Posts Tagged ‘nasa’

Extrasolar Planet Finding

Monday, September 15th, 2008 by Bellatrix

As of September 2008 a total of 309 extrasolar planets have been discovered. So far only massive gas giants, like Jupiter, have been detected, although some as small as Neptune. No terrestrial, or earth like planets, have been discovered yet. This is because of the current limitations on the technology, or the method, used to detect planets. However, this will hopefully be changing soon.

Currently it is difficult to locate earth-sized planets because they are very small, and do not give off much reflected light from their stars. So far no planet has been bright enough on its own to be detected by our telescopes. We can only detect planets by the small gravitational effects these planets have on their host stars. Planets do not have much mass compared to stars but the little mass they have exerts a pull on their stars; it makes them wobble slightly. We can use the Doppler effect to measure this wobble. The Doppler effect makes it so that the light from the star is bluer when moving toward us, and redder when moving away from us. So when watching a star with a planet around it, the pull from the planet as it orbits the star causes this shift in the observed light from the star, thus we know the planet is there. However, the mass of earth-sized planets is too small to create any noticeable wobble.

However, progress is definitely being made. The Subaru Telescope, located atop mount Mauna Kea in Hawaii, has an 8.2-meter mirror and has recently started scanning nearby stars looking for planets. There are eight innovative cameras and spectrographs at Subaru optimized for various astronomical investigations in optical and near-infrared wavelengths. One of these cameras is called HiCIAO, or High Contrast Instrument for the Subaru Next Generation Adaptive Optics. It is designed to block out the harsh direct light from a star, so that nearby faint objects such as planets can be viewed. The new adaptive optics system uses 188 actuators behind a deformable mirror to remove the atmospheric distortion from its view, allowing Subaru Telescope to observe close to its theoretical performance limits. The Subaru Telescope hopes to be the first to directly observe a planet outside our solar system.

Now even though Subaru hopes to be the first to direct image a planet, it still cannot detect an earth-sized planet. NASA was planning on launching a space telescope for this purpose called the terrestrial planet finder. This would consist of two observatories planned to not only detect these types of planets but also even study their characteristics such as size, distance from star, and even atmospheric components. However, due to budget cuts at NASA the project has been postponed indefinitely. I think until this project, or a similar one is funded and launched, we will continue to be limited by our current earth-based telescopes, and earth-like planets will remain outside our view.

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Will Solar Sails Ever Catch the Cosmic Wind?

Monday, September 8th, 2008 by Evan Finnes

Imagine a space exploration vehicle that needs little fuel, and can continually accelerate as long as it is in contact with solar radiation. This is the idea behind solar sails, which were first dreamt up by the great German astronomer, Johannes Kepler. Since then they have been in the minds of many astronomers, engineers, and science fiction authors. To date there has not been a successful deployment of a solar sail.

A spacecraft would deploy a large membrane of reflective material, this “sail” would reflect protons delivered by solar radiation. This exchange of momentum by reflecting photons would cause a resulting thrust of the space craft. Even though such a sail would generate a continuous acceleration, this technology is thought to be impractical for long distance travel because of the enormous sail that would be needed, the relatively slow start acceleration, and the small amounts of radiation available at distances far from the sun. By aiming the sail against the Sun, a reverse thrust, or deceleration would be achieved, making solar sails a fuel saving technology useful in repositioning satellites in Earth’s orbit or slowing satellites as they approach other planets.

NASA and Ames Research Center recently built NanoSail-D. The Sail was made from a composite of Aluminum and space age plastic. When opened the sail was suppose to span 100 square feet, and the entire space craft weighed less than 10 pounds. The purpose of this mission was to see if sails could be used to direct a satellite back into the Earth’s Atmosphere where it can be burned up, thus leaving less clutter in Earth’s orbit due to unused satellites.

However, not all missions end in glory. On August 2, the NanoSail-D space craft was launched from the Kwajalein Atoll aboard the SpaceX Falcon 1 rocket. There was a system failure in stage 1 of the launch, and the craft never reached orbit. This resulted in the loss of NanoSail-D. NASA has a spare NanaSail-D and is currently working on plans for a future launch. A similar mission also failed in 2005, when the Planetary Society and Cosmos Studios launched Cosmos 1.

If the technology for making and deploying large sails becomes available the practicality for deep space missions would change. It took Voyager more than three decades to escape the solar system using conventional rockets, but a spacecraft using large and efficient sails would be able to catch up to the Voyager spacecrafts in less than ten years.

