Kerosene Engine Passes Design Milestone

Image credit: NASA

NASA is working on several next-generation propulsion concepts that could help to push future exploration of the solar system, and one of the furthest along is the RS-84 kerosene-fueled rocket engine. The RS-84 is being designed by the Rocketdyne division of Boeing and it recently passed a detailed technical design review. The final, full-scale prototype engine should be ready for testing in 2007. Kerosene is more compact than traditional hydrogen fuel, saving launch weight, and it’s much safer to handle.

The kerosene-fueled RS-84 engine, one of several technologies competing to power NASA’s next generation of launch vehicles, has successfully completed its preliminary design review.

The RS-84 is a reusable, liquid booster engine that will deliver a thrust level of 1 million pounds of force. The design of the prototype engine is being developed by the Rocketdyne Propulsion & Power Division of the Boeing Company, in Canoga Park, Calif., for NASA’s Next Generation Launch Technology Program.

The program, part of NASA’s Space Launch Initiative, seeks to develop key space launch technologies ? engines and propulsion systems, hardware and integrated launch systems ? that will provide the foundation for America’s future space fleet.

The preliminary design review is a lengthy technical analysis that evaluates engine design according to stringent system requirements. The review ensures development is on target to meet Next Generation Launch Technology program goals: improved safety, reliability and cost. The review is conducted when the engine design is approximately 50 percent complete and engine drawings are approximately 10 percent complete.

“We’ve cleared our first major hurdle and the foundation is set for ensuring delivery of a safe, cost effective engine that will meet the next-generation launch requirements of NASA and the Department of Defense,” said Danny Davis, project manager for the RS-84 project at NASA’s Marshall Space Flight Center in Huntsville, Ala.

“We have a highly experienced team working on this unique design challenge,” Davis added. “I am very proud of the creativity offered by Rocketdyne, and of the thorough, constructive analysis provided by NASA’s insight team.”

The design team’s next major program milestone is the “40k” preburner test, a series of test-firings of a nearly full-scale preburner yielding 40,000 pounds of thrust. The test series, which will be conducted at NASA’s Stennis Space Center in Bay St. Louis, Miss., is scheduled to be completed in September. The final RS-84 prototype is expected to begin full-scale test firing by the end of 2007.

The RS-84 is one of two competing efforts now under way to develop an alternative to conventional, hydrogen-fueled engine technologies. The RS-84 is a reusable, staged combustion rocket engine fueled by kerosene ? a relatively low-maintenance fuel with high performance and high density, meaning it takes less fuel-tank volume to permit greater propulsive force than other technologies. That benefit translates to more compact engine systems, easier fuel handling and loading on the ground, and shorter turnaround time between launches. All these gains, in turn, reduce the overall cost of launch operations, making routine space flight cheaper and more attractive to commercial enterprises.

“No engine yet conceived meets the expectations of high reliability, high reusability mission life and responsiveness that is part of the RS-84 design,” Davis said. “Our design incorporates the latest in materials development, advanced software to monitor and predict problems, and lessons learned from past engine technology efforts.”

“The RS-84 preliminary design was shown to satisfy NASA’s goals, supporting an order of magnitude improvement in safety/reliability and operating cost,” said Roger Campbell, deputy program manager of Boeing Rocketdyne’s RS-84 engine team.

NASA’s Next Generation Launch Technology Program is developing and demonstrating innovative technologies in the areas of propulsion, systems integration and launch operations. The work of the program is intended to yield complete, next-generation space transportation systems that will provide low-cost space access and reinvigorate the U.S. space launch market, enabling stronger competition with international space agencies and private commercial entities, enabling stronger domestic and international competition.

Original Source: NASA News Release

NASA Considering What to Do with Shuttle Debris

As the Columbia accident investigation is wrapping up, NASA is considering what to do with the 84,000 pieces of debris; currently arranged on the floor of a hanger at the Kennedy Space Center. Several cities have requested pieces of debris for their memorials to the shuttle, and the agency is seeking guidance on how they can make it accessible while avoiding the “ghoulish factor” of putting it on display. Debris from the previous Challenger accident was packaged up and put into storage – that’s unlikely to happen with Columbia.

