Ariane 5 Launches Envisat Successfully

Image credit: Arianespace

After much anticipation, an Ariane 5 rocket blasted off from Kourou, French Guiana last night, carrying the European Space Agency’s Envisat environmental monitoring satellite into an 800km orbit. Once it reaches its final orbit, the 8000 kg Envisat will observe the Earth’s environment using ten instruments which measure the state of the land, ocean, ice cover and atmosphere. This is the first launch of an Ariane 5 since a problem last July that placed two satellites into incorrect orbits.

The eagerly awaited launch of ESA?s Envisat environmental monitoring satellite took place in Kourou, French Guiana, today at 22:07:59 hrs Kourou time (02:07:59 hrs CET). Envisat?s spectacular night-time launch also marked the return to business for Europe?s Ariane 5 launcher.

Lift-off was witnessed by dozens of cheering engineers, scientists and project members at the launch site and at ESA centres across Europe. Rising into a clear sky, the Ariane 5 propelled the Envisat towards a lofty vantage point some 800 km above the Earth?s surface.

Envisat ? the most ambitious Earth observation satellite ? follows in the footsteps of ESA?s successful ERS-1 and ERS-2 missions launched in the 1990s. It will boost Europe?s capacity to take part in the study of the Earth and its environment by supporting critical research programmes on global warming and climate change issues, as well as performing crucial tasks such as pollution and disaster monitoring .

After a flawless lift-off, the Ariane 5 placed Envisat into sun-synchronous orbit, allowing ESA ground controllers at the space operations centre in Darmstadt, Germany, to take full control for the first time of the most complex satellite ever built in Europe.

?This has been a particularly exciting day for ESA and the European space community as a whole,? said Jos? Achache, ESA?s Director of Earth Observation. ?Europe is taking an important lead in global observations for worldwide environmental needs and Envisat is going to make a significant impact on the future of remote sensing of the Earth?.

?The ten instruments on board Envisat, more than on any other satellite, cover a wide spectrum of phenomena, delivering evidence of the interactions between the atmosphere, the ocean, the polar ice caps, the vegetation as well as human activity at the surface of the Earth. We will be able to trace the smallest changes to the Earth?s surface anywhere on the globe. The importance of this mission has triggered great interest in the Earth-science community, both at a European level and worldwide.?

Commenting from Europe?s spaceport in French Guiana, Jacques Louet, ESA?s Envisat Programme Manager, admitted that there was a certain risk to pack so much know-how into just one satellite. ?However, if we want to have a comprehensive understanding, we must follow this path?, he said.

Given its sheer size, Envisat has involved almost all of Europe?s space industries in the development of numerous advanced technologies, particularly for the payload.

Envisat is expected to be declared operational after just a few weeks, once its payload has been checked out and the various data-recovery links set up. Then the satellite?s six-month long commissioning phase will begin, ensuring that the ten instruments are operating as specified and that we can start delivering validated products to our users.

?Now Envisat is in orbit, the culmination of many years? work really begins and we are looking forward to the environmental benefits the satellite is going to bring to Europe,? added Mr Achache.

The successful launch of Envisat also marked a return to service for the Ariane 5 launcher. It?s upper stage has undergone over 300 tests since last summer, following the failure of flight Ariane 510 to insert two satellites, including ESA?s Artemis, in the correct orbits. However, thanks to ion propulsion, the Artemis mission is turning into a success story, as the satellite is making its way to geostationary orbit, and nominal operations could start this summer.

Original Source: ESA News Release

Jupiter’s X-Ray Hotspot Puzzles Astronomers

Image credit: Chandra
A new image taken by the Chandra X-Ray Telescope shows puzzling, pulsating hotspots at Jupiter’s north and south poles. So far, scientists have no explanation for what could be causing these X-rays; although, they do coincide with other phenomena seen on the planet, including auroras; like those at the Earth’s poles.

This image of Jupiter shows concentrations of auroral X-rays near the north and south magnetic poles. While Chandra observed Jupiter for its entire 10-hour rotation, the northern auroral X-rays were discovered to be due to a single ‘hot spot’ that pulsates with a period of 45 minutes, similar to high-latitude radio pulsations previously detected by NASA’s Galileo and Cassini spacecraft.

Although there had been prior detections of X-rays from Jupiter with other X-ray telescopes, no one expected that the sources of the X-rays would be located so near the poles. The X-rays are thought to be produced by energetic oxygen and sulfur ions that are trapped in Jupiter’s magnetic field and crash into its atmosphere. Before Chandra’s observations, the favored theory held that the ions were mostly coming from regions close to the orbit of Jupiter’s moon, Io.

