Skip to main content

Why Rosetta spacecraft chased after a comet

By Jim Bell
updated 11:43 AM EDT, Fri August 8, 2014
After a 10-year chase taking it billions of miles across the solar system, the European Space Agency's Rosetta spacecraft became the first probe to orbit a comet after arriving at its destination on August 6. The spacecraft recently took this image of comet 67P/Churyumov-Gerasimenko. In November, Rosetta will deploy a robotic lander to the comet's surface -- something that also has never been done before. The box on the right shows where the lander will touch down. After a 10-year chase taking it billions of miles across the solar system, the European Space Agency's Rosetta spacecraft became the first probe to orbit a comet after arriving at its destination on August 6. The spacecraft recently took this image of comet 67P/Churyumov-Gerasimenko. In November, Rosetta will deploy a robotic lander to the comet's surface -- something that also has never been done before. The box on the right shows where the lander will touch down.
HIDE CAPTION
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
Rosetta: The comet chaser
<<
<
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
>
>>
STORY HIGHLIGHTS
  • Rosetta mission becomes the first spacecraft to go into orbit around a comet
  • Jim Bell: Will it find organic molecules that could help seed a planet like ours for life?
  • He says mission will look for connection between small, icy bodies and large planets
  • Bell: The comet's details are waiting to be deciphered, and that's exciting for science

Editor's note: Jim Bell is an astronomer and planetary scientist in the School of Earth and Space Exploration at Arizona State University. He is president of The Planetary Society and author of "Postcards from Mars," "The Space Book" and most recently, "The Interstellar Age," due out in early 2015. The opinions expressed in this commentary are solely those of the author.

(CNN) -- More than 200 years ago, part of a stone tablet was discovered in Egypt that provided the first reliable way to translate ancient hieroglyphics into a modern language. The Rosetta Stone, as the tablet is called, proved to be the key to unlocking details of the rise and fall of civilizations that flourished on our planet many thousands of years ago.

More recently, a space mission bearing the name Rosetta has begun its quest of unlocking details of the rise and fall of entire planets, including the only one we know that is a safe haven for life.

The European Space Agency's Rosetta mission is a robotic spacecraft designed to get up close and personal with the nucleus of a comet. The comet is called 67P/C-G (short for Churyumov--Gerasimenko, the astrophysicists who discovered it in 1969), and it orbits the sun on a 6½ year elliptical path that takes it from just beyond the orbit of Jupiter to just outside the orbit of Earth.

Rosetta: CNN special coverage

But that orbit is relatively new. 67P/C-G is thought to have originated from much farther away, but one or more close passes by Jupiter altered its orbit, pushing it closer in to the Sun. Thus, 67P/C-G may very well be a piece of primordial, icy debris left over from the original formation of our solar system more than 4½ billion years ago.

It's the Rosetta mission team's job to find out if that is indeed the case, and if there is a specific connection between small, icy bodies like this one and the larger terrestrial planets that they have helped build over the course of solar system history.

Launched a decade ago, the spacecraft -- like the comet it was designed to encounter -- was sent on a long, slow, looping trajectory, passing back by Earth and even Mars for gravity assists, and flying past main belt asteroids Steins and Lutetia along the way.

Rosetta spacecraft first to orbit a comet
Rosetta closing in on comet
Could Rosetta unlock Earth's secrets?

In fact, the cruise to 67P/C-G was so long, and so slow, that the spacecraft was actually put into a state of robotic hibernation for nearly three years to help save money. In a great demonstration of both outstanding engineering and phenomenal patience, scientists and engineers returning to the project this past January were ecstatic when the spacecraft woke successfully from its long interplanetary slumber.

Rosetta team members, including a number of NASA-funded U.S. engineers and planetary scientists, were ecstatic again this week as their plucky little robot successfully nuzzled up to the 2½ mile wide nucleus of 67P/C-G to become the first spacecraft to go into orbit around a comet.

"Nuzzled" is an appropriate word, because with a gravity field more than 10,000 times weaker than Earth's, the pull of this tiny comet is only barely felt by the spacecraft. And not only is it tiny, but it seems to also be just plain weird!

Early Rosetta images show the comet looks like a strange, lumpy, double-lobed peanut covered by cliffs, circular ridges and smooth plains. The "neck" between the two main lobes looks almost fragile from certain angles, suggesting the comet might be about to break into two large chunks. That might perhaps not be a surprising fate, as this small icy world is steadily evaporating, jetting huge amounts of dust, water vapor and other gases into space as it basks in the warmth of the sun.

But the best is still yet to come for Rosetta. The mission's dozen science instruments have only just started to characterize the comet in detail, providing chemical, mineral and geologic clues about its origin and evolution.

