JPL
Careers
Education
Science & Technology
JPL Logo
JPL Logo
Technology
.

Deep Space Atomic Clock Moves Toward Increased Spacecraft Autonomy

June 30, 2021

NASA’s Deep Space Atomic Clock has been operating aboard the General Atomics Orbital Test Bed satellite since June 2019. This illustration shows the spacecraft in Earth orbit.

Credit: General Atomics Electromagnetic Systems

NASA’s Deep Space Atomic Clock could revolutionize deep space navigation. One key requirement for the technology demonstration was a compact design. The complete hardware package is shown here and is only about 10 inches (25 centimeters) on each side.

Credit: NASA/JPL-Caltech

Designed to improve navigation for robotic explorers and the operation of GPS satellites, the technology demonstration reports a significant milestone.

Spacecraft that venture beyond our Moon rely on communication with ground stations on Earth to figure out where they are and where they’re going. NASA’s Deep Space Atomic Clock is working toward giving those far-flung explorers more autonomy when navigating. In a new paper published today in the journal Nature, the mission reports progress in their work to improve the ability of space-based atomic clocks to measure time consistently over long periods.

Known as stability, this feature also impacts the operation of GPS satellites that help people navigate on Earth, so this work also has the potential to increase the autonomy of next-generation GPS spacecraft.

What Is an Atomic Clock?
Getting Humans to Mars on Time

To calculate the trajectory of a distant spacecraft, engineers send signals from the spacecraft to Earth and back. They use refrigerator-size atomic clocks on the ground to log the timing of those signals, which is essential for precisely measuring the spacecraft’s position. But for robots on Mars or more distant destinations, waiting for the signals to make the trip can quickly add up to tens of minutes or even hours.

If those spacecraft carried atomic clocks, they could calculate their own position and direction, but the clocks would have to be highly stable. GPS satellites carry atomic clocks to help us get to our destinations on Earth, but those clocks require updates several times a day to maintain the necessary level of stability. Deep space missions would require more stable space-based clocks.

Managed by NASA’s Jet Propulsion Laboratory in Southern California, the Deep Space Atomic Clock has been operating aboard General Atomic’s Orbital Test Bed spacecraft since June 2019. The new study reports that the mission team has set a new record for long-term atomic clock stability in space, reaching more than 10 times the stability of current space-based atomic clocks, including those on GPS satellites.

NASA has perfected new navigation technology that would make self-driving spacecraft and GPS beyond the Moon a reality. The Deep Space Atomic Clock is the first atomic clock small and stable enough to fly on a spacecraft beyond Earth's orbit. As NASA works to put humans on Mars and the Moon, the clock’s precise timekeeping will be key to these missions’ success.

Credit: NASA/JPL-Caltech

When Every Nanosecond Counts

All atomic clocks have some degree of instability that leads to an offset in the clock’s time versus the actual time. If not corrected, the offset, while miniscule, increases rapidly, and with spacecraft navigation, even a tiny offset could have drastic effects.

One of the key goals of the Deep Space Atomic Clock mission was to measure the clock’s stability over longer and longer periods, to see how it changes with time. In the new paper, the team reports a level of stability that leads to a time deviation of less than four nanoseconds after more than 20 days of operation.

“As a general rule, an uncertainty of one nanosecond in time corresponds to a distance uncertainty of about one foot,” said Eric Burt, an atomic clock physicist for the mission at JPL and co-author of the new paper. “Some GPS clocks must be updated several times a day to maintain this level of stability, and that means GPS is highly dependent on communication with the ground. The Deep Space Atomic Clock pushes this out to a week or more, thus potentially giving an application like GPS much more autonomy.”

Get the Latest JPL News

SUBSCRIBE TO THE NEWSLETTER

The stability and subsequent time delay reported in the new paper is about five times better than what the team reported in the spring of 2020. This does not represent an improvement in the clock itself, but in the team’s measurement of the clock’s stability. Longer operating periods and almost a full year of additional data made it possible to improve the precision of their measurement.

The Deep Space Atomic Clock mission will conclude in August, but NASA announced that work on this technology continues: the Deep Space Atomic Clock-2, an improved version of the cutting-edge timekeeper, will fly on the VERITAS (short for Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) mission to Venus. Like its predecessor, the new space clock is a technology demonstration, meaning its goal is to advance in-space capabilities by developing instruments, hardware, software, or the like that doesn't currently exist. Built by JPL and funded by NASA’s Space Technology Mission Directorate (STMD), the ultra-precise clock signal generated with this technology could help enable autonomous spacecraft navigation and enhance radio science observations on future missions.

“NASA’s selection of Deep Space Atomic Clock-2 on VERITAS speaks to this technology’s promise,” said Todd Ely, Deep Space Atomic Clock principal investigator and project manager at JPL. “On VERITAS, we aim to put this next generation space clock through its paces and demonstrate its potential for deep space navigation and science.”

More About the Mission

The Deep Space Atomic Clock is hosted on a spacecraft provided by General Atomics Electromagnetic Systems of Englewood, Colorado. It is sponsored by STMD’s Technology Demonstration Missions program located at NASA’s Marshall Space Flight Center in Huntsville, Alabama, and NASA’s Space Communications and Navigation (SCaN) program within NASA’s Human Exploration and Operations Mission Directorate. JPL manages the project.

News Media Contact

Calla Cofield

Jet Propulsion Laboratory, Pasadena, Calif.

626-808-2469

calla.e.cofield@jpl.nasa.gov

2021-132

Related News

Earth .

NASA-Led Study Pinpoints Areas of New York City Sinking, Rising

Mars .

Historic Wind Tunnel Facility Testing NASA’s Mars Ascent Vehicle Rocket

Earth .

Water-Watching Satellite Monitors Warming Ocean off California Coast

Solar System .

Venus on Earth: NASA’s VERITAS Science Team Studies Volcanic Iceland

Technology .

NASA to Discuss Optical Communications Demo Riding With Psyche

Climate Change .

NASA-Built Greenhouse Gas Detector Moves Closer to Launch

Mars .

NASA’s Oxygen-Generating Experiment MOXIE Completes Mars Mission

Earth .

NASA Scientists Test New Tool for Tracking Algal Blooms

Mars .

NASA, Partners Study Ancient Life in Australia to Inform Mars Search

Earth .

NASA Maps Key Heat Wave Differences in Southern California

Explore More

Image .

Hot Spots of Subsidence, Uplift in New York City

Image .

Map of New York City Subsidence and Uplift

Image .

SWOT Monitors Warming Waters Off California Coast

Mission .

Euclid

Image .

Methane Signal From Carbon Mapper Instrument Test

Image .

Imaging Spectrometer Fully Integrated

Image .

Imaging Spectrometer Inside Thermal Vacuum Chamber

Image .

Imaging Spectrometer Vacuum Chamber Test

Image .

Imaging Spectrometer Vibration Test

Image .

Channeled Scablands, Washington

About JPL
Who We Are
Executive Council
Directors
Careers
Internships
The JPL Story
JPL Achievements
Documentary Series
Annual Reports
JPL Plan: 2023-2026
Missions
Current
Past
Future
All
News
All
Earth
Solar System
Stars and Galaxies
Subscribe to JPL News
Galleries
Images
Videos
Audio
Podcasts
Apps
Visions of the Future
Slice of History
Robotics at JPL
Events
Lecture Series
Team Competitions
Speakers Bureau
Calendar
Visit
Public Tours
Virtual Tour
Directions and Maps
Topics
JPL Life
Solar System
Mars
Earth
Climate Change
Exoplanets
Stars and Galaxies
Robotics
More
Asteroid Watch
NASA's Eyes Visualizations
Universe - Internal Newsletter
Social Media
Get the Latest from JPL
Follow Us

JPL is a federally funded research and development center managed for NASA by Caltech.

More from JPL
Careers Education Science & Technology Acquisitions JPL Store
Careers
Education
Science & Technology
Acquisitions
JPL Store
Related NASA Sites
Basics of Spaceflight
Climate Kids
Earth / Global Climate Change
Exoplanet Exploration
Mars Exploration
Solar System Exploration
Space Place
NASA's Eyes Visualization Project
Voyager Interstellar Mission
NASA
Caltech
Privacy
Image Policy
FAQ
Feedback
Site Managers: Veronica McGregor, Randal Jackson
Site Editors: Tony Greicius, Naomi Hartono
CL#: 21-0018