Chandra’s ability to pinpoint the source of the X-rays has cast serious doubt on this model. Ions coming from near Io’s orbit cannot reach the observed high latitudes. The energetic ions responsible for the X-rays must come from much further away than previously believed.

One possibility is that particles flowing out from the Sun are captured in the outer regions of Jupiter’s magnetic field, then accelerated and directed toward its magnetic pole. Once captured, the ions would bounce back and forth in the magnetic field, from Jupiter’s north pole to south pole in an oscillating motion that could explain the pulsations.

Original Source: Chandra News Release

NASA Tries to Contact Pioneer 10

Image credit: NASA

Later this week, NASA scientists will attempt to contact the distant Pioneer 10 spacecraft, which was launched 30 years ago. The team will try to reach the spacecraft by focussing a radio telescope at the Jet Propulsion Laboratory?s Deep Space Network (DSN) in Madrid, Spain. Launched on March 2, 1972, Pioneer 10 is now 11.9 billion kilometres away from the Earth and hasn’t been heard from since April 2001.

NASA scientists will try to contact Pioneer 10 this week to see if the plucky little spacecraft?s signal can still be heard ? 30 years after its launch.

On March 2, 2002, scientists operating a radio telescope at the Jet Propulsion Laboratory?s Deep Space Network (DSN) in Madrid, Spain, will attempt to duplicate the feat they accomplished last spring, when they successfully established contact with the spacecraft after a silence of eight months.

“We?re going to try again this year to see if Pioneer 10 still lives on,” said Pioneer 10 Flight Director David Lozier of NASA Ames Research Center, located in the heart of California?s Silicon Valley. “We are hopeful that the successful contacts with the spacecraft that we had last year will be repeated this year.”

NASA made contact with the spacecraft in April of last year. It was the first time the spacecraft had been heard from since the previous summer.

“We had been listening for the Pioneer 10 signal with no success,” recalled Pioneer 10 Project Manager Dr. Larry Lasher of Ames. “So we felt that in order for Pioneer 10 to talk to us, we might need to talk to it.

“We sent up a signal on April 27, 2001, and on April 28, 2001 – 22 hours later, the time it took for the two-way signal to return ? there it was, right on time; it came in loud and clear and strong,” said Lasher. Since then, the scientists have successfully contacted the spacecraft twice more, most recently on July 9, 2001.

Launched on March 2, 1972, Pioneer 10, built by TRW Inc., Redondo Beach, Calif., is now at a distance of 7.4 billion miles from Earth. Pioneer 10 was the first spacecraft to pass through the asteroid belt and the first to make direct observations and obtain close-up images of Jupiter. During the passage by Jupiter, Pioneer 10 also charted Jupiter?s intense radiation belts, located the planet?s magnetic field, and established that Jupiter is predominantly a liquid planet.

In 1983, it became the first man-made object to leave the solar system when it passed the orbit of the most distant planet. The spacecraft continued to make valuable scientific investigations in the outer regions of the solar system until its science mission ended on March 31, 1997. Pioneer 10?s weak signal continues to be tracked by DSN as part of an advanced concept study of communications technology. Pioneer 10 is headed toward the constellation Taurus (the Bull), where it will pass the nearest star in the constellation in about two million years.

“Pioneer 10 has performed much better than expected,” said Robert Hogan, chief of Ames? Space Projects Division where the Pioneer project is managed. “It?s amazing that it?s lasted this long,” added Hogan, who is also a member of the original launch team for the spacecraft.

Scientists continue to analyze data received from Pioneer 10?s Geiger-Tube Telescope instrument operated by principal investigator Dr. James Van Allen of the University of Iowa. Based on the data received, Van Allen concluded that cosmic-ray intensity has continued to decrease. According to Van Allen, Pioneer 10 is still under the delayed influence of solar activity and has not yet reached the cosmic ray modulation boundary of the heliosphere. Scientists say knowledge of this boundary will help define the edge of the solar system, the location where the outermost boundary of the solar system meets interstellar space.

Original Source: NASA News Release

Ariane 5 Rolled out to Launch Pad

An Ariane 5 rocket carrying the European Space Agency’s Envisat satellite, Europe’s largest and most expensive satellite was rolled out to the launch pad yesterday. If all goes well, the rocket will launch Friday morning at 0107 GMT (8:07 EST Thursday night) from Kourou, the European spaceport in French Guiana and carry the 8,000 kg satellite into orbit. Envisat will spend the next 5 years monitoring the health of the Earth’s oceans, ice caps, land and environment.

Brightest Full Moon this Year

Image credit: NASA
The full moon on February 27 is going to be the brightest one of 2002. The moon’s orbit isn’t a perfect circle; over the course of its 28-day trip around the Earth, its distance varies from 406,700 km to 356,400. And today’s full moon happens to coincide with the closest point of that orbit, making it 20% brighter than an average full moon.