Atlas V Launches Rainbow 1

Image credit: ILS

An Atlas V rocket lifted off from Florida’s Cape Canaveral on Thursday carrying the Rainbow 1 direct-to-home broadcast satellite into orbit. The rocket lifted off at 2345 GMT (7:45pm EDT) and the satellite separated from the Centaur upper stage one hour and 40 minutes later. The launch was delayed 25 minutes because of weather and technical problems. This is the 66th successful flight for the Atlas line of rockets.

International Launch Services (ILS) and Lockheed Martin (NYSE: LMT) successfully launched the Rainbow 1 satellite today ? the third flight for the Atlas V vehicle since the rocket debuted last summer.

This mission, designated AV-003, also marked the 66th consecutive successful flight for the Atlas rocket family, built by Lockheed Martin Space Systems Co. of Denver, Colo. The satellite is an A2100 model, built by Lockheed Martin Commercial Space Systems of Newtown, Pa. Cablevision?s RLDBS project will use the high-powered satellite to introduce its Rainbow direct-to-home broadcast services to the contiguous United States.

Liftoff was at 7:45 p.m., with separation of the satellite occurring 1 hour and 40 minutes later. The Atlas V rocket was flown in its ?521? configuration, meaning it was fitted with a 5-meter-diameter fairing and two solid rocket motors. The larger fairing was chosen to accommodate the satellite?s sophisticated antenna array.

The Atlas V?s Centaur upper stage vehicle released the satellite into a nearly perfect transfer orbit. The apogee, or high point, was 35,843 km (target was 35,845 km); perigee, or low point, was on target at 3,790 km; and inclination was also right on target at 17.54 degrees.

?With another successful Atlas flight, we continue to demonstrate the reliability that our commercial and government customers have come to expect from ILS,? said Mark Albrecht, president of ILS. ?We?re honored that Cablevision chose the Lockheed Martin team to build a great satellite and launch it on a great rocket.??

This was the fourth mission and fourth success of the year for ILS, of McLean, Va., a joint venture of Lockheed Martin and two Russian companies. ILS markets and manages the missions for the Atlas and the Russian-built Proton and Angara launch vehicles.

?Today?s launch is an excellent example of the synergies inherent in Lockheed Martin?s businesses,? said Ted Gavrilis, president of Lockheed Martin Commercial Space, which arranged for the launch as a delivery-in-orbit mission. ?Our A2100 satellite and the ILS-provided Atlas V make a powerful combination for mission success, and we are proud to be part of launching a new direct-to-home service for Cablevision.?

ILS was formed in 1995 to provide launch services to customers worldwide, including technical, management and marketing expertise. Lockheed Martin?s partners in the venture are Khrunichev State Research and Production Space Center and RSC Energia. ILS offers the broadest range of launch services in the world along with the highest reliability in the industry. For more information, visit

Original Source: ILS News Release

Metallic Stars Yield Planets

Image credit: NASA

A survey of stars in our neighbourhood has revealed those rich in metals, such as iron and titanium, are five times more likely to have planets orbiting them. The survey of 61 stars with planets and 693 stars without, revealed a distinct difference in the ‘metalicity’ of stars. Debra Fisher from the University of California, Berkley, says, “If you look at the metal-rich stars, 20 percent have planets. That’s stunning.” (contributed by Darren Osborne)

A comparison of 754 nearby stars like our sun – some with planets and some without – shows definitively that the more iron and other metals there are in a star, the greater the chance it has a companion planet.

“Astronomers have been saying that only 5 percent of stars have planets, but that’s not a very precise assessment,” said Debra Fischer, a research astronomer at the University of California, Berkeley. “We now know that stars which are abundant in heavy metals are five times more likely to harbor orbiting planets than are stars deficient in metals. If you look at the metal-rich stars, 20 percent have planets. That’s stunning.”

“The metals are the seeds from which planets form,” added colleague Jeff Valenti, an assistant astronomer at the Space Telescope Science Institute (STScI) in Baltimore, Md.

Fischer will present details of the analysis by her and Valenti at 1:30 p.m. Australian Eastern Standard Time (AEST) on Monday, July 21, at the International Astronomical Union meeting in Sydney, Australia.

Iron and other elements heavier than helium – what astronomers lump together as “metals” – are created by fusion reactions inside stars and sown into the interstellar medium by spectacular supernova explosions. Thus, while metals were extremely rare in the early history of the Milky Way galaxy, over time, each successive generation of stars became richer in these elements, increasing the chances of forming a planet.

“Stars forming today are much more likely to have planets than early generations of stars,” Valenti said. “It’s a planetary baby boom.”

As the number of extrasolar planets has grown – about 100 stars are now known to have planets – astronomers have noticed that stars rich in metals are more likely to harbor planets. A correlation between a star’s “metalicity” – a measure of iron abundance in a star’s outer layer that is indicative of the abundance of many other elements, from nickel to silicon – had been suggested previously by astronomers Guillermo Gonzalez and Nuno Santos based on surveys of a few dozen planet-bearing stars.

The new survey of metal abundances by Fischer and Valenti is the first to cover a statistically large sample of 61 stars with planets and 693 stars without planets. Their analysis provides the numbers that prove a correlation between metal abundance and planet formation.

“People have looked already in fair detail at most of the stars with known planets, but they have basically ignored the hundreds of stars that don’t seem to have planets. These under-appreciated stars provide the context for understanding why planets form,” said Valenti, who is an expert at determining the chemical composition of stars.

The data show that stars like the sun, whose metal content is considered typical of stars in our neighborhood, have a 5 to 10 percent chance of having planets. Stars with three times more metal than the sun have a 20 percent chance of harboring planets, while those with 1/3 the metal content of the sun have about a 3 percent chance of having planets. The 29 most metal-poor stars in the sample, all with less than 1/3 the sun’s metal abundance, had no planets.

“These data suggest that there is a threshold metalicity, and thus not all stars in our galaxy have the same chance of forming planetary systems,” Fischer said. “Whether a star has planetary companions or not is a condition of its birth. Those with a larger initial allotment of metals have an advantage over those without, a trend we’re now able to see clearly with this new data.”

The two astronomers determined metal composition by analyzing 1,600 spectra from more than 1,000 stars before narrowing the analysis to 754 stars that had been observed long enough to rule a gas giant planet in or out. Some of these stars have been observed for 15 years by Fischer, Geoffrey Marcy, professor of astronomy at UC Berkeley, and colleague Paul Butler, now at the Carnegie Institution of Washington, in their systematic search for extrasolar planets around nearby stars. All 754 stars were surveyed for more than two years, enough time to determine whether a close-in, Jupiter-size planet is present or not.

Though the surfaces of stars contain many metals, the astronomers focused on five – iron, nickel, titanium, silicon and sodium. After four years of analysis, the astronomers were able to group the stars by metal composition and determine the likelihood that stars of a certain composition have planets. With iron, for example, the stars were ranked relative to the iron content of the sun, which is 0.0032%.

“This is the most unbiased survey of its kind,” Fischer emphasized. “It is unique because all of the metal abundances were determined with the same technique and we analyzed all of the stars on our project with more than two years of data.”
Fischer said the new data suggest why metal-rich stars are likely to develop planetary systems as they form. The data are consistent with the hypothesis that heavier elements stick together easier, allowing dust, rocks and eventually planetary cores to form around newly ignited stars. Since the young star and the surrounding disk of dust and gas would have the same composition, the metal composition observed from the star reflects the abundance of raw materials, including heavy metals, available in the disk to build planets. The data indicate a nearly linear relationship between amount of metals and the chance of harboring planets.

“These results tell us why some of the stars in our Milky Way galaxy have planets while others do not,” said Marcy. “The heavy metals must clump together to form rocks which themselves clump into the solid cores of planets.”

The research by Fischer and Valenti is supported by the National Aeronautics and Space Administration, the National Science Foundation, the Particle Physics and Astronomy Research Council (PPARC) in the United Kingdom, the Anglo-Australian Observatory, Sun Microsystems, the Keck Observatory and the University of California’s Lick Observatories.

Original Source: Berkeley News Release

Fewer Asteroids Threaten the Earth

Image credit: NASA

Researchers have built a computer simulation that better predicts how large asteroids will interact with the Earth’s atmosphere. They found that more asteroids blow up in the atmosphere than previously thought, reducing the risk of them hitting populated areas or causing tidal waves. Their model says that an asteroid has to be 200 metres in diameter or above before it can get through the atmosphere, and these only hit the Earth once every 170,000 years.

Researchers from Imperial College London and the Russian Academy of Sciences have built a computer simulation that predicts whether asteroids with a diameter up to one kilometre (km) will explode in the atmosphere or hit the surface.

The results indicate that asteroids with a diameter greater than 200 metres (the length of two football pitches) will hit the surface approximately once every 160,000 years – way down on previous estimates of impacts every 2,500 years.

The findings also predict that many more asteroids blow up in the atmosphere than previous estimates, which means the hazard posed by impact-generated tidal waves or tsunamis is lower than previous predictions. The researchers suggest that proposals to extend monitoring of Near Earth Objects (NEO) to include much smaller objects should be reviewed.

Dr Phil Bland of Imperial’s Department of Earth Science and Engineering and a Royal Society University Research Fellow, said:

“There is overwhelming evidence that impacts from space have caused catastrophes for life on Earth in the past, and will do so again.

“On the Moon it’s easier to track the number, frequency and size of collisions because there is no atmosphere, so everything hits the surface. On Earth the atmosphere acts like a screen and geological activity erodes many craters too.

“Massive impacts of the type thought to have wiped out the dinosaurs leave an indelible print on the Earth but we have not been able to accurately document the effect of smaller impacts. Now, we have a handle on the size of ‘rock’ we really need to worry about and how well the Earth’s atmosphere protects us.”

When small asteroids hit the atmosphere the two forces collide like two objects smashing together, which often breaks the asteroid into fragments. Until now, scientists have relied on the ‘pancake’ model of asteroid impact to calculate whether the asteroid will explode in the atmosphere. This treats the cascade of fragments as a single continuous liquid that spreads out over a larger area – to form a ‘pancake’. But a new model known as the ‘separate fragment’ (SF) model, which was developed by co-author of the study, Dr Natalya Artemieva of the Russian Academy of Science, has challenged this approach.

“While the pancake model can accurately predict the height from the Earth’s surface at which the asteroid will break up, it doesn’t give an accurate picture of how the asteroid will impact,” explains Dr Bland. “The SF model tracks the individual forces acting on each fragment as it descends through the atmosphere.”

To create a more accurate model of how asteroids interact with the atmosphere the researchers ran more than 1,000 simulations using both models. Objects made of either iron or stone, known as ‘impactors’, were used to reflect the composition of asteroids and experiments were run with varying diameters up to 1 km.

The researchers found the number of impacts for iron impactors were comparable using both models. For stone the pancake model significantly overestimated the survivability rate across the range used.

The SF simulations also allowed the researchers to define the different styles of fragmentation and impact rates for iron and stone, which correspond closely with crater records and meteorite data.

“Our data show that over most of the size range we investigated stony asteroids need to be 1,000 times bigger than the iron ones to make a similar sized crater. Much larger objects are disrupted in the atmosphere than previously thought.

“But we are not out of the woods yet,” added Dr Bland “asteroids that fragment in the atmosphere still pose a significant threat to human life.”

Dr Phil Bland is a member of the Meteorite and Impact Group that includes scientists from Imperial College London and the Natural History Museum.

Original Source: Imperial College News Release

Shuttle Program’s Flaws Will Be Revealed

Investigators working to determine the cause of the space shuttle Columbia disaster are expecting to reveal some serious problems with NASA’s program that oversees shuttle safety. The investigation team interviewed 72 NASA employees and contractors over a period of months and learned there were serious gaps in the agency when it came to safety. Some inspections had been removed to cut costs; quality assurance staff weren’t allowed to perform “spot checks”; and the agency was using hopelessly outdated testing equipment.

Mars Express Says Goodbye to the Earth and Moon

Image credit: ESA

Now well on its way to the Red Planet, the European Space Agency’s Mars Express spacecraft took a farewell image of the Earth and Moon. The photo was snapped on July 3 when the spacecraft was 8 million kilometres away from the Earth. The picture was taken as part of a series of tests the ESA is doing to make sure the Mars Express’ cameras and instruments are working properly. Once it reaches Mars in late December, the spacecraft will be able to resolve objects on the surface of Mars as small as 2 metres.

A unique view of our home planet and its natural satellite ? the Moon – is one of the first data sets coming from ESA’s Mars Express.

?It is very good news for the mission,? says ESA’s Mars Express Project Scientist, Agustin Chicarro. These and other data, such as those recording the major constituents of Earth as seen from space, are the actual proof that the instruments on board Mars Express, launched 2 June 2003, are working perfectly.

The routine check-outs of Mars Express’s instruments and of the Beagle-2 lander, performed during the last weeks, have been very successful. “As in all space missions little problems have arisen, but they have been carefully evaluated and solved. Mars Express continues on its way to Mars performing beautifully”, comments Chicarro.

The views of the Earth/Moon system were taken on 3 July 2003 by Mars Express’s High Resolution Stereo Camera (HRSC), when the spacecraft was 8 million kilometres from Earth. The image taken shows true colours; the Pacific Ocean appears in blue, and the clouds near the Equator and in mid to northern latitudes in white to light grey. The image was processed by the Instrument Team at the Institute of Planetary Research of DLR, Berlin (Germany). It was built by combining a super resolution black and white HRSC snap-shot image of the Earth and the Moon with colour information obtained by the blue, green, and red sensors of the instrument.

?The pictures and the information provided by the data prove the camera is working very well. They provide a good indication of what to expect once the spacecraft is in its orbit around Mars, at altitudes of only 250-300 kilometres: very high resolution images with brilliant true colour and in 3D,? says the Principal Investigator of the HRSC, Gerhard Neukum, of the Freie Universit?t of Berlin (Germany). This camera will be able to distinguish details of up to 2 metres on the Martian surface.

Another striking demonstration of Mars Express’s instruments high performance are the data taken by the OMEGA spectrometer. Once at Mars, this instrument will provide the best map of the molecular and mineralogical composition of the whole planet, with 5% of the planetary surface in high resolution. Minerals and other compounds such as water will be charted as never before. As the Red Planet is still too far away, the OMEGA team devised an ingenious test for their instrument: to detect the Earth?s surface components.

As expected, OMEGA made a direct and unambiguous detection of major and minor constituents of the Earth?s atmosphere, such as molecular oxygen, water and carbon dioxide, ozone and methane, among other molecules. “The sensitivity demonstrated by OMEGA on these Earth spectra should reveal really minute amounts of water in both Martian surface materials and atmosphere,” says the Principal Investigator of OMEGA, Jean Pierre Bibring , from the Institut d’Astrophysique Spatiale, Orsay, France.

The experts will carry on testing Mars Express?s instruments up till the arrival to the Red Planet, next December. The scientists agree on the fact that these instruments will enormously increase our understanding of the morphology and topography of the Martian surface, of the geological structures and processes – active now and in the past, and eventually of Mars?s geological evolution. With such tools, Mars Express is also able to address the important ?water? question, namely how much water there is today and how much there was in the past. Ultimately, this will also tell us whether Mars had environmental conditions that could favour the evolution of life.

Original Source: ESA News Release

SOHO is Back in Business

Image credit: ESA/NASA

ESA/NASA’s SOHO spacecraft is back to full capacity after a 9-day long blackout. On June 19, the pointing mechanism on the spacecraft’s high-gain antenna malfunctioned; however, controllers were able to retrieve data through its low-gain antenna using larger receiving dishes on Earth. The spacecraft was repositioned this week to let its antenna point directly at Earth. By repositioning it every three months, mission controllers don’t expect they will lose more than a fraction of data, allowing the spacecraft to continue operations for another five years.

ESA/NASA’s solar watchdog, SOHO, is back to full operation after its predicted 9-day-long high-gain antenna blackout. Engineers and scientists are now confident that they understand the situation and can work around it in the future to minimise the data losses.

Since 19 June 2003, SOHO’s high-gain antenna (HGA), which transmits high-speed data to Earth, has been fixed in position following the discovery of a malfunction in its pointing mechanism. This resulted in a loss of signal through SOHO’s usual 26-metre ground stations on 27 June 2003. However, 34-metre radio dishes continued to receive high-speed transmissions from the HGA until 1 July 2003.

Since then, astronomers have been relying primarily on a slower transmission rate signal, sent through SOHO’s backup antenna. It can be picked up whenever a 34-metre dish is available. However, this signal could not transmit all of SOHO’s data. Some data was recorded on board, however, and downloaded using high-speed transmissions through the backup antenna when time on the largest, 70-metre dishes could be spared.

SOHO itself orbits a point in space, 1.5 million kilometres closer to the Sun than the Earth, once every 6 months. To reorient the HGA for the next half of this orbit, engineers rolled the spacecraft through a half-circle on 8 July 2003. On 10 July, the 34-metre radio dish in Madrid re-established contact with SOHO’s HGA. Then on the morning of 14 July 2003, normal operations with the spacecraft resumed through its usual 26-metre ground stations, as predicted.

