World

500 million miles from Earth, probe awakes

An artist’s impression shows the Rosetta orbiter deploying a lander to comet 67P/Churyumov–Gerasimenko. A landing on the comet is scheduled for November.

European Space Agency

An artist’s impression shows the Rosetta orbiter deploying a lander to comet 67P/Churyumov–Gerasimenko. A landing on the comet is scheduled for November.

BERLIN — Waking up after almost three years of hibernation, a comet-chasing spacecraft sent its first signal back to Earth on Monday, prompting cheers from scientists who hope to use it to place the first space lander onto a comet.

The European Space Agency received the all-clear message from its Rosetta spacecraft at 7:18 p.m. — a message that had to travel some 500 million miles.

Advertisement

In keeping with the agency’s effort to turn the tense wait for a signal into a social media event, the probe triggered a series of ‘‘Hello World!’’ tweets in different languages.

Dormant systems on the unmanned spacecraft were switched back on in preparation for the final stage of its decade-long mission to rendezvous with the comet named 67P/Churyumov-Gerasimenko. Systems had been powered down in 2011 to conserve energy, leaving scientists in the dark about the probe’s fate until now.

Get Todays Headlines in your inbox:
Thank you for signing up! Sign up for more newsletters here

Because of the time it took Rosetta to wake up, and the long distance between the spacecraft and Earth, the earliest possible hour for a signal to arrive was 6:30 p.m.

‘‘I think it’s been the longest hour of my life,’’ said Andrea Accomazzo, the spacecraft’s operations manager at ESA’s mission control room in Darmstadt, Germany. ‘‘Now we have it back.’’

Scientists will now take control of Rosetta again, a procedure slowed by the 45 minutes it takes a signal to travel to or from the spacecraft, he said.

Advertisement

The wake-up call is one of the final milestones for Rosetta before it makes its rendezvous with comet 67P in the summer.

The probe will then fly a series of complicated maneuvers to observe the comet — a lump of rock and ice about 2.5 miles in diameter — before dropping a lander called Philae onto its icy surface in November.

The lander will dig up samples and analyze them with its instruments.

Although the spacecraft was launched almost a decade ago, the instruments aboard Rosetta and the Philae lander are still considered cutting edge, said Joel Parker of the Southwest Research Institute in Boulder, Colo. The institute developed a specialized camera called ALICE that can detect different chemicals in the comet.

Rosetta is named after a block of stone that allowed archeologists to decipher ancient Egyptian hieroglyphs. Scientists hope the space mission will help them understand the composition of comets and thereby discover more about the origins and evolution of our solar system.

Comets are regarded as flying time capsules because they are essentially unchanged for the last 4.6 billion years. Scientists have speculated that comets may be responsible for the water found on some planets. And like asteroids, comets also pose a theoretical threat to life on Earth.

Loading comments...
You're reading  1 of 5 free articles.
Get UNLIMITED access for only 99¢ per week Subscribe Now >
You're reading1 of 5 free articles.Keep scrolling to see more articles recomended for you Subscribe now
We hope you've enjoyed your 5 free articles.
Continue reading by subscribing to Globe.com for just 99¢.
 Already a member? Log in Home
Subscriber Log In

We hope you've enjoyed your 5 free articles'

Stay informed with unlimited access to Boston’s trusted news source.

  • High-quality journalism from the region’s largest newsroom
  • Convenient access across all of your devices
  • Today’s Headlines daily newsletter
  • Subscriber-only access to exclusive offers, events, contests, eBooks, and more
  • Less than 25¢ a week
Marketing image of BostonGlobe.com
Marketing image of BostonGlobe.com
Already a subscriber?
Your city. Your stories. Your Globe.
Yours FREE for two weeks.
Enjoy free unlimited access to Globe.com for the next two weeks.
Limited time only - No credit card required!
BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.
Thanks & Welcome to Globe.com
You now have unlimited access for the next two weeks.
BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.