In November, the team will attempt to set the oven-sized Philae lander (named after another important Egyptian hieroglyph artifact) down onto the comet to make even more precise direct measurements of the surface. It will be a daring, slow-motion adventure, shared with the world, as Philae descends and then struggles to hang on to the surface under the ultra-weak gravity.

Is this small icy body the kind of world responsible for delivering oceans' worth of water to our planet and others? Are the kinds of organic molecules that Rosetta and Philae might find there the kinds of materials that could help seed a planet like ours for life? What kinds of spectacular sights await as the spacecraft follows the comet even closer to the sun, where the surface is predicted to become even more active?

67P/C-G's planetary hieroglyphics are waiting to be deciphered, and I can't wait to find out what they say!

Read CNNOpinion's new Flipboard magazine

Follow us on Twitter @CNNOpinion.

Join us on Facebook.com/CNNOpinion.

ADVERTISEMENT
Part of complete coverage on
updated 12:53 PM EDT, Tue September 30, 2014
Jeff Yang calls Ello a wakeup call to Facebook and Twitter, and a sign of hope for fast-rising upstarts Pinterest and Snapchat.
updated 10:23 AM EDT, Wed October 1, 2014
Paul Waldman says the Secret Service should examine its procedures to make sure there are no threats to the White House--but without losing the openness so valuable to democracy
updated 10:25 AM EDT, Wed October 1, 2014
Jesse Williams says the videotape and 911 call that resulted in police gunning down John Crawford at a Walmart reveals the fatal injustice of racial assumptions
updated 7:03 PM EDT, Tue September 30, 2014
Mel Robbins says officials should drop the P.C. pose: The beheading in Oklahoma was not workplace violence. Plenty of evidence shows Alton Nolen was an admirer of ISIS.
updated 3:11 PM EDT, Tue September 30, 2014
The Occupy Central movement has already achieved much by bringing greater attention to Hong Kong's struggle for democracy, William Piekos says..
updated 3:11 PM EDT, Tue September 30, 2014
The Occupy Central movement has already achieved much by bringing greater attention to Hong Kong's struggle for democracy, writes William Piekos.
updated 10:13 AM EDT, Tue September 30, 2014
As Prime Minister Narendra Modi visits America, Madeleine Albright says a world roiled by conflict needs these two great democracies to commit to moving their partnership forward
updated 10:04 AM EDT, Tue September 30, 2014
John Sutter: Lake Providence, Louisiana, is the parish seat of the "most unequal place in America." And until somewhat recently, the poor side of town was invisible on Google Street View.
updated 9:11 AM EDT, Mon September 29, 2014
Julian Zelizer says in the run up to the 2016 election the party faces divisions on its approach to the U.S.'s place in the world
updated 10:19 AM EDT, Mon September 29, 2014
Ruben Navarrette says Common Core supporters can't devise a new set of standards and then fail to effectively sell it.
updated 9:29 AM EDT, Tue September 30, 2014
Earlier this month, Kenyans commemorated the heinous attack on the Westgate Mall in Nairobi.
updated 2:59 PM EDT, Tue September 30, 2014
David Wheeler says Colorado students are right to protest curriculum changes that downplays civil disobedience.
updated 9:58 PM EDT, Fri September 26, 2014
Sally Kohn says when people click on hacked celebrity photos or ISIS videos, they are encouraging the bad guys.
updated 7:55 AM EDT, Fri September 26, 2014
Loren Bunche says she walked by a homeless man every day and felt bad about it -- until one day she paused to get to know him
updated 9:32 AM EDT, Tue September 30, 2014
ISIS grabs headlines on social media, but hateful speech is no match for moderate voices, says Nadia Oweidat.
updated 8:33 AM EDT, Mon September 29, 2014
A new report counts jihadists fighting globally. The verdict? The threat isn't that big, says Peter Bergen.
updated 5:37 PM EDT, Tue September 23, 2014
Ebola could become the biggest humanitarian disaster in a generation, writes former British Prime Minister Tony Blair
updated 12:58 PM EDT, Fri September 26, 2014
ISIS has shocked the world. But will releasing videos of executions backfire? Four experts give their take.
updated 10:39 AM EDT, Fri September 26, 2014
Eric Holder kicked off his stormy tenure as attorney general with a challenge to the public that set tone for six turbulent years as top law-enforcement officer.
updated 9:09 AM EDT, Fri September 26, 2014
LZ Granderson says Obama was elected as a war-ending change agent, not a leader who would leave behind for his successor new engagement in Iraq and Syria. Is he as disappointed as the rest of us?
updated 5:10 AM EDT, Wed September 24, 2014
Gayle Lemmon says the question now is how to translate all the high-profile feminizing into real gains for women
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT