News / Science & Technology

US Spacecraft to Rendezvous with Asteroid

Artist's rendition of Dawn spacecraft leaving Earth
Artist's rendition of Dawn spacecraft leaving Earth

An unmanned U.S. spacecraft named Dawn is heading toward a huge space rock, with a rendezvous expected on July 16.  NASA scientists say they hope the unprecedented encounter in the asteroid belt will shed light on the history of the solar system.

Vesta is not just any asteroid.  At 530 kilometers in diameter, it is the second most massive object in the asteroid belt - a vast region between Mars and Jupiter that is filled with rocky debris.  Scientists call Vesta a "protoplanet" because it almost formed into a planet like Mars or Earth.

And now Vesta is getting a visitor - the Dawn spacecraft.  

Robert Mase is the Dawn project manager at NASA's Jet Propulsion Laboratory in California.  He spoke to reporters at a mission preview briefing late last month.

"After traveling for nearly four years, 1.7 billion miles [2.7 billion kilometers] and two laps around the Sun, Dawn is finally on our final approach to Vesta," Mase said.

And this week, as the rendezvous date approaches, Mase says Dawn is right on target.  

NASA's Dawn spacecraft is expected to fall into orbit around Vesta on July 16.  After Vesta captures Dawn in its orbit, engineers estimate they will be about 16,000 kilometers apart.

The spacecraft has sent back pictures of Vesta, and the images are far sharper than the ones taken by the Earth-orbiting Hubble Space Telescope.  Researchers already are expressing surprise at the asteroid's extremely varied surface features.  But the real science gathering is not even expected to begin until next month.

But how does a spacecraft get from the Earth to the asteroid belt?  Dawn relies partially on solar energy.  The spacecraft has two solar panels, totaling about 16 meters in length.  Dawn's wingspan is about 20 meters, which NASA's Robert Mase says makes Dawn the largest interplanetary spacecraft the US space agency has ever launched.  Plus, Dawn has three ion engines.  That type of propulsion might be familiar to science fiction fans, as an alien spacecraft used it in the 1960s American television series "Star Trek."   

Ion engines are efficient because they are powered by electrical fields, not chemical reactions.

Robert Mase says ion engines initially produce very low thrust. "About as much as a single piece of paper would push down on your hand.  So this means we go from zero to 60 [miles per hour, or about 95 kilometers per hour] in about four days.  But the ion engine can continue to thrust and accelerate, day after day, month after month, eventually achieving tremendous velocities over time," Mase said.  

Dawn will spend a year orbiting Vesta - the first prolonged visit to a main belt asteroid.  It will map the mineral composition and features of Vesta's surface, collect information about Vesta's gravity field and peer into a massive crater that might expose the asteroid's core.  

Then Dawn will fire its engines and fly toward the dwarf planet Ceres - the largest object in the asteroid belt.  It is expected to orbit Ceres in early 2015, and spend several months gathering data.

Mase says the Dawn mission is unusual because the spacecraft will rendezvous with not one, but two bodies in the solar system.

Researchers say Vesta is no stranger to Earth.  Chunks of the protoplanet have been knocked off during collisions with other space rocks.  Scientists theorize that perhaps five percent of the meteorites on Earth originated on Vesta.

You May Like

India PM Modi's party distances itself from religious conversions

BJP under fire for being slow to rein in hardline affiliate groups allegedly trying to promote a Hindu-dominant agenda by luring Muslims and Christians to convert to Hinduism More

Anti-Whaling Group Found in Contempt of Court

Radical environmentalists who threw acid and smoke bombs at Japanese whalers in the waters off Antarctica continue their campaign to disrupt Japan's annual whale hunt More

UN's Ban Urges End to Discrimination Against Ebola Workers

Ban was speaking in Guinea on the second day of a whistle-stop tour aimed at thanking healthcare workers of the countries at the heart of the epidemic More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Sudan School Becomes Target of Aerial Attacksi
X
December 19, 2014 12:45 AM
The school dropout rate is at an all-time high in Sudan's South Kordofan state because many schools have been destroyed during the three-year civil war between the government and SPLA-N rebel forces. Adam Bailes visited Sudan's Nuba Mountains' region and reports many children are simply too scared to go to school
Video

Video Sudan School Becomes Target of Aerial Attacks

The school dropout rate is at an all-time high in Sudan's South Kordofan state because many schools have been destroyed during the three-year civil war between the government and SPLA-N rebel forces. Adam Bailes visited Sudan's Nuba Mountains' region and reports many children are simply too scared to go to school
Video

Video VOA Reporter Tours Devastated Peshawar School

Islamist militants wearing military uniforms and strapped with explosives attacked a military run school Tuesday in the northwestern Pakistani city of Peshawar. At least 141 people were killed in the horrific attack, most of them young students. VOA reporter Ayaz Gul visited the devastated school and attended the funeral of the principal who courageously tried to save her students from the deadly attack.
Video

Video Nigerians Fleeing Boko Haram Languish in Camp Near Capital

In its five-year effort to impose Islamic law in northeastern Nigeria, the Boko Haram extremist group has killed thousands of people and forced hundreds of thousands to flee. Some of those who ran for their lives now live in squalor on the edges of the capital, Abuja. Chris Stein reports for VOA.
Video

Video Putin Says Russian Economy Will Emerge Stronger

Russian President Vladimir Putin has said his country's sinking economy will not only recover but also become stronger, despite falling oil prices and Western sanctions over Ukraine. VOA's Daniel Schearf reports.
Video

Video Detained Turkish Journalists Follow Teachings of US-Based Preacher

The Turkish government’s jailing of critical journalists has sparked international condemnation and is being seen as an effort to undermine the followers of an ailing Turkish preacher based in the United States. VOA religion reporter Jerome Socolovsky has more.
Video

Video ‘Anti-Islamization’ Marches Increase Tensions In Germany

Anti-immigrant rallies in Germany have been building in recent weeks, peaking Monday night in the city of Dresden where tens of thousands of people turned out to demonstrate against what they call the ‘Islamization’ of the West. Germany has offered asylum to more Syrian refugees than any other country, and this appears to have set off the protests. Henry Ridgwell reports from London.
Video

Video Aceh Rebuilt Decade After Tsunami, But Scars Remain

On December 26, 2004 there was an earthquake in the Indian Ocean so powerful it caused the Earth’s axis to wobble a few centimeters. Onshore on the island of Sumatra, the resulting tsunami was devastating. A decade later, VOA Correspondent Steve Herman reports from Banda Aceh, Indonesia, where although there is little remaining evidence of the physical devastation, the psychological scars among survivors remain.
Video

Video Refugees Living in Kenya Long for Peace in the Home Countries

Kenya is host to numerous refugees seeking safe haven from conflict. Immigrants from Somalia face challenges in their new lives in Kenya. Ahead of International Migrants Day (December 18) Lenny Ruvaga has more for VOA News from the Kenyan capital.

All About America

AppleAndroid