Featured Research

from universities, journals, and other organizations

NASA-Built Atomic Clock Does The Time Warp, Again

Date:
September 24, 2002
Source:
NASA/Jet Propulsion Laboratory
Summary:
A team of physicists and engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., has developed an improved way to release the time genie from its bottle, so to speak. Building upon more than a decade of work on a frequency standard called the linear ion trap, the JPL Frequency Standards Laboratory team has developed and installed a new trapped ion atomic clock for the U.S. Naval Observatory in Washington that essentially eliminates these walls. These recent JPL innovations are expected to provide 20 times improved stability over previous trapped ion clocks. The result is a clock that's effective stability is equivalent to about one minute in 10 billion years-the approximate age of the universe.

A '70s song by the late singer Jim Croce begins, "If I could save time in a bottle..." And when it comes to atomic clocks-those ultra-precise standard-keepers to which other precision timekeeping devices are set-some do just that. Atoms of an element are often held in a glass vacuum chamber whose walls are coated to prevent the atoms' collision with the walls from altering their internal compositions. Inevitably, however, such collisions still distort the atoms and make them 'tick' differently, causing the clocks to run fast or slow.

Now a team of physicists and engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., has developed an improved way to release the time genie from its bottle, so to speak. Building upon more than a decade of work on a frequency standard called the linear ion trap, the JPL Frequency Standards Laboratory team has developed and installed a new trapped ion atomic clock for the U.S. Naval Observatory in Washington that essentially eliminates these walls. These recent JPL innovations are expected to provide 20 times improved stability over previous trapped ion clocks. The result is a clock that's effective stability is equivalent to about one minute in 10 billion years-the approximate age of the universe.

The instrument, based on mercury ions, will be measured with a large ensemble of atomic clocks operated to form a very stable, continuous timescale at the U.S. Naval Observatory, which serves as the center of all U.S. Department of Defense timekeeping and supports the needs of the Global Positioning System, or GPS. During this evaluation, the ion clock will also be used as a frequency reference for transcontinental time and frequency transfer comparisons to be performed between the Observatory and the only other ion clock of its kind, located at JPL.

"These trapped ion atomic clocks are designed for long-term stability, continuous operation and high reliability," said Dr. Robert Tjoelker, supervisor of JPL's Frequency and Timing Advanced Instrumentation Development Group. "Long-term timekeeping is an ideal application for the technology."

In the linear ion trap frequency standard, mercury ions--atoms with an electron removed-- collide not with a wall but with an applied electric force field. The field completely surrounds the ions, forming a container called an ion trap. "Atomic ions colliding with this sort of 'wall' are disturbed about 10,000 times less than in glass cell-based atomic clocks," said Dr. John Prestage of the JPL Quantum Sciences and Technology Group. Because the mercury ions have a positive charge, they can be held with oscillating electric fields in a container produced with metallic electrodes inside an ultra-high vacuum system, and made into a clock.

Like all clocks, atomic clocks measure frequency of a recurring event to keep time. A wonder of quantum mechanics that govern the world of atoms is that every isolated atom in the universe is exactly the same as every other atom of the same element and containing the same number of neutrons. Atomic clocks have unique measurement capability because every atom or ion in the clock is quantum-mechanically identical to every other one. Therefore, by measuring the transition of atoms as they move back and forth between two energy levels, atomic clocks provide an absolute reference for frequency and time. Their success is such that time and frequency are today measured with far higher accuracy than any other physical quantity.

One use of the time scale maintained at the U.S. Naval Observatory is to monitor onboard GPS space clocks and reset them periodically to keep the GPS radio navigation system working so well. These onboard clocks aren't as accurate as the ground clock ensemble maintained at the Observatory.

NASA uses atomic clocks to provide reliable and consistent navigation for interplanetary space travel, where fractional disparities in clock tick rates can dramatically affect the navigation of spacecraft. Trapped ion clock technology currently operates in NASA's Deep Space Network and is also being developed for small, low-mass and low-power space flight applications.

The U.S. Naval Observatory performs an essential scientific role for the United States, Navy and Department of Defense. Its mission includes determining positions and motions of the Earth, Sun, Moon, planets, stars and other celestial objects, providing astronomical data; determining precise time; measuring Earth's rotation; and maintaining the Master Clock for the U.S. Department of Defense. Observatory astronomers formulate the theories and conduct the relevant research necessary to improve these mission goals. This astronomical and timing data, essential for accurate navigation and support of communications on Earth and in space, is vital to the Navy and Department of Defense and is used extensively by other government agencies and the public at large.

JPL is NASA's lead center for frequency and time and is responsible for technology development, generation, and distribution of ultra-stable reference frequencies and synchronized timing signals for the Deep Space Network. NASA's Office of Space Flight, Washington, D.C., supports JPL's linear ion trap frequency standard research.

JPL is a division of the California Institute of Technology in Pasadena.


Story Source:

The above story is based on materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Jet Propulsion Laboratory. "NASA-Built Atomic Clock Does The Time Warp, Again." ScienceDaily. ScienceDaily, 24 September 2002. <www.sciencedaily.com/releases/2002/09/020924071844.htm>.
NASA/Jet Propulsion Laboratory. (2002, September 24). NASA-Built Atomic Clock Does The Time Warp, Again. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2002/09/020924071844.htm
NASA/Jet Propulsion Laboratory. "NASA-Built Atomic Clock Does The Time Warp, Again." ScienceDaily. www.sciencedaily.com/releases/2002/09/020924071844.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Graphene Paint Offers Rust-Free Future

Graphene Paint Offers Rust-Free Future

Reuters - Innovations Video Online (Oct. 21, 2014) British scientists have developed a prototype graphene paint that can make coatings which are resistant to liquids, gases, and chemicals. The team says the paint could have a variety of uses, from stopping ships rusting to keeping food fresher for longer. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Gulfstream G500, G600 Unveiling

Gulfstream G500, G600 Unveiling

Flying (Oct. 20, 2014) Watch Gulfstream's public launch of the G500 and G600 at their headquarters in Savannah, Ga., along with a surprise unveiling of the G500, which taxied up under its own power. Video provided by Flying
Powered by NewsLook.com
Japanese Scientists Unveil Floating 3D Projection

Japanese Scientists Unveil Floating 3D Projection

Reuters - Innovations Video Online (Oct. 20, 2014) Scientists in Tokyo have demonstrated what they say is the world's first 3D projection that floats in mid air. A laser that fires a pulse up to a thousand times a second superheats molecules in the air, creating a spark which can be guided to certain points in the air to shape what the human eye perceives as an image. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins