News / Science & Technology

    Electric Engines Keep Many Satellites in Orbit

    This NASA image shows an artist rendering of the Juno spacecraft circling Jupiter.
    This NASA image shows an artist rendering of the Juno spacecraft circling Jupiter.
    George Putic

    Among the challenges of deep-space travel is the amount of fuel needed for long flights. One of the solutions could be the electrical engine, powered by electricity from solar panels. Such engines already are in use aboard many satellites.

    Physicists consider gravity a weak force. After all, we overcome its pull each morning when we get out of bed!

    However, launching a satellite requires more effort: a large rocket and a lot of chemical fuel, which is quickly burned as it powers upward. Once the payload reaches about 160 kilometers above the earth, the effect of gravity has weakened enough for it to stay in orbit.

    A one-way mission into deep space would require even more fuel, according to NASA senior technologist for space propulsion, Michael Patterson.

    “For any mission application, particularly in deep space, the energy required to do the mission is huge, so the propellant fraction is typically quite large," he said.

    Patterson said in the 1950s, the space agency started experimenting with so-called electric propulsion, or EP - - a jet of electrically charged particles that does not require too much power. Once in space, an EP-craft would keep gradually accelerating toward its destination, moving faster and faster the longer it travels. After four years, for example, it could be travelling at 10 kilometers a second.

    Ion jets

    That makes it ideal for long-range missions. But while NASA was testing EP for deep-space voyaging, engineers found another application for ion jets closer to our home planet.

    The gravity of the sun, moon and earth constantly pull on geosynchronous commercial satellites, which stay in the same position relative to earth. Electric propulsion proved to be very useful for making sure that they stay in their required position.

    Patterson says out of approximately 250 geosynchronous satellites in orbit today, about 43 percent have some form of EP on board.

    Applications for deep space missions had to wait for another decade.

    “It wasn’t until the 1990s where electric propulsion actually started being used by NASA for a NASA mission and that was with the advent if the ion thruster technology that was flown on the Deep Space One mission.”

    Efficient propulsion

    Scientists continue to experiment with other forms of propulsion that require even less energy. While NASA is developing the next generation ion propulsion system called NEXT, others are experimenting with more radical concepts, such as Q-Thruster, that uses radio-frequency microwaves instead of charged particle jets.

    Critics call it “the impossible engine,” saying that the concept violates the basic principles of physics, while proponents say they have proof that it has actually generated thrust.

    Patterson points out that EP is not appropriate for crewed missions in earth’s orbital environment or for travel to the moon, because it would take too long.

    “Crossover point is in the kind of, Mars kind of destination, or beyond, meaning, if you have enough power on board it starts to possibly may make sense to use electrical propulsion for a crewed mission,” said Patterson.

    He said for now, however, it would be reasonable to use EP for big unmanned vehicles taking cargo to Mars orbit, to support human infrastructure on the ground.

     

     

     

     

    You May Like

    US Internet Giants, EU Reach Deal to Combat Online Hate Speech

    Facebook, Twitter, Google and Microsoft commit to ‘quickly and efficiently’ act to clamp down on use of social media to incite violence, terror

    Tunisia’s Ennahda Party Begins a New Political Chapter

    Party now moves to separate its political and religious activities; change described by party members as pragmatic response to political and economic challenges facing Tunisia today

    Virtual Reality Fine-tuned at Asia Tech Show

    Microchip designers hope to improve resolution for users of systems that can turn your bedroom into the ocean floor

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Tech Startups Showcase Wares at Amsterdam Conferencei
    X
    Serginho Roosblad
    May 30, 2016 5:11 PM
    More than 20,000 tech enthusiasts, entrepreneurs and lovers of digital technology came together in Amsterdam recently at the Next Web Conference to discuss the latest developments in digital technology, look to the future and, of course, to connect. In recent years, there has been an explosion of so-called startup businesses that have created devices and applications that have changed the way we live; but, as Serginho Roosblad reports for VOA, there are pitfalls for such startups as well.
    Video

    Video Tech Startups Showcase Wares at Amsterdam Conference

    More than 20,000 tech enthusiasts, entrepreneurs and lovers of digital technology came together in Amsterdam recently at the Next Web Conference to discuss the latest developments in digital technology, look to the future and, of course, to connect. In recent years, there has been an explosion of so-called startup businesses that have created devices and applications that have changed the way we live; but, as Serginho Roosblad reports for VOA, there are pitfalls for such startups as well.
    Video

    Video US Military's Fallen Honored With Flags

    Memorial Day is a long weekend for most Americans. For some, it is the unofficial start of summer -- local swimming pools open and outdoor grilling season begins. But Memorial Day remains true to its origins -- a day to remember the U.S. military's fallen.
    Video

    Video Rolling Thunder Rolls Into Washington

    The Rolling Thunder caravan of motorcycles rolled into Washington Sunday, to support the U.S. military on the country's Memorial Day weekend
    Video

    Video A New Reading Program Pairs Kids with Dogs

    Dogs, it is said, are man's best friend. What some researchers have discovered is that they can also be a friend to a struggling reader. A group called Intermountain Therapy Animals trains dogs to help all kinds of kids with reading problems — from those with special needs to those for whom English is a second language. Faiza Elmasry has more on the New York chapter of R.E.A.D., or Reading Education Assistance Dogs, in this piece narrated by Faith Lapidus.
    Video

    Video Fan Base Grows for Fictional Wyoming Sheriff Longmire

    Around the world, the most enduring symbol of the U.S. is that of the cowboy. A very small percentage of Americans live in Western rural areas, and fewer still are cowboys. But the fascination with the American West is kept alive by such cultural offerings as “Longmire,” a series of books and TV episodes about a fictional Wyoming sheriff. VOA’s Greg Flakus recently spoke with Longmire’s creator, Craig Johnson, and filed this report from Houston.
    Video

    Video Chinese-Americans Heart Trump, Bucking National Trend

    A new study conducted by three Asian-American organizations shows there are three times as many Democrats as there are Republicans among Asian-American voters, and they favor Hillary Clinton over Donald Trump. But one group, called Chinese-Americans For Trump, is going against the tide and strongly supports the business tycoon. VOA’s Elizabeth Lee caught up with them at a Trump rally and reports from Anaheim, California.
    Video

    Video Reactions to Trump's Success Polarized Abroad

    What seemed impossible less than a year ago is now almost a certainty. New York real estate mogul Donald Trump has won the number of delegates needed to secure the Republican presidential nomination. The prospect has sparked as much controversy abroad as it has in the United States. Zlatica Hoke has more.
    Video

    Video Drawings by Children in Hiroshima Show Hope and Peace

    On Friday, President Barack Obama will visit Hiroshima, Japan, the first American president to do so while in office. In August 1945, the United States dropped an atomic bomb on the city to force Japan's surrender in World War II. Although their city lay in ruins, some Hiroshima schoolchildren drew pictures of hope and peace. The former students and their drawings are now part of a documentary called “Pictures from a Hiroshima Schoolyard.” VOA's Deborah Block has the story.
    Video

    Video Vietnamese Rapper Performs for Obama

    A prominent young Vietnamese artist told President Obama said she faced roadblocks as a woman rapper, and asked the president about government support for the arts. He asked her to rap, and he even offered to provide a base beat for her. Watch what happened.
    Video

    Video Roots Run Deep for Tunisia's Dwindling Jewish Community

    This week, hundreds of Jewish pilgrims are defying terrorist threats to celebrate an ancient religious festival on the Tunisian island of Djerba. The festivities cast a spotlight on North Africa's once-vibrant Jewish population that has all but died out in recent decades. Despite rising threats of militant Islam and the country's battered economy, one of the Arab world's last Jewish communities is staying put and nurturing a new generation. VOA’s Lisa Bryant reports.

    Special Report

    Adrift The Invisible African Diaspora