With the HGA now static, the blackouts, lasting between 9 and 16 days, will continue to occur every 3 months. Engineers will rotate SOHO by 180 degrees every time this occurs. This manoeuvre will minimise data losses. Stein Haugan, acting SOHO project scientist, says “It is good to welcome SOHO back to normal operations, as it proves that we have a good understanding of the situation and can confidently work around it.”

Original Source: ESA News Release

Clusters without a Home

Image credit: Hubble

Thousands of globular star clusters wander aimlessly between galaxies, in what was once thought to be ’empty space’. This is the finding of a joint US-UK project announced today at the International Astronomical Union General Assembly in Sydney. The group, lead by Dr. Michael West of the University of Hawaii, believes these clusters were ‘torn’ away from their parent galaxies and now drift as orphans. (contributed by Darren Osborne)

US and UK astronomers have discovered a population of previously unknown star clusters in what was thought to be the empty space between galaxies. The research is being presented today at the International Astronomical Union?s 25th General Assembly being held in Sydney, Australia, by Dr. Michael West of the University of Hawaii.

Most galaxies are surrounded by tens, hundreds or even thousands of ancient star clusters, which swarm around them like bees around a hive. Our own Milky Way galaxy has about 150 of these ?globular clusters?, as they are called. Globular clusters are systems of up to a million stars compacted together by gravity into dense sphere-shaped groupings. Studies of globular clusters have provided many important insights over the years into the formation of their parent galaxies.

The discovery of this new type of star cluster was made using images obtained last year with the Hubble Space Telescope and the giant 10-meter Keck Telescope on Mauna Kea, Hawaii. ?We found a large number of ?orphaned? globular clusters,? said Dr West. ?These clusters are no longer held within the gravitational grip of galaxies, and seem to be wandering freely through intergalactic space like cosmic vagabonds.?

Although the lonely existence of such star clusters had been predicted for half a century, it is only now that astronomers have finally been able to confirm their existence. Dr West?s team published preliminary findings about its discovery in April this year, and is today presenting new results at the International Astronomical Union?s 25th General Assembly, being held in Sydney, Australia.

?The new data from the Hubble Space Telescope and Keck Telescope confirm our discovery, and are providing new insights to the origin of these objects,? said Dr West.

According to West, these globular star clusters probably once resided in galaxies just like most of the normal globular clusters that we see in nearby galaxies today. However, the pull of gravity from a passing galaxy can rip stars and star clusters loose — in some cases entire galaxies can be damaged or destroyed by violent collisions or by the collective gravitational pull from their galactic neighbors.

It is thought that the partial or complete destruction of their parent galaxies spilled the globular star clusters into intergalactic space.

Finding these globular clusters hasn?t been easy. With only one exception, all of the intergalactic globular clusters the teams have detected are so far away (millions of light-years) that they just look like tiny points of light in a vast sea of blackness.

?Because they’re so far away these objects are very faint, almost a billion times fainter than the unaided human eye can see,? said Dr West. ?Detecting such faint objects pushes the limits of even what the Hubble Space Telescope can do.?

?By studying these intergalactic vagabonds in greater detail we hope to learn more about the numbers and types of galaxies that may have been destroyed so far during the life of the universe,? said Dr West. ?Some of these star clusters might also eventually be ?adopted? by other galaxies if they stray close enough to be captured by their gravity.?

The researchers are currently analyzing new Hubble Space Telescope images they recently obtained, and are planning to obtain more at the end of this year.

Original Source: University of Hawaii News Release

My Two Favorite Radio Programs

If you’re interested in science and discovery in general, I’d like to suggest two weekly, hour-long radio shows that you should tune into – through the Internet.

  • Quirks and Quarks – Every Canadian reader will know exactly what I’m talking about. This is a weekly radio show on the Canadian Broadcasting Channel hosted by Bob McDonald. They have archives available online going back almost 10 years.
  • NPR Science Friday – Every Friday, NPR’s Talk of the Nation is taken over by Ira Flatow to discuss the latest happening in science. It’s a great show.

Both are well worth your time. Check them out.

Fraser Cain
Universe Today