A pair of NASA spacecraft that were supposed to be dead a year ago are instead flying to the Moon for a breakthrough mission in lunar orbit.

"Their real names are THEMIS P1 and P2, but I call them 'dead spacecraft walking,'" says Vassilis Angelopoulos of UCLA, principal investigator of the THEMIS mission. "Not so long ago, we thought they were goners. Now they are beginning a whole new adventure."

An artist's concept of THEMIS-P1 and P2 (since renamed ARTEMIS-P1 and P2) in lunar orbit. [larger image]

The story begins in 2007 when NASA launched a fleet of five spacecraft into Earth's magnetosphere to study the physics of geomagnetic storms. Collectively, they were called THEMIS, short for "Time History of Events and Macroscale Interactions during Substorms." P1 and P2 were the outermost members of the quintet.

Working together, the probes quickly discovered a cornucopia of previously unknown phenomena such as colliding auroras, magnetic spacequakes, and plasma bullets shooting up and down Earth’s magnetic tail. These findings allowed researchers to solve several longstanding mysteries of the Northern Lights.

In their previous life, THEMIS-P1 and P2 were on a mission to study Northern Lights. [more]

The mission was going splendidly, except for one thing: Occasionally, P1 and P2 would pass through the shadow of Earth. The solar powered spacecraft were designed to go without sunlight for as much as three hours at a time, so a small amount of shadowing was no problem. But as the mission wore on, their orbits evolved and by 2009 the pair was spending as much as 8 hours a day in the dark.

"The two spacecraft were running out of power and freezing to death," says Angelopoulos. "We had to do something to save them."

The team brainstormed a solution. Because the mission had gone so well, the spacecraft still had an ample supply of fuel--enough to go to the Moon. "We could do some great science from lunar orbit," he says. NASA approved the trip and in late 2009, P1 and P2 headed away from the shadows of Earth.

With a new destination, the mission needed a new name. The team selected ARTEMIS, the Greek goddess of the Moon. It also stands for "Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun."

The first big events of the ARTEMIS mission are underway now. On August 25, 2010, ARTEMIS-P1 reached the L2 Lagrange point on the far side of the Moon. Following close behind, ARTEMIS-P2 entered the opposite L1 Lagrange point on Oct. 22nd. Lagrange points are places where the gravity of Earth and Moon balance, creating a sort of gravitational parking spot for spacecraft.

The ARTEMIS spacecraft are currently located at the L1 and L2 Earth-Moon Lagrange points. [more]

"We're exploring the Earth-Moon Lagrange points for the first time," says Manfred Bester, Mission Operations Manager from the University of California at Berkeley, where the mission is operated. "No other spacecraft have orbited there."

Because they lie just outside Earth's magnetosphere, Lagrange points are excellent places to study the solar wind. Sensors onboard the ARTEMIS probes will have in situ access to solar wind streams and storm clouds as they approach our planet—a possible boon to space weather forecasters. Moreover, working from opposite Lagrange points, the two spacecraft will be able to measure solar wind turbulence on scales never sampled by previous missions.

"ARTEMIS is going to give us a fundamental new understanding of the solar wind," predicts David Sibeck, ARTEMIS project scientist at the Goddard Space Flight Center. "And that's just for starters."

ARTEMIS will also explore the Moon's plasma wake—a turbulent cavity carved out of the solar wind by the Moon itself, akin to the wake just behind a speedboat. Sibeck says "this is a giant natural laboratory filled with a whole zoo of plasma waves waiting to be discovered and studied."

A Youtube video describes the complex orbits of the two Artemis spacecraft.

Another target of the ARTEMIS mission is Earth's magnetotail. Like a wind sock at a breezy airport, Earth's magnetic field is elongated by the action of the solar wind, forming a tail that stretches to the orbit of the Moon and beyond. Once a month around the time of the full Moon, the ARTEMIS probes will follow the Moon through the magnetotail for in situ observations.

"We are particularly hoping to catch some magnetic reconnection events," says Sibeck. "These are explosions in Earth's magnetotail that mimic solar flares--albeit on a much smaller scale." ARTEMIS might even see giant 'plasmoids' accelerated by the explosions hitting the Moon during magnetic storms.

These far-out explorations may have down-to-Earth applications. Plasma waves and reconnection events pop up on Earth, e.g., in experimental fusion chambers. Fundamental discoveries by ARTEMIS could help advance research in the area of clean renewable energy.

After six months at the Lagrange points, ARTEMIS will move in closer to the Moon—at first only 100 km from the surface and eventually even less than that. From point-blank range, the spacecraft will look to see what the solar wind does to a rocky world when there's no magnetic field to protect it.

"Earth is protected from solar wind by the planetary magnetic field," explains Angelopolous. "The Moon, on the other hand, is utterly exposed. It has no global magnetism."

Studying how the solar wind electrifies, alters and erodes the Moon's surface could reveal valuable information for future explorers and give planetary scientists a hint of what's happening on other unmagnetized worlds around the solar system.

Orbiting the Moon is notoriously tricky, however, because of irregularities in the lunar gravitational field. Enormous concentrations of mass (mascons) hiding just below the surface tug on spacecraft in unexpected ways, causing them over time to veer out of orbit. ARTEMIS will mitigate this problem using highly elongated orbits ranging from tens of km to 18,000 km.

"We'll only be near the lunar surface for a brief time each orbit (accumulating a sizable dataset over the years)," explains Angelopoulos. "Most of the time we'll linger 18,000 km away where we can continue our studies of the solar wind at a safe distance."

The Dead Spacecraft Walking may have a long life, after all.

Author: Dr. Tony Phillips | Credit: Science@NASA

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Chandrayaan-1, India’s first unmanned spacecraft mission to moon, entered lunar orbit today (November 8, 2008). This is the first time that an Indian built spacecraft has broken away from the Earth’s gravitational field and reached the moon. This historic event occurred following the firing of Chandrayaan-1 spacecraft’s liquid engine at 16:51 IST for a duration of 817 seconds. The highly complex ‘lunar orbit insertion manoeuvre’ was performed from Chandrayaan-1 Spacecraft Control Centre of ISRO Telemetry, Tracking and Command Network at Bangalore.

Indian Deep Space Network (IDSN) at Byalalu supported the crucial task of transmitting commands and continuously monitoring this vital event with two dish antennas, one measuring 18 m and the other 32 m.

Chandrayaan-1’s liquid engine was fired when the spacecraft passed at a distance of about 500 km from the moon to reduce its velocity to enable lunar gravity to capture it into an orbit around the moon. The spacecraft is now orbiting the moon in an elliptical orbit that passes over the polar regions of the moon. The nearest point of this orbit (periselene) lies at a distance of about 504 km from the moon’s surface while the farthest point (aposelene) lies at about 7502 km. Chandrayaan-1 takes about 11 hours to go round the moon once in this orbit.

The performance of all the systems onboard Chandrayaan-1 is normal. In the coming days, the height of Chandrayaan-1 spacecraft’s orbit around the moon will be carefully reduced in steps to achieve a final polar orbit of about 100 km height from the moon’s surface. Following this, the Moon Impact Probe (MIP) of the spacecraft will be released to hit the lunar surface. Later, the other scientific instruments will be turned ON sequentially leading to the normal phase of the mission.

It may be recalled that Chandrayaan-1 spacecraft was launched on October 22, 2008 by PSLV-C11 from India’s spaceport at Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota. As intended, PSLV placed the spacecraft in a highly oval shaped orbit with a perigee (nearest point to Earth) of 255 km and an apogee (farthest point to Earth) of 22,860 km. In the past two weeks, the liquid engine of Chandrayaan-1 has been successfully fired five times at opportune moments to increase the apogee height, first to 37,900 km, then to 74,715 km, later to 164,600 km, after that to 267,000 km and finally to 380,000km, as planned. During this period, the Terrain Mapping Camera (TMC), one of the eleven payloads (scientific instruments) of the spacecraft, was successfully operated twice to take the pictures, first of the Earth, and then moon.

With today’s successful manoeuvre, India becomes the fifth country to send a spacecraft to Moon. The other countries, which have sent spacecraft to Moon, are the United States, former Soviet Union, Japan and China. Besides, the European Space Agency (ESA), a consortium of 17 countries, has also sent a spacecraft to moon. Read more!

Chandrayaan-1 spacecraft has entered deep space after crossing the 150,000 km (one and a half lakh km) distance mark from the Earth. This happened after the successful completion of the spacecraft’s third orbit raising manoeuvre today (October 26, 2008) morning.

