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Valentine’s Day date with a comet

Close-up view of comet Tempel 1

Pancake-layers and a possible powdery flow are among the surface features of interest highlighted in this July 4, 2005, Deep Impact image of Comet Tempel 1. The bright flash is where Deep Impact dropped a 1.8-tonne copper projectile onto the comet. Stardust-NExT could get a first look at the aftermath of the blast.

  • Stardust-NExT spacecraft to conduct fly-by of comet Tempel 1
  • Second comet fly-by for Stardust, and second spacecraft encounter for Tempel 1
  • Aim is to see changes in Tempel 1 since Deep Impact’s visit in 2005

BOTH COUPLES SEEMED meant for each other. There was the Stardust spacecraft, launched in 1999, and her cometary fiancée, Wild 2. Betrothed from afar, the two headed blissfully toward a 2004 rendezvous.

Meanwhile, the comet Tempel 1, making her own solitary way around the Sun in 2005, was heading toward a more explosive relationship with the Deep Impact spacecraft.

But alas, heavenly though the matches were—and fruitful, with each yielding valuable information about the evolution of the solar system—neither lasted. In 2006, Stardust tossed her dusty tokens of Wild 2 down to Earth for analysis and vowed to start anew.

She was a little older now; but with all her parts in good working order and adequate fuel, she was ready for a second mission. And Tempel 1, scarred by her violent encounter with Deep Impact, was looking for a kinder, gentler match.

Geometry of Stardust-NExT's Tempel 1 encounter

The Stardust spacecraft will pass within 200 kilometres of comet Tempel 1 on Feb 14 (US time)—close enough to provide a first look at the crater caused by the Deep Impact collision (bull's eye) and a large piece of previously unmapped territory (blue).

On Valentine’s Day, the two will meet. In the heat of the moment, astronomers hope, Tempel 1 will be cajoled into yielding a few more clues about her background. And Stardust, equipped with imaging and dust composition analysis instruments, will relay those clues to Earth.

Expectant matchmakers

Among the astronomers waiting patiently are Joe Veverka, professor of astronomy and principal investigator for Stardust-NExT, the NASA mission orchestrating the rendezvous.

The Valentine’s Day flyby could yield a wealth of new information about Tempel 1’s structure and composition, Veverka said, and how its features change with every passage around the Sun.

“We know that comets lose material,” he said in a recent press conference. “But the question is, ‘How does the surface change, and where does the surface change?’” Comparing the 2005 images with the new ones—taken one rotation around the Sun later—could provide the answer.

Stardust could also catch a glimpse of the crater that formed when a probe from Deep Impact crashed into Tempel 1’s surface six years ago.

“That impact threw up so much ejecta that Deep Impact never saw the crater,” Veverka said. “So it could never see how big the crater is and what [it] tells us about the mechanical properties of the surface.”

That information is vital for any future mission that involves landing a spacecraft on the surface of a comet, he said.

And finally, astronomers hope the rendezvous will provide a closer look at some of the surface features Deep Impact saw when it zoomed by in 2005. Layered terrain, for example, could contain information about how comet nuclei were formed; and smooth flows hint at some internal processes that could be working their way up to change the surface.

“Deep Impact saw only about one-third of the surface,” Veverka said. “We would like to see more.”

Stardust-NExT's first glimpse of Tempel 1

Stardust-NExT's first glimpse of Tempel 1, taken on January 18-19, 2011.

So, as February 14 approaches and other romantic souls plan candlelight dinners, Veverka and colleagues are tracking the pair, now hurtling toward each other at about 590,000 miles a day.

Stardust caught its first glimpse of Tempel 1 on January 26. It will keep its eye on the comet as it approaches, collecting data to help mission navigators refine its trajectory.

Close encounter

And on Valentine’s Day, as Earthbound lovers gaze into each other’s eyes, the two orbiting bodies will meet, about 120 miles apart. As they pass, Stardust will test the density and composition of the dust surrounding the comet and snap 72 high-resolution images.

(Note: the fly-by is due to occur at 11:37pm, US EST on February 14, which is 3:37pm February 15 Sydney time.)

Researchers expect to receive the data within a few hours of the closest encounter. “The science team is awfully excited,” Veverka said.

And thus, perhaps, the curtain will close on this cometary encore. But as with all concluded affairs, there will be months—perhaps years—of data analysis; and ultimately, plans for the next mission.

“Comets preserve some of the most faithful information about what happened when the Solar System formed,” Veverka said. “This is a step toward the ultimate answer.”

Follow Stardust-NExT on Twitter

Follow the comet encounter live on NASA TV

Stardust-NExT facts:

Stardust mission: Approved by NASA in 1995 for mission to comet Wild 2

Spacecraft manufacturer: Lockheed-Martin Aeronautics

Launch vehicle: Boeing Delta II rocket

Launch: February 7, 1999 (as Stardust)

Asteroid Anne Frank flyby: November 2, 2002

Comet Wild 2 flyby: January 2, 2004

Sample capsule return: January 15, 2006

July 3, 2007: Stardust approved for NExT mission to comet Tempel 1

Comet Tempel 1 flyby: February 14, 2011

Electrical power: Generated by solar panels

Kilometres travelled: About 5.8 billion

Adapted from information issued by Cornell University / NASA / JPL-Caltech.

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2011: The year in space

Artist's impression of the Juno spacecraft at Jupiter

Artist's impression of the Juno spacecraft investigating Jupiter. Juno is set for launch later this year.

THERE ARE LOTS OF EXCITING happenings coming up in space this year. Here’s just a sample of what we can expect.

On February 14-15, NASA’s Stardust probe will do a fly-by of comet Tempel 1. It’ll be looking for damage done by the Deep Impact spacecraft, which fired a projectile into the comet back in 2005.

Also there’ll be the launch of Glory, an Earth-orbiting spacecraft that’ll make readings of black carbon and aerosols in the atmosphere, and measure the amount of incoming sunlight. Plus there’ll be the final flight of the space shuttle Discovery, on a mission to the space station.

March will see NASA’s MESSENGER spacecraft go into orbit around Mercury, the first probe to do so. A largely unknown world, the closest planet to the Sun is sure to hold some surprises. That month will also mark 25 years since Europe’s Giotto probe gave us our first close-up look at a comet, the famous Halley.

In April there’ll be a bunch of anniversaries, the 30th of the first space shuttle launch, the 40th of the first space station launch (which was the Soviet’s Salyut 1), and the biggie, the 50th anniversary of the flight of Vostok 1, carrying Yuri Gagarin, the first person to go into outer space.

Artist's impression of Salyut 1

Artist's impression of Salyut 1, the world's first space station.

April will also see the last flight of space shuttle Endeavour. And it could be the final shuttle mission of all. An extra flight by Atlantis in June has been approved but not yet funded, so we’ll just have to wait and see. Also in June, some parts of Australia will catch a short glimpse of a lunar eclipse.

July will see the second flight of the new, private Dragon spacecraft, designed to take cargo and eventually people to the International Space Station. Its first short test flight last year went perfectly. Dragon could end up being the replacement for the space shuttle.

Also in July, NASA’s Dawn spacecraft will sidle up to the 530km-wide asteroid Vesta, and go into orbit. It’ll spend a year investigating it before heading off to do the same thing with the even larger asteroid Ceres, which is actually known as a dwarf planet these days.

Artist's impression of the Dawn spacecraft

Artist's impression of the Dawn spacecraft studying asteroid Vesta

August will see the launch of Juno, NASA’s new unmanned mission to study the planet Jupiter. It’ll take about five years to get there. And the following month will see NASA launch GRAIL, a pair of satellites that’ll orbit the Moon and map its gravitational field, which will help scientists work out its inner structure.

In November, Russia will launch Fobos-Grunt, a mission to the larger of the two Martian moons, Phobos. All going well, it’ll touch down, grab some samples, and blast off back to Earth with them. The Chinese are piggybacking a small satellite too, which will orbit Mars and study its atmosphere, ionosphere and surface.

