’re spending
that kind of money, not to mention blood, on America’s Persian Gulf
military presence today, and gas went over $3/gallon anyway. In
addition, we may end up spending even more to deal with global
warming, at least in the worst-case scenarios. Expensive as it is, SSP
may be the best bargain we’ve ever had.
What should we do? Besides having NASA do interesting and inspiring
things, direct and fund NASA to do something vital: end U.S.
dependence on foreign oil by developing SSP. Redirect the lunar base
to do the mining, and develop the launch vehicles, inter-orbit
transfer, and space manufacturing capacity to end oil’s energy
dominance completely and forever. It will be expensive, but it’s a
better, cheaper, safer strategy than military control of oil in far
Oh, by the way, SSP will develop lunar mining, launch vehicles, and
large satellite construction – most of what we need to build space
Al Globus serves on the National Space Society Board of Directors and
is a senior research associate for Human Factors Research and
Technology at San Jose State University at NASA Ames Research Center.
* Power of the Future: 10 Ways to Run the 21st Century
* Pentagon Considering Study on Space-Based Solar Power
* Orbital Outposts: A Better Bet than a Moonbase?
NOTE: The views of this article are the author’s and do not reflect
the policies of the National Space Society.
Pentagon Considering Study on Space-Based Solar Power
By Jeremy Singer / 11 April 2007
The Pentagon’s National Security Space Office (NSSO) may begin a study
in the near future on the possibility of using satellites to collect
solar energy for use on Earth, according to Defense Department
The officials said the study does not mean that the military plans to
demonstrate or deploy a space-based solar power constellation.
However, as the Pentagon looks at a variety of alternative energy
sources, this could be one possible method of supplying energy to
troops in bases or on the battlefield, they said.
The military’s work in this area also could aid development of a
system that could provide energy to non-military users as well,
according to Lt. Col. Michael Hornitschek, chief of rated force policy
on the Air Force staff at the Pentagon.
Hornitschek, who has been exploring the concept of space-based solar
power in his spare time, recently briefed the NSSO on the concept of
space-based solar power, and stimulated interest in conducting a
formal study, according to Lt. Col. M.V. “Coyote” Smith, chief of
future concepts at the NSSO. The NSSO would need to find the financial
resources and available manpower to conduct the study, Smith said.
Hornitschek would lead work on the study on behalf of the NSSO if the
NSSO elects to pursue it, and he said he hopes that a system could be
deployed in roughly 20 years.
John Mankins, president of the Space Solar Power Association in
Washington, said space-based solar power could offer a massive
improvement over terrestrial solar collection devices because constant
exposure to the sun avoids the nighttime periods where terrestrial
systems cannot collect solar energy.
The ability to constantly gather solar energy would allow a space-
based system to avoid safety concerns to other satellites or people on
the ground by constantly transmitting energy to Earth at a level that
is high enough to be useful but low enough so as not to cause any
damage, said Mankins, a former NASA official who previously served as
manager of advanced concept studies at NASA headquarters before
leaving the agency in 2005.
Jeff Kueter, president of the Marshall Institute, a Washington think
tank, said it is too early to determine if space-based solar power is
viable, but said that if the concept is successful, it could be a
potential “game changer” for energy use.
The concept could find broad bipartisan support as it could meet the
desires both of conservatives seeking to end dependence on foreign
energy sources, as well as liberals who are looking for an
environmentally friendly source of energy, Kueter said.
While space-based solar power may sound like a high-risk proposal, it
is worth investing several million dollars in the near term to study
the concept because of the potential high payoff, Kueter said. If the
studies indicated that the concept might be feasible, it would be
worthwhile for the Pentagon to conduct flight demonstrations to prove
out the technology in space, he said.
If the Pentagon chose to pursue flight demonstrations or deployment of
a space-based solar power system, it could share costs by partnering
with NASA, the Department of Energy and other government agencies,
The concept of space-based solar power might appear to threaten
traditional energy industries, Kueter said. However, the rapidly
increasing demands for energy and diminishing supply of natural
resources means that traditional energy companies may need to find new
ways of doing business in the future, and they could likely find a way
to be a part of the space-based solar power effort through ways like
contributing expertise in areas like energy distribution, he said.
The NSSO would likely ask experts from industries like electrical
power to be involved in the study if it chooses to conduct it to draw
on their experience with power distribution, Smith said.
If the NSSO initiates the study on space-based solar power, it would
likely be the first time that the Pentagon has looked at the concept,
Smith said he hoped the study could create a repository of information
about space-based solar power that may have been conducted by other
agencies, as well as any that may have existed within the military.
Hornitschek said it is too early to estimate the likely constellation
size, types of orbits or cost of a space-based solar-power
constellation. However, the satellites would likely feature very
large, powerful solar arrays. In addition, the cost of launching a
constellation of such large satellites with the types of launch
vehicles available today would be a challenge, Hornitschek said.
Mankins said a large constellation could demonstrate a significant
launch opportunity to industry, and could provide the stimulus needed
for industry to bring reusable launch concepts to fruition.