Thread: GLAST Satellite to Reveal Unseen Universe

This thing is launching next month:



It will be detecting, for the first time, very high energy gamma rays at the extreme end of the electromagnetic spectrum that can only be emitted by extreme processes, perhaps even dark matter annihilating itself. By observing the cosmos, it will help explain the existence of new particles.

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It will also compare the speeds of high energy gamma rays, the more energetic of which might be slowed by sensitivity to the extremely small scale of a fabric of spacetime boiling with multidimensional "strings." This might bolster the existence of strings and string theory, the most successful attempt thus far to join quantum mechanics (on the sub-atomic scale) to gravity (on a cosmic scale).

It will also reveal a completely hidden universe, a night sky lit up with jets from super-massive black holes that lurk at the center of galaxies



with radii wider than the orbit of Mars containing billions of solar masses, that might themselves eventually evaporate and collapse, leaving hitherto unseen gamma traces.




Found a decent explanation from a German website:

Gamma radiation, the most energetic form of radiation in the electromagnetic spectrum, is invisible to the human eye. Among the entire electromagnetic spectrum, only the narrow band of optical wavelengths (to say: visible light) is directly accessible by the human eye. In order to observe gamma rays, one needs to develop and apply dedicated detector techniques, similarily as necessary to access other wavebands invisible for the human eye like radio waves, infrared and ultraviolett radiation and X-rays. Because the physical generation processes of electromagnetic radiation at other wavelengths are different, also the detection principles differ with the energy of the radiation.




What are the scientific goals of the GLAST mission?



Because high energy gamma radiation could only be produced unter extreme conditions, GLAST will study the most energetic astromonical objects in the Universe. In the energy range of GLAST, the Universe is largely transparent to gamma rays. This way especially energetic sources near the edge of the visible Universe can be investigated. There is good reason to expect that GLAST will see known classes of sources deep of the early universe. Gamma rays point back to their sources, unlike cosmic rays, which are deflected by magnetic fields. GLAST will study such exotic objects like heavy black holes and neutron stars, but will also investigate the life cycle of stars, and trace the dark components of matter. But also our own Galaxy, the Milky Way, is a source of gamma radiation, which is generated by interactions of energetic particles of the cosmic radiation and interstellar matter. And even our Sun generate gamma rays at its surface during flare outbursts . And with the capabilities of the GLAST instrument there is a good chance given for unexpected and perhaps even more fascinating discoveries!

Even more Astrophysics with GLAST ?

Why GLAST has be a satellite experiment?

There are a few hurtles astronomers must over come in order to detect gamma rays. For one, there are not a lot of gamma rays out there to be detected. Scientists must be able to wait a long time to get enough information from a source. Another is the fact that most gamma rays are absorbed by the Earth's atmosphere. This is good since gamma rays are extremely energetic and harmful to life on Earth, but if you want to observe gamma-ray sources from the Universe it can pose a problem. Therefore gamma-ray observations are generally done with high-altitude balloons or satellites launched into space, above the atmosphere.

From Nasa:

"WHAT DOES GLAST" STAND FOR?

Gamma-ray Large Area Space Telescope

WHAT IS THE PURPOSE OF THE GLAST MISSION?

The Universe is home to numerous exotic and beautiful phenomena, some of which can generate inconceivable amounts of energy. GLAST will open this high-energy world. Astronomers will have a superior tool to study how black holes, notorious for pulling matter in, can accelerate jets of gas outward at fantastic speeds. Physicists will be able to search for signals of new fundamental processes that are inaccessible in ground-based accelerators and observatories.

WHAT ARE GLAST'S MAIN MISSION OBJECTIVES?

• To understand the mechanisms of particle acceleration in active galactic nuclei (AGNs), neutron stars, and supernova remnants (SNRs).
• Resolve the gamma-ray sky: characterize unidentified sources and diffuse emission.
• Determine the high-energy behavior of gamma-ray bursts (GRBs) and variable sources.
• Probe dark matter and the early Universe.

WHAT KINDS OF THINGS WILL GLAST STUDY?

1. Blazars and Active Galaxies + Learn more

2. Gamma-ray Bursts + Learn more




3. Neutron Stars + Learn more




4. Cosmic Rays and Supernova Remnants + Learn more





5. Milky Way Galaxy + Learn more




6. The Gamma-ray Background + Learn more



7. The Early Universe + Learn more
8. Solar System: Sun, Moon, and Earth + Learn more
10. Dark Matter + Learn more
11. Testing Fundamental Physics + Learn more
12. Unidentified Sources and the Unknown + Learn more

WHAT'S NEW AND REVOLUTIONARY ABOUT THIS MISSION?

GLAST is the first imaging gamma-ray observatory to survey the entire sky every day and with high sensitivity. It will give scientists a unique opportunity to learn about the ever-changing Universe at extreme energies. GLAST will detect thousands of gamma-ray sources, most of which will be supermassive black holes in the cores of distant galaxies. GLAST uses Einstein's principle of E = mc 2 to convert gamma rays into matter in order to track their cosmic origins. GLAST observations may reveal signatures of new physics, including the potential to identify the unknown particle which may compose dark matter.

WHAT ARE SOME OF THE QUESTIONS GLAST HOPES TO ANSWER?

How do black holes accelerate jets of material to nearly light speed? What is the mysterious dark matter? What mechanism produces the stupendously powerful explosions known as gamma-ray bursts? How do solar flares generate high-energy particles? How do pulsars work? What is the origin of cosmic rays? What else out there is shining gamma rays?

This thing will switch on soon, and they may find the particle that creates reality.

Underground search for 'God particle'


A circular tunnel runs for 27km
under the French-Swiss border

At the foot of the Jura Mountains, where Switzerland meets France, is a laboratory so vast it boggles the mind.

But take a drive past the open fields, traditional chalets and petite new apartment blocks and you will look for it in vain.

To find this enormous complex, you have to travel beneath the surface.
One hundred metres below Geneva's western suburbs is a dimly lit tunnel that runs in a circle for 27km (17 miles).

Nature is much smarter than us. It might come up with a real surprise and that would be much more interesting - much more satisfying

The tunnel belongs to Cern, the European Centre for Nuclear Research. Though currently empty, over the next two years an enormous experiment will be installed here.

The Large Hadron Collider (LHC) is a powerful and impossibly complicated machine that will smash particles together at super-fast speeds in a bid to unlock the secrets of the Universe.

'New physics'

By recreating the searing-hot conditions fractions of a second after the Big Bang, scientists hope to see new physics, discover the sought-after "God particle", uncover new dimensions and even generate mini-black holes.

When completed, two parallel tubes will carry high-energy particles called protons in opposite directions around the tunnel at close to the speed of light.


The Atlas experiment will join the
search for the Higgs boson at Cern

The tunnel's huge circumference provides only the slightest of bends. Nevertheless, around 5,000 superconducting magnets are needed to steer and focus the particles around the tubes.

"When the coils are energised there is one jumbo jet - 500 tonnes - per metre pushing outwards," says LHC project leader Lyn Evans.

Along the way, the proton beams will pass through enormous experimental instruments called detectors where they will cross.

When some of these protons collide at high energy, heavier particles can appear amongst the debris.

Great quest

When the LHC is turned on in the latter half of 2007, physicists will scour this crash wreckage for signs of the Higgs boson.

The Higgs is nicknamed the God particle because of its importance to the Standard Model, the theory devised to explain how sub-atomic particles interact with each other.

The 16 particles that make up this model (12 matter particles and 4 force carrier particles) would have no mass if considered alone. So another particle - the Higgs boson - is postulated to exist to account for this omission.


The CMS is constructed from
different layers in an "onion"
structure

"The Standard Model is the best thing we've come up with so far," says Jim Virdee, spokesman for the team working on the Compact Muon Solenoid (CMS) detector.

But everyone recognises it is merely a stage on the way to something else. The Standard Model describes ordinary matter and yet astronomical observations show this makes up but a small part of the total Universe.

Needless to say, new theories are gaining ground and discoveries at the LHC could lead physicists towards a unified theory to explain how the Universe works.

"We are at a stage where the theorists do not know which direction to go in. The results from [our] experiment will determine which direction science takes," says Professor Virdee, who is based at Imperial College London, UK.

"We don't always like theorists to tell us what we should find. Nature is much smarter than us.
"It might come up with a real surprise and that would be much more interesting - much more satisfying."

Huge scale

The detectors at the LHC will count, trace and analyse the particles that emerge from the collisions between protons.

To call them experiments simply does not give an idea of their scale. The equipment weighs tens of thousands of tonnes and in some cases is as tall as a multi-storey building.


A giant cavern will house the
CMS detector at Cern

This week marked the inauguration of the enormous cavern at Cessy in France that will house the CMS. A 78m-long shaft leads up to the surface, through which the CMS will be lowered by crane early next year.

Both the CMS and its rival experiment, Atlas, are based on a cylindrical "onion" structure with several layers to perform different roles.

By 2010, nearly one billion collisions will take place every second in these detectors.

"CMS needs to collect a sample of several hundred collisions out of 40 million. And we have just three microseconds to decide whether a collision produced something interesting," Professor Virdee told the BBC News website.

High energy

After attending the CMS inauguration, we travelled just across the border to Switzerland, where the Atlas cavern is located.

Measuring 53m long, 30m wide and 35m high, it is taller than Canterbury Cathedral and is currently empty but for the support structures that will hold the detector in place.


The Atlas cavern could fit a
12-storey building inside it

"You're visiting at a good time; it won't look like this again," says Atlas technical co-ordinator Mark Hatch.

High radiation levels when the LHC is running mean access to these caverns will be forbidden when the machine is in operation, creating problems for the scientists.

The energies achieved by the experiment are 70 times greater than those of the Large Electron-Positron Collider (LEP) which previously occupied the tunnels at Cern.

Only by raising the bar will scientists be able to expand our current understanding of the Universe.

Whatever the discoveries ahead for physicists working at the LHC, the experiments will, according to its chief scientific officer, Jos Engelen, "keep physicists off street corners for a long time to come".

BBC NEWS | Science/Nature | Underground search for 'God particle'