During this manoeuvre which was initiated at 07:08 IST, the spacecraft’s 440 Newton liquid engine was fired for about nine and a half minutes. With this, Chandrayaan-1 entered a much higher elliptical orbit around the Earth. The apogee (farthest point to Earth) of this orbit lies at 164,600 km while the perigee (nearest point to Earth) is at 348 km. In this orbit, Chandrayaan-1 takes about 73 hours to go round the Earth once.

The antennas of the Indian Deep Space Network at Byalalu are playing a crucial role in tracking and communicating with Chandrayaan-1 spacecraft in such a high orbit. The spacecraft performance is normal. More orbit raising manoeuvres are planned in the coming few days to take Chandrayaan-1 towards the Moon.

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On 56th indepence day, August 15 2003, India's Prime Minister Atal Bihari Vajpayee announced. "Our country is now ready to fly high in the field of science. I am pleased to announce that India will send her own spacecraft to the moon by 2008. It is being named Chandrayaan-1". In Sanskrit (language of Ancient India) "Chandrayaan" means "Moon Craft".

Moon has always fascinated Indians from ancient days and now 21st century india is ready to land on moon! Chandrayaan-1 is the first mission towords the dream.

In Chandrayaan-1, the lunar craft would be launched using Polar Satellite Launch Vehicle (PSLV) weighing 1304 kg at launch and 590 kg at lunar orbit. Lunar craft would orbit around moon 100 km from moon surface.

ISRO inviated international space orgnization to particpate in the project by providing suitable scientific payloads(instrument for experiments). ISRO selected
3 (C1XS, SIR-2, SARA) payload from ESA (European Space Agency)
1 (RADOM) from BSA (Bulgarian Academy of Science),
2 (MiniSAR, M3) from NASA (National Aeronautics and Space Administration)

http://www.chandrayaan-i.com/chandrayaan1/index1.html







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The country is about to begin its campaign to conquer the moon, setting the tone for its role in a future global effort to colonise earth’s natural satellite. Nirad Mudur reports from Bangalore

On October 22, the Chandrayaan-1 spacecraft is expected to blast off from Sriharikota and aim for the moon, making India join an elite club of a handful of nations to have tried sojourning at the earth’s natural satellite.

Just days ago, action stations at the Indian Space Research Organisation (Isro) moved
Chandrayaan-1 from the Isro Space Applications Centre (Isac) in Bangalore to the Satish Dhawan Space Centre (SDSC) at Sriharikota, about 80km north of Chennai. The spacecraft will orbit the moon for two years at an altitude of 100km before Isro’s scientists will intentionally crash it into the moon’s surface.

Some critics have suggested India is merely reinventing the wheel since the Americans and the Soviets have already done substantial work on the moon, not to speak of their numerous manned moon missions: between 1958 and 1976, the two superpowers carried out 69 unmanned and manned moon missions; the six successful US manned missions, starting with Apollo 11, between 1969 and 1972, and the three USSR missions between 1970 and 1976 were applauded the world over. Contrast this with Isro scientists saying that India is still not equipped to send its own ‘vyomanauts’ (‘vyom’ is ‘space’ in Sanskrit) to the moon.

India may be late, but it has an agenda. “Till now, moon missions have been in localised spaces,” says M Annadurai, mission director, Chandrayaan-1. “But we are planning to cover the entire moon, both sides of it — the one which faces the earth and the one which faces away.” (You may recall from your school science class that the moon rotates around its axis and revolves around the earth in roughly the same time: 28 days. Therefore, one side of the moon always faces the earth while the other always remains hidden.) Read more!

A team of internationally renowned astronomers and opticians may have found a way to make "unbelievably large" telescopes on the Moon.

"It's so simple," says Ermanno F. Borra, physics professor at the Optics Laboratory of Laval University in Quebec, Canada. "Isaac Newton knew that any liquid, if put into a shallow container and set spinning, naturally assumes a parabolic shape—the same shape needed by a telescope mirror to bring starlight to a focus. This could be the key to making a giant lunar observatory."

Borra, who has been studying liquid-mirror telescopes since 1992, and Simon P. "Pete" Worden, now director of NASA Ames Research Center, are members of a team taking the idea for a spin.

Right: An artist's concept of a spinning liquid mirror telescope on the Moon. Credit: Univ. of British Columbia.

On Earth, a liquid mirror can be made quite smooth and perfect if it its container is kept exactly horizontal and rests on a low-vibration low-friction air bearing that is spun by a synchronous motor having one stable speed. "It doesn't need to spin very fast," says Borra. "The rim of a 4-meter–diameter mirror—the largest I've made in my lab—travels only 3 miles per hour, about the speed of a brisk walk. In the low gravity of the Moon, it would spin even slower."

Most liquid-mirror telescopes on Earth have used mercury. Mercury remains molten at room temperature, and it reflects about 75 percent of incoming light, almost as good as silver. The biggest liquid-mirror telescope on Earth, the Large Zenith Telescope operated by the University of British Columbia in Canada, is 6 meters across—a diameter 20 percent larger than the famous 200-inch mirror of the Hale telescope at Palomar Observatory in California. Yet when completed in 2005, the Canadian Palomar-class liquid-mirror telescope cost less than $1 million to build—only a few percent the cost of a solid-mirror telescope of the same diameter--and, for that matter, only a sixth of Palomar's original cost in 1948.

Those economics are making astronomers sit up and begin noodling out plans for a lunar observatory.

"Our study [with Borra] started when I was still an astronomy professor at the University of Arizona before I came to NASA in 2006," Worden recalls. "The real appeal of this approach is that we could get an unbelievably large telescope on the Moon."

Mercury is unworkable on the Moon: it's very dense and thus heavy to launch, it's very expensive, and it would evaporate quickly when exposed to the lunar vacuum. In recent years, however, Borra and his colleagues have been experimenting with a class of organic compounds known as ionic liquids. "Ionic liquids are basically molten salts," Borra explains. "Their evaporation rate is almost zero, so they would not vaporize in the lunar vacuum. They can also remain liquid at very low temperatures." He and his colleagues are now seeking to synthesize ionic liquids that remain molten even at liquid-nitrogen temperatures.

Below: The University of British Columbia's 6-meter Large Zenith Telescope uses a liquid mirror to scan the heavens. [more]

Much less dense than mercury, ionic liquids are only slightly denser than water. Although not highly reflective themselves, a spinning mirror of an ionic liquid can be coated with an ultrathin layer of silver just as if it were a solid mirror. Weirdest of all, the silver layer is so thin—only 50 to 100 nanometers—that it actually solidifies. In the vacuum of space, a liquid mirror coated with a thin solid layer of silver would neither evaporate nor tarnish.

A liquid mirror can't be tilted away from the horizontal because the fluid would pour out, destroying the mirror. But that does not mean a liquid mirror telescope cannot be pointed. Optical designers are now experimenting with ways of electromechanically warping secondary mirrors suspended above a liquid mirror—or even slightly warping the liquid mirror itself—to aim at angles away from the vertical. Similar techniques are used to point the great Arecibo radio telescope in Puerto Rico.

Furthermore, says Borra, "if the telescope is located anywhere other than exactly at the poles, with each rotation of Earth or Moon it would scan a circular strip of sky. And the rotational axis of the Moon wobbles with a period of 18.6 years; so over a period of 18.6 years, the telescope would actually look at a good-sized region of the sky."

Right: The 1000-ft Arecibo radio telescope in Puerto Rico cannot be moved, but it can still scan a wide swath of sky using movable secondary mirrors. A lunar liquid mirror telescope might employ similar techniques. [more]

Locating a major liquid-mirror telescope near the lunar poles is appealing. The telescope itself could reside near the bottom of a permanently shadowed crater where it would stay at cryogenic temperatures, desirable for the best infrared astronomy. Yet solar panels could be erected on nearby permanently illuminated mountain peaks to generate power to keep the mirror spinning.

The fact that a liquid-mirror telescope always looks straight up vastly simplifies its construction and reduces mass by eliminating heavy mounts, gearing, and pointing-control systems needed for a steerable telescope. "All you'd need is the liquid-mirror container, which might be an umbrella-like device that self-deploys, plus a nearly frictionless superconducting bearing and its drive motor," Borra says. Worden estimates that all the materials for an entire lunar telescope 20 meters across would be "only a few tons, which could be boosted to the Moon in a single Ares 5 mission in the 2020s." Future telescopes might have mirrors as large as 100 meters in diameter—larger than a football field.

"A mirror that large could peer back in time to when the universe was very young, only half a billion years old, when the first generation of stars and galaxies were forming," Borra exclaimed. "Potentially more exciting is pure serendipity: new things we might discover that we just don't expect."

Says Worden: "Putting a giant telescope on the Moon has always been an idea of science fiction, but it soon could become fact."

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