KC AstroEvents

2004
Cassini at Saturn

May
Astronomy Day

April 12
Yuri's Night

Spring 03
Star Prepares to Blow

2004
RHESSI Studies Solar Flares

2004
First Solar Sail

2004
RHESSI Studies Solar Flares

The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) launched as HESSI in 2002 and was renamed RHESSI in honor of late co-creator Reuven Ramaty.

RHESSI is the first space mission named after a NASA scientist.

RHESSI is part of NASA's Small Explorer Program. 

RHESSI's primary mission is to explore the basic physics of particle acceleration and explosive energy release in solar flares. 

RHESSI has achieved its Minimum Science Requirements:

1. Perform hard X-ray (greater than 20 keV) imaging spectroscopy of solar flares with better than 4 arcsecond spatial resolution and better than 3 keV energy resolution.
2. Perform high resolution (better than 3 keV FWHM at l MeV) spectroscopy of gamma-ray lines in solar flares.
3. Obtain observations of at least a hundred hard X-ray flares and ten gamma-ray (greater than 300 keV) flares.

HESSI UC Berkeley Site

NASA Goddard Space Flight Center HESSI Site
[links open in new window]

2004
Mars Odyssey Mapping

NASA broke its Red Planet losing streak (0-2) with the Mars Odyssey spacecraft. 

The $300 million orbiter reached Mars in 2001 after a journey of 286 million miles (460 million km).

Mars Odyssey is searching for water, map surface minerals and measure radiation levels -- observations that could provide clues about possible extraterrestrial life as well as check for possible hazards for future colonists.

Odyssey will join the Mars Global Surveyor, which has been circling Mars since 1997, snapping hundreds of thousands of high resolution pictures.

2004
First Solar Sail

Cosmos 1 will be the first solar sail EVER! It's the first time a NONPROFIT ORGANIZATION is paying for a spacecraft.

Cosmos 1 is a 30 meter diameter sail, configured in 8 triangular blades. The sails are made of 5-micron-thin aluminized reinforced Mylar, so the entire spacecraft only weighs 40 kilograms. It will be launched by Volna, a submarine launched converted ICBM. That's right, an InterContinental Ballistic Missile launched from a SUBMARINE will propel Cosmos 1 into a 850 kilometer near polar orbit!

The submarine launch will be from the Barents Sea north of Murmansk.

A test of the solar sail deployment was conducted in a Volna-launched, suborbital flight in July 2001.

How does a solar sail work? The solar sail will use the pressure of sunlight to increase its orbital energy and raise its orbital altitude. The sail is controlled by pitching the blades, thus turning the direction of the solar force. The inflatable tubes keep the sail rigid.

The great advantage of a solar sail is that it REQUIRES NO FUEL. Standard chemical rockets give spacecrafts a quick boost into Earth orbit. The spacecraft then coasts most of the way to its destination, with some small blasts from thrusters to adjust its trajectory. This requires a lot of fuel. Solar sails give a very low thrust, but they can work continuously, pushing spacecraft faster and faster. A solar sail spacecraft can, in time, move the spacecraft even faster than a chemical rocket.

When the light from the Sun hits the surface of the solar sail the energy, or momentum, of photons (light particles) is transferred to the sail – as the light is reflected away, it gives the sail a slight "push." The force is controlled by the angle of the sail with respect to the Sun, adding to or subtracting from the orbital velocity.

WHY a solar sail? To demonstrate the technique for traveling between planets -- and someday, to the stars!

To the stars? Sure, once you get much beyond the orbit of Jupiter, energy from sunlight is too weak. But lasers can be directed at the sails. Lasers stay in a tight beam so that most of their energy can be imparted to the sail, and not diffuses into space. Very large lasers could be used to help us travel to other stars. In the future, people may travel to distant stars using laser powered solar sails.

AstroNews is an electronic newsletter. Stay abreast of astronomy and extraterrestrial news. 
A free service of Kahl Consultants. 
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