Science and Space

space and astronomy articles.

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Gravity Assist

I tried many sites which explains me how "Gravity Assist" works to change the speed and orbit of a spacecraft. In my opinion the following site is the best.

http://www.sciam.com/askexpert_question.cfm?articleID=00070374-FE82-1152-BE8283414B7F0000&catID=3&chanID=sa005

posted by: kyawoo at 20:57 | link | comments |
space science

Why precious materials are used to collect solar wind?

The crashed Genesis capsule was outfitted with five collector arrays, each of which was tiled with 55 hexagonal wafers constructed of gold, sapphire, diamonds, and silicon.Why construct the particle collectors from such precious materials?

Because, in addition to making jewelry sparkle, the gems and precious metals aboard Genesis have extremely low impurity levels. And that’s critical to the analysis of the solar wind, the particles of which contain infinitesimal traces of the 83 naturally occurring elements. If one of the collecting disks left Earth contaminated with even a tiny dollop of, say, magnesium, then researchers would be hard-pressed to know whether the sun was actually ejecting lots of the metallic element once the disk returned to the planet.

Why all the different materials? Each gem or metal is uniquely adept at capturing a specific element. For example, pre-mission testing revealed that aluminum layered atop sapphire was perfect for collecting noble gases such as helium and neon. Diamonds, meanwhile, are best for collecting oxygen, since they naturally contain so little of the common, life-giving element.

The most prevalent element in the wafers was silicon, which is why NASA was so concerned about preventing a crash. Silicon is invaluable because of its purity. But it’s also somewhat fragile, and a large jolt could shatter the collector arrays, leading to the contamination of the solar-wind samples that NASA spent approximately $260 million trying to gather. Unfortunately, that’s exactly what may have happened in the Utah desert today.

posted by: kyawoo at 21:01 | link | comments |
unmanned missions, space science, sun

Ongoing Space Missions(6)

INTErnational Gamma-Ray Astrophysics Laboratory(INTEGRAL)

Launched 17 Oct 2002

The objective -

to get a a new insight into the most violent and exotic objects of the Universe, such as black holes, neutron stars, active galactic nuclei and supernovae.

to understand processes such as the formation of new chemical elements and the mysterious gamma-ray bursts, the most energetic phenomena in the Universe.

Mission Basics-

With INTEGRAL astronomers are gaining a new understanding of objects and processes that emit the most powerful electromagnetic radiation. The gamma-rays detected by INTEGRAL are a million times more energetic than visible light. The shorter the wavelength, the higher is the energy of the radiation. Red light has a wavelength of 700 nanometres (0.000 000 7 metres), violet light of 400 nanometres. INTEGRAL studies radiation with a wavelength from 0.2 to only 0.0008 nanometres.

Mission Cost-

€330 million at 2000 economic conditions (excluding launch and payload)

End of Mission extended until 2008

posted by: kyawoo at 22:23 | link | comments |
astronomy, unmanned missions

Volcanic ashes from Io

Jupiter’s moon Io is shooting tiny volcanic projectiles at passing spacecraft. They scorch through space traveling 670,000 mph, and they can even reach Earth. The Ulysses spacecraft discovered the fast-moving bits of ash in 1992, and encountered them again this year, raising new questions about the solar system’s weirdest meteoroids.

posted by: kyawoo at 20:14 | link | comments (2) |
unmanned missions, jupiter

Ongoing Space Missions(5)

(This is the fifth  part of the series "Ongoing Space Missions" in which I will try to inform the readers all about the spacecrafts still travelling or operating beyond near-earth orbit)

XMM-Newton

Launched     10 Dec 1999

The objective -

Placed in orbit around the Earth where the atmosphere cannot block celestial X-rays, the XMM-Newton space observatory studies some of the most violent space phenomena. Since its launch in 1999, the spacecraft has helped scientists to investigate a number of mysterious cosmic phenomena, such as:

· the interaction of black holes with their surroundings;

· the explosion of supernovae and their remnants;

· the origin of the powerful gamma-ray bursts;

· the hot gas filling the space between galaxies throughout the Universe;

                    · the evolution of the Universe itself by looking back to its origin.

Mission Basics-

XMM-Newton spacecraft was placed into a 48-hour elliptical orbit around the Earth. Inclined at 40o with a Southern apogee at 114 000 km, the perigee altitude is 7000 km.

Many celestial objects generate X-rays in extremely violent processes. But Earth’s atmosphere blocks out these X-rays. Only by placing X-ray detectors like XMM-Newtonin in space can such sources be detected, pinpointed and studied in detail.

