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Number Won 2019. 9. 12. 11:44
June 4, 2019

Five Things to Know about NASA's Deep Space Atomic Clock

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.
Artist's concept of atomic clock
An animated image of the Deep Space Atomic Clock, a new technology being tested by NASA that will change the way humans navigate the solar system. The precise timekeeper is targeted to launch from Florida in late June, aboard a SpaceX Falcon Heavy rocket.
Credits: NASA/JPL-Caltech
Technicians working on the atomic clock
Technicians integrate NASA's Deep Space Atomic Clock into the Orbital Test Bed Earth-orbiting satellite, which will launch on a SpaceX Falcon Heavy rocket, in late June.
Credits: General Atomics

Editor’s Note: Updated June 14, 2019, to revise an estimate of the clock's stability.

NASA is sending a new technology to space in late June that will change the way we navigate our spacecraft — even how we send astronauts to Mars and beyond. Built by NASA's Jet Propulsion Laboratory in Pasadena, California, the Deep Space Atomic Clock is a technology demonstration that will help spacecraft navigate autonomously through deep space. No larger than a toaster oven, the instrument will be tested in Earth orbit for one year, with the goal of being ready for future missions to other worlds.

Here are five key facts to know about NASA's Deep Space Atomic Clock:

It works a lot like GPS

The Deep Space Atomic Clock is a sibling of the atomic clocks you interact with every day on your smart phone. Atomic clocks aboard satellites enable your phone's GPS application to get you from point A to point B by calculating where you are on Earth, based on the time it takes the signal to travel from the satellite to your phone.

But spacecraft don't have GPS to help them find their way in deep space; instead, navigation teams rely on atomic clocks on Earth to determine location data. The farther we travel from Earth, the longer this communication takes. The Deep Space Atomic Clock is the first atomic clock designed to fly onboard a spacecraft that goes beyond Earth's orbit, dramatically improving the process.  

It will help our spacecraft navigate autonomously

Today, we navigate in deep space by using giant antennas on Earth to send signals to spacecraft, which then send those signals back to Earth. Atomic clocks on Earth measure the time it takes a signal to make this two-way journey. only then can human navigators on Earth use large antennas to tell the spacecraft where it is and where to go.

If we want humans to explore the solar system, we need a better, faster way for the astronauts aboard a spacecraft to know where they are, ideally without needing to send signals back to Earth. A Deep Space Atomic Clock on a spacecraft would allow it to receive a signal from Earth and determine its location immediately using an onboard navigation system.

It loses only 1 second in 10 million years

Any atomic clock has to be incredibly precise to be used for this kind of navigation: A clock that is off by even a single second could mean the difference between landing on Mars and missing it by miles. In ground tests, the Deep Space Atomic Clock proved to be up to 50 times more stable than the atomic clocks on GPS satellites. If the mission can prove this stability in space, it will be one of the most precise clocks in the universe.

It keeps accurate time using mercury ions

Your wristwatch and atomic clocks keep time in similar ways: by measuring the vibrations of a quartz crystal. An electrical pulse is sent through the quartz so that it vibrates steadily. This continuous vibration acts like the pendulum of a grandfather clock, ticking off how much time has passed. But a wristwatch can easily drift off track by seconds to minutes over a given period.

An atomic clock uses atoms to help maintain high precision in its measurements of the quartz vibrations. The length of a second is measured by the frequency of light released by specific atoms, which is same throughout the universe. But atoms in current clocks can be sensitive to external magnetic fields and temperature changes. The Deep Space Atomic Clock uses mercury ions — fewer than the amount typically found in two cans of tuna fish — that are contained in electromagnetic traps. Using an internal device to control the ions makes them less vulnerable to external forces.

It will launch on a SpaceX Falcon Heavy rocket

The Deep Space Atomic Clock will fly on the Orbital Test Bed satellite, which launches on the SpaceX Falcon Heavy rocket with around two dozen other satellites from government, military and research institutions. The launch is targeted for June 22, 2019, at 8:30 p.m. PDT (11:30 p.m. EDT) from NASA's Kennedy Space Center in Florida and will be live-streamed here:

https://www.nasa.gov/live

The Deep Space Atomic Clock is hosted on a spacecraft provided by General Atomics Electromagnetic Systems of Englewood, Colorado. It is sponsored by the Technology Demonstration Missions program within NASA's Space Technology Mission Directorate and the Space Communications and Navigations program within NASA's Human Exploration and Operations Mission Directorate. The project is managed by JPL.


Aug. 27, 2019

NASA Activates Deep Space Atomic Clock

NASA's Deep Space Atomic Clock
NASA's Deep Space Atomic Clock, the first GPS-like technology for deep space, started its one-year space mission on Friday. If the technology demonstration proves successful, similar atomic clocks will be used to navigate the self-flying spacecraft.
Credits: General Atomics Electromagnetic Systems

An atomic clock that could pave the way for autonomous deep space travel was successfully activated last week and is ready to begin its year-long tech demo, the mission team confirmed on Friday, Aug. 23, 2019. Launched in June, NASA's Deep Space Atomic Clock is a critical step toward enabling spacecraft to safely navigate themselves in deep space rather than rely on the time-consuming process of receiving directions from Earth.

Developed at NASA's Jet Propulsion Laboratory in Pasadena, California, the clock is the first timekeeper stable enough to map a spacecraft's trajectory in deep space while being small enough to fly onboard the spacecraft. A more stable clock can operate farther from Earth, where it needs to work well for longer periods than satellites closer to home.

Atomic clocks, like those used in GPS satellites, are used to measure the distance between objects by timing how long it takes a signal to travel from Point A to Point B. For space exploration, atomic clocks must be extremely precise: an error of even one second means the difference between landing on a planet like Mars or missing it by hundreds of thousands of miles. Up to 50 times more stable than the atomic clocks on GPS satellites, the mercury-ion Deep Space Atomic Clock loses one second every 10 million years, as proven in controlled tests on Earth. Now it will test that accuracy in space.

Navigators currently use refrigerator-size atomic clocks on Earth to pinpoint a spacecraft's location. Minutes to hours can go by as a signal is sent from Earth to the spacecraft before being returned to Earth, where it is used to create instructions that are then sent back to the spacecraft. A clock aboard a spacecraft would allow the spacecraft to calculate its own trajectory, instead of waiting for navigators on Earth to send that information. This advancement would free missions to travel farther and, eventually, carry humans safely to other planets.

"The goal of the space experiment is to put the Deep Space Atomic Clock in the context of an operating spacecraft — complete with the things that affect the stability and accuracy of a clock — and see if it performs at the level we think it will: with orders of magnitude more stability than existing space clocks," said navigator Todd Ely, principal investigator of the project at JPL.

In coming months, the team will measure how well the clock keeps time down to the nanosecond. The results begin the countdown to a day when technology can safely help astronauts navigate themselves to other worlds.

The Deep Space Atomic Clock is hosted on a spacecraft provided by General Atomics Electromagnetic Systems of Englewood, Colorado. It is sponsored by the Technology Demonstration Missions program within NASA's Space Technology Mission Directorate and the Space Communications and Navigations program within NASA's Human Exploration and Operations Mission Directorate. JPL manages the project.

Arielle Samuelson
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307
arielle.a.samuelson@jpl.nasa.gov

2019-174

Last Updated: Aug. 28, 2019
Editor: Tony Greicius


Read more about the Deep Space Atomic Clock here:

https://www.nasa.gov/mission_pages/tdm/clock/index.html

Learn about the other NASA technologies on the SpaceX Falcon Heavy launch here:

https://www.nasa.gov/spacex

Arielle Samuelson
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307
arielle.a.samuelson@jpl.nasa.gov

Last Updated: June 18, 2019
Editor: Tony Greicius