ESA Rosetta: NASA instruments on comet spacecraft begin activation countdown

This artist's impression shows the Rosetta orbiter at comet 67P/Churyumov-Gerasimenko. 

Credit: ESA /ATG Medialab

Three NASA science instruments are being prepared for check-out operations aboard the European Space Agency's Rosetta spacecraft, which is set to become the first to orbit a comet and land a probe on its nucleus in November.

Rosetta was reactivated Jan. 20 after a record 957 days in hibernation. U.S. mission managers are scheduled to activate their instruments on the spacecraft in early March and begin science operations with them in August.

The instruments are an ultraviolet imaging spectrograph, a microwave thermometer and a plasma analyzer.

Claudia Alexander

"U.S. scientists are delighted the Rosetta mission gives us a chance to examine a comet in a way we've never seen one before—in orbit around it and as it kicks up in activity," said Claudia Alexander, Rosetta's U.S. project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

"The NASA suite of instruments will provide puzzle pieces the Rosetta science team as a whole will put together with the other pieces to paint a portrait of how a comet works and what it's made of."

Rosetta's objective is to observe the comet 67P/Churyumov-Gerasimenko up close. By examining the full composition of the comet's nucleus, and the ways in which a comet changes, Rosetta will help scientists learn more about the origin and evolution of our solar system and the role comets may have played in seeding Earth with water, and perhaps even life.

The ultraviolet imaging spectrograph, called Alice, will analyze gases in the tail of the comet, as well as the coma, the fuzzy envelope around the nucleus of the comet.

The coma develops as a comet approaches the Sun.

Alice also will measure the rate at which the comet produces water, carbon monoxide and carbon dioxide.

These measurements will provide valuable information about the surface composition of the nucleus.

The instrument also will measure the amount of argon present, an important clue about the temperature of the solar system at the time the comet's nucleus originally formed more than 4.6 billion years ago.

The Microwave Instrument for Rosetta Orbiter (MIRO)will identify chemicals on or near the comet's surface and measure the temperature of the chemicals and the dust and ice jetting out from the comet.

The instrument also will see the gaseous activity in the tail through coma.

The Ion and Electron Sensor is part of a suite of five instruments to analyze the plasma environment of the comet, particularly the coma.

The instrument will measure the charged particles in the Sun's outer atmosphere, or solar wind, as they interact with the gas flowing out from the comet while Rosetta is drawing nearer to the comet's nucleus.

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ESA Launch preparations begin for Gaia galaxy-mapper

Artist's concept of the Gaia spacecraft. 

Credit: ESA/ ATG medialab; background image: ESO/S. Brunier

Europe’s new eye on the galaxy arrived in French Guiana on Friday, beginning three months of flight preparations before liftoff on a Soyuz rocket in November to commence a survey of a billion stars and chart their chaotic motion in the Milky Way galaxy.

The Gaia observatory will be stationed a million miles from Earth, its dual telescopes sweeping across the sky with the sensitivity to plot the exact locations and movements of stars, detect the signatures of alien worlds, and spot icy dwarf planets on the outer frontier of the solar system.

The breadth of Gaia’s scientific promise ranges from scanning the Milky Way to create a three-dimensional map of the galaxy to the discovery of asteroids in Earth's neighborhood.

Scientists say Gaia could return data leading to the discovery of up to 2,000 planets around other stars – mostly Jupiter-sized gas giants.

And the European space mission has the precision to test tenets of Albert Einstein’s theory of general relativity by observing how the pull of the sun and planets bend starlight before it reaches Gaia’s apertures.

In five years, Gaia will collect a petabyte of data, enough to fill 1.5 million compact discs. It will see a billion stars, more than ever observed by any other mission, and use information about those objects to study the origin and evolution of the Milky Way.

“The estimate of the number of stars in the Milky Way is between 100 and 200 billion stars, so we observe between one-half and one percent of these stars,” said Timo Prusti, Gaia’s project scientist at the European Space Agency.

“Because of the completeness of Gaia to a limiting magnitude, this proving of 1 percent of these objects will help us reconstruct the remaining part. We’re not going to take a full census of the Milky Way, but we are going to look at a billion stars and we’ll have enough statistical power to deduce the structure of the Milky Way.”

A team of scientists and engineers has worked on Gaia since the mission was approved by the European Space Agency in 2000. The mission’s cost is 740 million euros, or approximately $990 million.

After of 13 years of development, design reviews, construction and testing, Gaia is one step closer to the launch pad.

Liftoff is scheduled for Nov. 20 at 0857 GMT (3:57 a.m. EST; 5:57 a.m. local time) aboard a Europeanized version of Russia’s Soyuz rocket.

The mission will mark the seventh flight of a Soyuz booster from French Guiana, and a Fregat upper stage will propel Gaia on a trajectory toward the L2 Lagrange point about a million miles from the night side of Earth, where gravity from the Earth and sun balance a satellite’s motion.

ESA Ariane-5 Launch preparations: Mission ATV - Albert Einstein

Ariane 5’s cryogenic core stage is suspended over the launch table in the Spaceport’s Launcher Integration Building. Credits: ESA/CNES/Arianespace/Optique Video du CSG

The launcher for Arianespace’s fourth flight with Automated Transfer Vehicle 4 (ATV-4), Albert Einstein, is rapidly taking shape at the Spaceport, preparing it for liftoff in the spring from French Guiana with the International Space Station’s latest resupply spacecraft.

During activity this month in the Spaceport’s Launcher Integration Building, the heavy-lift vehicle’s core cryogenic stage was suspended over the mobile launch table, followed by positioning of its two solid propellant boosters.

The launcher’s EPS storable propellant upper stage will then be installed, readying the Ariane 5 for transfer to the Final Assembly Building, where the latest ATV (named after Albert Einstein) is to be mated.