Finally, in December, there’ll be another launch of that Dragon capsule, plus the first launch of its competitor, called Cygnus. And to top it off, we’ll have another lunar eclipse.

Image credits: NASA / JPL-Caltech.

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Recycled spacecraft to revisit comet

An artist's impression of Stardust NExT approaching comet Tempel 1.

The Stardust NExT spacecraft will fly past comet Tempel 1 on February 15 (Sydney time) at a distance of only 200 kilometres.

NASA’S STARDUST NEXT SPACECRAFT is nearing a celestial date with comet Tempel 1 at approximately 3:37pm on February 15, Sydney time (11:37pm US EST on Feb 14). The mission will enable scientists for the first time to look for changes on a comet’s surface that occurred following an orbit around the Sun.

The Stardust-NExT, or New Exploration of Tempel, spacecraft will take high-resolution images during the encounter, and attempt to measure the composition, distribution, and flux of dust emitted into the coma…the cloud of material surrounding the comet’s core.

Data from the mission will provide important new information on how certain types of comets evolved and formed.

The mission will expand the investigation of the comet initiated by NASA’s Deep Impact mission. In July 2005, the Deep Impact spacecraft sent an impactor into the surface of Tempel 1 to study its composition. The Stardust spacecraft may capture an image of the crater formed by the impactor. This would be a bonus to the huge amount of data that mission scientists expect to obtain.

Here’s a short video of the result of Deep Impact’s impactor hitting Tempel 1:

“Every day we are getting closer and closer and more and more excited about answering some fundamental questions about comets,” said Joe Veverka, Stardust-NExT principal investigator at Cornell University.

“Going back for another look at Tempel 1 will provide new insights on how comets work and how they were put together four-and-a-half billion years ago.”

Close encounter of the comet kind

At approximately 336 million kilometres away from Earth, Stardust-NExT will be almost on the exact opposite side of the Solar System at the time of the encounter. (As of January 20, the spacecraft was approximately 24.6 million kilometres away from its encounter.) During the flyby, the spacecraft will take 72 images and store them in an onboard computer.

Initial raw images from the flyby will be sent to Earth for processing that will begin at approximately 7:00pm Sydney time on February 15. Images are expected to be made public 90 minutes later.

Since 2007, Stardust-NExT executed eight flight path correction manoeuvres, logged four circuits around the Sun and used one Earth gravity assist to meet up with Tempel 1.

Tempel 1 impact blast

The blast produced when an impactor released by the Deep Impact spacecraft, hit comet Tempel 1 in 2005. Scientist's hope Stardust NExT will give them a close-up look at the blast crater.

Another three manoeuvres are planned to refine the spacecraft’s path to the comet. Tempel 1’s orbit takes it as close in to the Sun as the orbit of Mars and almost as far away as the orbit of Jupiter. The spacecraft is expected to fly past the nearly 6-kilometre-wide comet at a distance of approximately 200 kilometres.

Running on empty

In 2004, Stardust became the first mission to collect particles directly from comet Wild 2, as well as interstellar dust. Samples were returned in 2006 for study via a capsule that detached from the spacecraft and parachuted to the ground southwest of Salt Lake City.

Mission controllers placed the still viable Stardust spacecraft on a trajectory that could potentially reuse the system if a target of opportunity presented itself.

In January 2007, NASA re-christened the mission Stardust-NExT and began a four-and-a-half year journey to comet Tempel 1.

“You could say our spacecraft is a seasoned veteran of cometary campaigns,” said Tim Larson, project manager for Stardust-NExT at NASA’s Jet Propulsion Laboratory.

“It’s been half-way to Jupiter, executed picture-perfect flybys of an asteroid and a comet, collected cometary material for return to Earth, then headed back out into the void again, where we asked it to go head-to-head with a second comet nucleus.”

The mission team expects this fly-by to write the final chapter of the spacecraft’s success-filled story. The spacecraft is nearly out of fuel as it approaches 12 years of space travel, logging almost 6 billion kilometres since launch in 1999.

This fly-by and planned post-encounter imaging are expected to consume the remaining fuel.

Adapted from information issued by NASA Jet Propulsion Laboratory.

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