How Can Atomic Clocks Help Humans Arrive On Mars On Time?

Autonomous Navigation - Overcoming Technological Limitations

NASA navigators are assisting in the development of a future in which spacecraft may safely and independently travel to destinations such as the Moon and Mars.

• Today, navigators guide a spacecraft by calculating its position from Earth and transmitting the data to space in a two-way relay system that may take minutes to hours to give instructions. 

• This mode of navigation ensures that our spacecraft remain connected to the earth, waiting for instructions from our planet, no matter how far a mission goes across the solar system.

• This constraint will obstruct any future crewed voyage to another planet. 

How can astronauts travel to destinations distant from Earth if they don't have direct control over their path? 

And how will they be able to land properly on another planet if there is a communication delay that slows down their ability to alter their trajectory into the atmosphere?

The Deep Space Atomic Clock, a toaster-sized clock developed by NASA, seeks to provide answers to these concerns. 

• It's the first GPS-like device that's tiny enough to go on a spaceship and steady enough to operate. 

• The technological demonstrated allows the spaceship to determine its location without relying on data from Earth.

• The clock will be sent into Earth's orbit for a year in late June on a SpaceX Falcon Heavy rocket, where it will be tested to see whether it can assist spacecraft in locating themselves in space.

If the Deep Orbit Atomic Clock's first year in space goes well, it may open the way for one-way navigation in the future, when humans can be led over the Moon's surface by a GPS-like system or safely fly their own missions to Mars and beyond.

• Navigators on Earth guide every spaceship traveling to the furthest reaches of the universe. 

• By allowing onboard autonomous navigation, or self-driving spaceship, the Deep Space Atomic Clock will alter that.

Deep Space Navigation

Atomic clocks in space are not a novel concept. 

• Every GPS gadget and smartphone uses atomic clocks on satellites circling Earth to calculate its position. 

• Satellites transmit signals from space, and the receiver triangulates your location by calculating the time it takes for the signals to reach your GPS.

• At the moment, spacecraft beyond Earth's orbit do not have a GPS to help them navigate across space. 

GPS satellites' atomic clocks aren't precise enough to transmit instructions to spacecraft, where even a fraction of a second may mean missing a planet by kilometers.

• Instead, navigators transmit a signal to the spaceship, which bounces it back to Earth, using massive antennas on Earth.

• Ground-based clocks keep track of how long it takes the signal to complete this two-way trip. 

• The length of time informs them how far away and how quickly the spaceship is traveling. 

• Only then will navigators be able to give the spacecraft instructions, instructing it where to travel.

• "It's the same idea as an echo," Seubert said. "If I scream in front of a mountain, the longer it takes for the echo to return to me, the farther away the mountain is."

Two-way navigation implies that a mission must wait for a signal containing instructions to traverse the enormous distances between planets, no matter how far into space it travels. 

• It's a procedure made famous by Curiosity's arrival on Mars, when the world waited 14 minutes for the rover to transmit the word that it had landed safely with mission headquarters. 

• A one-way communication between Earth and Mars may take anything from 4 to 20 minutes to get between the planets, depending on where they are in their orbits.

• It's a sluggish, arduous method of navigating deep space, one that clogs up NASA's Deep Space Network's massive antennae like a busy phone line. 

• A spaceship traveling at tens of thousands of kilometers per hour may be at a completely different location by the time it "knows" where it is during this interaction.

Atomic Clocks To Compute Precise Locations In Space

This two-way system may be replaced with an atomic clock small enough to go on a mission but precise enough to provide correct instructions. 

• A signal would be sent from Earth to a spaceship in the future. 

• The Deep Space Atomic Clock aboard, like its Earthly counterparts, would measure the time it took for that signal to reach it. 

• After that, the spacecraft could compute its own location and course, effectively directing itself.

Having a clock aboard would allow onboard radio navigation, which, when coupled with optical navigation, would provide astronauts with a more precise and safe method to navigate themselves.

• This one-way navigation technique may be used on Mars and beyond. 

• By sending a single signal into space, DSN antennas would be able to connect with many missions at the same time. 

• The new technique has the potential to enhance GPS accuracy on Earth. 

• Additionally, several spacecraft equipped with Deep Space Atomic Clocks might circle Mars, forming a GPS-like network that would guide robots and people on the surface.

The Deep Space Atomic Clock will be able to assist in navigation not just on Earth, but also on distant planets. Consider what would happen if we had GPS on other planets.

• Burt and JPL clock scientists Robert Tjoelker and John Prestage developed a mercury ion clock that, like refrigerator-size atomic clocks on Earth, retains its stability in space. 

• The Deep Space Atomic Clock was shown to be 50 times more accurate than GPS clocks in lab testing. Every ten million years, there is a one-second mistake.

• The clock's ability to stay steady in orbit will be determined by its demonstration in space. 

• A Deep Space Atomic Clock may launch on a mission as early as the 2030s if it succeeds. 

• The first step toward self-driving spaceship capable of transporting people to distant planets.

General Atomics Electromagnetic Systems of Englewood, Colorado supplied the spacecraft for the Deep Space Atomic Clock. 

It is supported by NASA's Space Technology Mission Directorate's Technology Demonstration Missions program and NASA's Human Exploration and Operations Mission Directorate's Space Communications and Navigations program. The project is overseen by JPL.

~ Jai Krishna Ponnappan

Courtesy - NASA.gov

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