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Our Next Giant Leap

Saturday, August 30th, 2008 by Evan Finnes

One-fifth of the entire world population watched the live broadcast of the first Moon-walk, so it is no surprise that we all remember or have heard those famous words spoken by Neil Armstrong in 1969. The Apollo program and lunar landings aided the advancement of many fields of engineering, and is considered by many to be the greatest achievement of mankind. Nearly forty years after the end of the Apollo missions, NASA finally plans on returning to the Moon.

Before NASA returns man to the Moon, they plan on doing extensive studies. The first mission to the Moon will be the Lunar Reconnaissance Orbiter (“LRO”), which is scheduled to launch by the end of this year or early next year. The LRO will be equipped with the most sophisticated technology ever sent to the Moon–including instruments to make detailed 3-D maps of the entire lunar surface, locate subsurface water-ice, and record radiation levels to help develop technologies which will ensure the safety of future crews.

Launching with the LRO is the Lunar Crater Observation and Sensing Satellite (“LCROSS”). In 1999, NASA’s Lunar Prospector detected the spectral signature of hydrogen in the Moon’s permanently shadowed polar craters. LCROSS will impact the Moon in one of these craters. The impact will send a plume of material into space, which will be observed by a near-infrared camera, which will analyze the plume for traces of water. Presence of water on the Moon would be an important natural resource for a future lunar colony.

NASA plans on having mankind back on the Moon by 2020. Utilizing the new equipment which is currently being developed as part of the Constellation program, four astronauts will land on the Moon aboard the new Altair Lunar Lander, which will provide life support for the initial week long mission to the Moon. The Lunar Lander will be launched into low-Earth orbit aboard an Ares V Rocket, where it will rendezvous with the Orion crew vehicle.

Returning man to the Moon is the important first step in NASA’s new Moon Mars and beyond initiative proposed by George Bush. The Lunar surface will be explored and studied in an attempt to learn how to build a successful space colony. Risks such as radiation and psychological trauma will have to be fully understood and overcome before any long-term manned missions to Mars, or elsewhere, can be pursued. Having a colony on the Moon will also help us study how the Earth and Moon were formed, and giant telescopes on the Moon will not have the atmospheric interference which is a problem on Earth. Along with the many scientific advances which will follow future lunar landings, returning to the Moon will renew the general population’s interest in space exploration.

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GLAST and The Mystery of Gamma Ray Bursts

Tuesday, August 26th, 2008 by Bellatrix

It has been nearly three months now since GLAST was launched, NASA’s Gamma-ray Large Area Telescope. The telescope isn’t fully functional right now, but according to NASA’s website the telescope is up and running and so far passing all of the checks the engineers are laying out.

Gamma rays are some of the most powerful and mysterious objects detected in space so far. As their name entails they are short-lived bursts of gamma ray photons, having energies ranging from a thousand electron volts to several billion electron volts. They range in duration from a few tenths of a second to a few minutes. However, this very short duration makes them very hard to detect and gather data on, since by the time a telescope is alerted to a burst and pointed in the right direction the burst will be over.

Gamma ray bursts are not well understood. They weren’t discovered until the 1960’s, and as late as the 1990’s astronomers weren’t even sure if these bursts were coming from the edge of the solar system or the edge of the universe. However, with recent advancement in technologies we’ve been discovering much more about them, giving us clues to their origin. We now know there are two different classifications of gamma ray bursts. Long Duration ones are bursts lasting 2 seconds to a few minutes, short duration ones are shorter than 30 seconds. Astronomers think fundamentally different processes create them. Long bursts are believed to be generated billions of light years away by the death or collapse of very massive stars, or Wolf Rayet stars. Short bursts are less understood, but may be created in very high energy collisions like between two neutron stars or a neutron star and black hole.

GLAST will be able to cover much more of the sky than the current gamma ray satellite, SWIFT. The GLAST team is currently in the process of checking the validity of the burst locations it detects. So far, GLAST has detected 12 bursts, and other telescopes have so far verified four of these bursts. Once all the checks have been performed and the team operations are running smoothly GLAST should start making some great discoveries. It will be able to gather data on a much higher number of bursts and tell us about the area from which they originated. Matching up the bursts with data about the originating area from before the bursts will hopefully tell us more about how they are created, such as if a known super giant star is in the vicinity of the bursts before but not after the burst.

New technology for this purpose is quite exciting. There are so many strange and mysterious things in the Universe we still don’t understand; to have something that may lead to a new discovery in astronomy is thrilling. It will be important to keep an eye on the data coming in once GLAST really gets going.

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