A pale ray of light shines through the bedroom window. In the distance, something howls. Eyes open. The clock ticks, it’s 2 a.m.. You’re wide awake — roused by a bright full Moon.

Don’t be surprised if this soon happens to you. The Moon will become full on Feb. 27th. It happens every 29.5 days, yet this full Moon is special: It’s the biggest and brightest of the year.

“Not all full Moons are alike,” says astronomy professor George Lebo. “Sometimes pollution or volcanic ash shades them with interesting colors. Sometimes haloes form around them — a result of ice crystals in the air.”

“This full Moon is unique in another way,” he says. “It will be closer to Earth than usual.”

Right: The apparent size of the Moon at perigee (top) and apogee (bottom).

“The moon’s orbit around our planet is not a perfect circle,” Lebo explains. “It’s an ellipse.” At one end of the ellipse (called apogee) the Moon lies 406,700 km from Earth. At the other end (called perigee) the Moon is only 356,400 km away — a difference of 50 thousand km!

When the Moon is full on Feb. 27th it will be near perigee — close to Earth. As a result the Moon will appear 9% wider than normal and shine 20% brighter.

The extra moonlight is caused, in part, by the Moon’s nearness to Earth. But that’s not all. The Sun is closer to Earth, too. Lebo explains: “Every year during northern winter, Earth is about 1.6% closer to the Sun than normal. (Like the Moon’s orbit around Earth, Earth’s orbit around the Sun is elliptical. Our closest approach to the Sun is called perihelion.) The Moon reflects sunlight, so the Moon is brighter during that time.”

This effect should not to be confused with the famous “Moon Illusion” — a trick of the eye that makes Moons rising near the horizon appear swollen. The nearby full Moon this week really will be bigger and brighter.

Below: The brightness of full Moons in 2002 relative to that of an average full Moon. In Feb., for example, the Moon will be 20% brighter than average; in Aug. it will be 12% dimmer. These values take into account the varying distances of the Moon from Earth and of the Earth from the Sun.

The first three full Moons of 2002 are all brighter-than-average. All three happen when the Moon is near perigee, and when Earth is relatively close to the Sun. Full Moons later this year will be smaller and dimmer by comparison. For example, August’s full Moon — an “apogee Moon” — will be about one-third dimmer than February’s.

But will anyone notice the difference?

“The human eye can easily discern a 20 or 30% difference in the brightness of two similar light sources,” says eye doctor Stuart Hiroyasu. By that reckoning, a sky watcher could tell the difference between a bright perigee Moon and a dimmer apogee Moon. But the two Moons would have to be side by side to effect the comparison — not likely except in a science fiction movie!

Below: Our Moon’s appearance changes nightly. This time-lapse sequence (Credit: Ant?nio Cidad?o) shows what our Moon looks like during a lunation, a complete lunar cycle. [more]

Even the dimmest full Moons are very bright, notes Lebo. They outshine Sirius, the brightest star in the sky, by twenty-five thousand times. They cast shadows, and provide enough light to read by. “There’s really no such thing as a faint full Moon. It’s all relative.”

Nevertheless, some sky watchers will sense that this Moon has something “extra” — particularly northerners. Many northern landscapes in February remain covered with snow. Snow reflects about two-thirds of the light that hits it, while bare ground reflects only about 15%. A snowy moonlit landscape always seems remarkably bright.

Perigee, perihelion, snowy terrain — they all add up to a big dose of Moonlight. Can you tell the difference? There’s only one way to find out: Go outside and look!

Original Source: NASA Science Story

Cold Weather Delays Shuttle Launch

Unusually cold weather in Florida has forced NASA to push back Thursday’s launch of the space shuttle Columbia for its service mission to the Hubble Space Telescope. Officials are predicting temperatures only a few degrees above freezing, but significantly warmer on Friday (cold weather was a contributing factor to the Challenger disaster). During the 11-day flight, astronauts will add $172 million in upgrades to Hubble. (AP article)

Quikscat Satellite Goes Operational

Weather forecasters have added wind speed and direction data from NASA’s Quick Scatterometer spacecraft (Quikscat) to help them predict violent storms as much as 6-12 hours before they happen. Launched almost three years ago, the Quikscat takes approximately 400,000 measurements every day, comprising 93% of the Earth’s surface. The spacecraft has proven its ability to improve forecasts of hurricanes, so several International weather agencies have decided to assimilate its data into their predictions.

In a move to improve global weather forecasts and ultimately save lives and property, the United States and Europe have incorporated wind speed and direction data from NASA’s Quick Scatterometer spacecraft-also known as Quikscat-into their operational global weather analysis and forecast systems.

Armed with data from Quikscat, forecasters can now predict hazardous weather events over the oceans as much as six to 12 hours earlier. Launched June 19, 1999, the Quikscat spacecraft operates in a Sun-synchronous, 800-kilometer (497-mile) near-polar orbit, circling Earth every 100 minutes, taking approximately 400,000 measurements over 93 percent of Earth’s surface every day.

In recent years, data from the Quikscat scatterometer, developed by NASA’s Jet Propulsion Laboratory, Pasadena, Calif., have proven useful in improving forecasts of extreme wind events, such as hurricanes, and in monitoring longer-term climatic effects such as El Nino. Quikscat’s SeaWinds scatterometer instrument is a specialized microwave radar that continuously measures both the speed and direction of winds near the ocean surface in all weather conditions.

Participants in the Quikscat program include the National Centers for Environmental Prediction, a branch of the National Weather Service, Washington, D.C., and the European Centre for Medium-Range Weather Forecasts, Reading, England. These organizations’ decision to assimilate and turn Quikscat data into operational information culminates an intense inter-agency and international cooperative effort among NASA, the National Oceanic and Atmospheric Administration (NOAA) and European countries to demonstrate and validate Quikscat’s potential impact on weather forecasting.

“Our implementation of Quikscat data has provided another useful data source for improved surface wind forecasts,” said Stephen Lord, director of the National Centers for Environmental Prediction’s Environmental Modeling Center, which developed the Quikscat data processing in collaboration with NASA and NOAA Satellite Service.

“The use of Quikscat data to improve weather forecasts underscores the value of the mission beyond the scientific research community,” said Dr. Michael Freilich, Quikscat principal investigator and a professor at Oregon State University, Corvallis. “Realizing the full potential of Quikscat data is possible only because of a series of unique collaborations. NASA researchers and engineers worked together to develop and calibrate the instrument and algorithms. NOAA personnel, in partnership with NASA, enable rapid delivery of near-real-time spacecraft data to forecast centers. There also are the teams of meteorologists who are developing and refining computer programs that incorporate the data into models and display measurements for forecasters.”

Helen Wood, director of NOAA’s Office of Satellite Data Processing and Distribution, said Quikscat data would positively impact NOAA’s weather forecasting and storm warnings. “Quikscat data will help our forecasters more accurately determine the paths and intensities of severe winter storms, tropical storms and hurricanes, which saves lives and property,” she said. “The data are also used by climate change researchers and commercial shipping interests.”

The incorporation of Quikscat data was one of several recent upgrades made to the European Centre for Medium-Range Weather Forecasts’ operational system. Cumulatively, the upgrades have resulted in a robust improvement in forecasts of atmospheric conditions over the Southern Hemisphere and in the upper atmosphere. Their ability to forecast tropical cyclone tracks has also been enhanced.

JPL manages Quikscat for NASA’s Office of Earth Science, Washington, D.C. JPL also built the scatterometer instrument and provides ground science processing systems. NASA’s Goddard Space Flight Center, Greenbelt, Md., managed development of the satellite, designed and built by Ball Aerospace & Technologies Corp., Boulder, Colo.

Original Source: NASA News Release

Ariane Rocket Places Intelsat Bird into Orbit

An Ariane 44L rocket lifted off from Kourou, French Guiana on Saturday at 0659 GMT (1:59am EST), carrying an Intelsat 904 communications satellite into orbit. The Intelsat satellite will provide video and data services for Asia, Africa and Europe. This was the second launch for Arianespace this year; an Ariane 5 is scheduled to launch on February 28.

Columbia Countdown Begins

NASA began the countdown on Monday for the upcoming launch the space shuttle Columbia on a mission to upgrade the Hubble Space Telescope. If all goes well, Columbia will lift off from the Kennedy Space Center on February 28 at 1148 GMT (6:48am EST). Over the course of the 11-day mission, astronauts will carry out five scheduled spacewalks to install new hardware, including a new camera, solar wings, a power-control unit, and steering mechanism. Forecasters are expecting a 70% chance that the weather will be good enough for launch.

Bow Shock in a Merging Galactic Cluster

A new image taken by the Chandra X-Ray observatory reveals a bow-shaped shock wave towards one side of an extremely hot galactic cluster. Astronomers believe that the shock wave is caused by 70 million degree Celsius gas is ploughed through the cluster at a speed of 10 million kph. This cluster is of great interest to astronomers because it’s one of the hottest clusters ever found – astronomers think that the galaxy might have gotten so hot because it absorbed many smaller clusters in the past.