Spaceflight Now +
Premium video content for our Spaceflight Now Plus subscribers.
Delta rocket lofts GPS
The Boeing Delta 2 rocket lifts off Saturday morning with the GPS 2R-13 satellite from pad 17B at Cape Canaveral, Florida.
Launch in full
This longer-length clip follows the Delta 2 rocket during its late-night ascent carrying the latest Global Positioning System satellite. (2min 25sec file)
A red alarm triggers Friday morning's countdown to launch of Boeing's Delta 2 rocket carrying a GPS satellite to be scrubbed at Cape Canaveral, Florida. (1min 52sec file)
Mission scientists preview NASA's Swift gamma-ray burst detection satellite being readied for launch into Earth orbit. (39min 49sec file)
Voting from space
International Space Station Expedition 10 commander Leroy Chiao talks about the election and voting from orbit with CNN's Paula Zahn. (10min 20sec file)
Delta 4-Heavy preview
Preview what a Boeing Delta 4 rocket launch will be like with this animation package of a "Heavy" configuration vehicle. (1min 41sec file)
Cassini science update
Radar imagery of Saturn's moon Titan and other new data from the Cassini spacecraft is presented during this JPL news conference on Thursday. (54min 48sec file)
Scientists and mission officials discuss the initial pictures and data obtained during Cassini's flyby of Titan during this JPL news conference on Wednesday. (55min 18sec file)
The first pictures taken by Cassini during this close encounter with Titan are received at the Jet Propulsion Laboratory to the delight of the mission's imaging leader. (2min 21sec file)
Become a subscriber
Origin of cosmic rays revealed with gamma rays
PARTICLE PHYSICS AND ASTRONOMY RESEARCH COUNCIL RELEASE
Posted: November 7, 2004
A team of UK astronomers working with international partners has produced the first ever image of an astronomical object using high energy gamma rays, helping to solve a 100 year old mystery - an origin of cosmic rays. Their research, published in the journal
Nature on November 4th, was carried out using the High Energy
Stereoscopic System (H.E.S.S.), an array of four telescopes, in
Namibia, South-West Africa.
The astronomers studied the remnant of a supernova that exploded
some 1,000 years ago, leaving behind an expanding shell of debris
which, seen from the Earth, is twice the diameter of the Moon. The
resulting image helps to solve a mystery that has been puzzling
scientists for almost 100 years - the origin of cosmic rays.
Cosmic rays are extremely energetic particles that continually
bombard the Earth, thousands of them passing through our bodies
every day. The production of gamma rays in this supernova shock
wave tells us that it is acting like a giant particle accelerator
in space, and thus a likely source of the cosmic rays in our
Dr Paula Chadwick of the University of Durham said "This picture
really is a big step forward for gamma-ray astronomy and the
supernova remnant is a fascinating object. If you had gamma-ray
eyes and were in the Southern Hemisphere, you could see a large,
brightly glowing ring in the sky every night."
Professor Ian Halliday, CEO of PPARC which funds UK participation
in H.E.S.S. said "These results provide the first unequivocal
proof that supernovae are capable of producing large quantities
of galactic cosmic rays - something we have long suspected, but
never been able to confirm."
Gamma rays are the most penetrating form of radiation we know,
around a billion times more energetic than the X-rays produced
by a hospital X-ray machine. This makes it very difficult to use
them to create an image - they just pass straight through any
surface which we might use to reflect them, for instance.
However, luckily for life on Earth, gamma rays from objects in
outer space are stopped by the atmosphere; when this happens, a
faint flash of blue light is produced, lasting for a few
billionths of a second. The astronomers used images of these
flashes of light, called Cherenkov radiation, to make a gamma
ray 'image' for the first time.
The H.E.S.S. collaboration
The High Energy Stereoscopic System (H.E.S.S.) team consists of
scientists from Germany, France, the UK, the Czech Republic,
Ireland, Armenia, South Africa and Namibia.
The H.E.S.S. array
Over the last few years, the H.E.S.S. collaboration have been
building a system of four telescopes in the Khomas Highland
region of Namibia, to study very-high-energy gamma rays from
cosmic particle accelerators. The telescopes, known as
Cherenkov telescopes, image the light created when high-energy
cosmic gamma rays are absorbed in the atmosphere, and have
opened a new energy domain for astronomy. The H.E.S.S.
telescopes each feature mirrors of area 107 square metres,
and are equipped with highly sensitive and very fast 960-pixel
light detectors in the focal planes. Construction of the
telescope system started in 2001; the fourth telescope was
commissioned in December 2003. Observations were being
made even while the system was being built, first using a single
telescope, then with two and three telescopes. While only the
complete four-telescope system provides the full performance,
the first H.E.S.S. telescope alone was already superior to any
of the instruments operated previously in the southern
hemisphere. Among the first targets to be observed with a two-
telescope instrument was the Galactic Centre.