XMM-Newton carries three very advanced X-ray telescopes. They each contain 58 high-precision concentric mirrors, delicately nested to offer the largest collecting area possible to catch the elusive X-rays. These Mirror Modules allow XMM-Newton to detect millions of sources, far more than any previous X-ray mission.

Mission Cost- 689 million Euros. This included the spacecraft design and development, the launch and the ground operations during the first two years.

End of Mission    until at least March 2006

posted by: kyawoo at 05:44 | link | comments (1) |

CubeSats

The space news that catches me today is CubeSats, low-cost satellites with promising future.

CubeSats are low-cost microsatellite that could be placed into Earth orbit for under $ 100,000. Cubesat bus measured 10 centimetres on a side, and weighed less than one kilogram.

Cubesats could be used for scientific missions (microgravity, biomedical, component testing, amateur radio) or personal (burial, photography).

posted by: kyawoo at 19:57 | link | comments |

Ongoing Space Missions(4)

(This is the fourth part of the series "Ongoing Space Missions" in which I will try to inform the readers all about the spacecrafts still travelling or operating beyond near-earth orbit)

Galaxy Evolution Explorer (GALEX)

Launched 28 April 2003

The objective -

To map the history and evolution of the Universe, 80 percent of the way back to the Big Bang. The mission aims to answer the questions:

What is the history of star formation in the Universe?

What do nearby galaxies look like in ultraviolet light?

When and where did the stars and elements we see today have their origins?

Mission Basics-

With sensitive ultraviolet detectors, a large field of view, and its location above the ultraviolet-absorbing atmosphere of the Earth, GALEX will perform ground breaking observations of the ultraviolet sky. GALEX will detect ultraviolet objects in the sky that are more than a million times fainter than objects we can see in visible light with our eyes from the darkest location on the ground. GALEX will also peer billions of years back into the history of the Universe.

Mission Cost- $ 16.5 million

End of Mission

September 2005

posted by: kyawoo at 11:34 | link | comments |
astronomy, unmanned missions

Ongoing Space Missions(3)

(This is the third part of the series "Ongoing Space Missions" in which I will try to inform the readers all about the spacecrafts still travelling or operating beyond near-earth orbit)

The Spitzer Space Telescope

Launched 25 August 2003

The objective -

to peer into regions of space which are hidden from optical telescopes.

Mission Basics-

Spitzer Space Telescope(formerly SIRTF, the Space Infrared Telescope Facility) was launched into an innovative Earth-trailing solar orbit. This means that it will not circle around the Earth. Instead, it will trail behind the Earth as the Earth orbits around the Sun. Spitzer will slowly drift away from the Earth at the rate of about 16,000,000 km per year.

Consisting of a 0.85-meter telescope and three cryogenically-cooled science instruments, Spitzer is the largest infrared telescope ever launched into space. Its highly sensitive instruments give us a unique view of the Universe. Many areas of space are filled with vast, dense clouds of gas and dust which block our view. Infrared light, however can penetrate these clouds, allowing us to peer into regions of star formation, the centers of galaxies, and into newly forming planetary systems. Infrared also brings us information about the cooler objects in space, such as smaller stars which are too dim to be detected by their visible light, extrasolar planets, and giant molecular clouds. Also, many molecules in space, including organic molecules, have their unique signatures in the infrared.

Because infrared is primarily heat radiation, the telescope must be cooled to near absolute zero (-459 degrees Fahrenheit or -273 degrees Celsius) so that it can observe infrared signals from space without interference from the telescope’s own heat. Also, the telescope must be protected from the heat of the Sun and the infrared radiation put out by the Earth. To do this, Spitzer carries a solar shield and launched into an Earth-trailing solar orbit. This unique orbit places Spitzer far enough away from the Earth to allow the telescope to cool rapidy without having to carry large amounts of cryogen (coolant).

The ability to see astronomical objects will clearly depend on the luminosity (brightness) of those objects. The Spitzer Space Telescope expects to be able to see bright galaxies out to redshifts of z = 4 or more, which corresponds to about 11.5 billion light-years. Since the observable Universe is thought to be some 12-15 billion light-years in size, it should be apparent that Spitzer has the capability of observing objects in the very distant (and young) Universe.

Mission Cost- $720 million

End of Mission

Estimated Lifetime: 2.5 years (minimum); 5+ years (goal)

posted by: kyawoo at 19:52 | link | comments |
astronomy, unmanned missions