NASA has switched on a new, high-precision, space-based atomic clock, which the agency hopes will one day help spacecraft move through space without relying on earth-bound clocks.
DSAC), and it measures the behavior of mercury ions trapped in its small frame. It has been in orbit since June, but was successfully activated on August 23 for the first time. It's not at all conspicuous – just a gray box the size of a four-slice toaster and full of wires, Jill Seubert, an aerospace engineer and one of the project's supervisors at NASA, Live Science said. But this modest size is the point: Suebert and her colleagues are working to construct a clock that is small enough to be loaded onto each spaceship and accurate enough to handle complicated maneuvers in space without input from their refrigerator-sized relatives on earth.
You need an accurate watch to navigate space, because it's big and empty. There are few landmarks that you can use to gauge your position or speed, and most are too far away to provide accurate information. Any decision to turn a ship or fire its engines begins with three questions: Where am I? How fast do I move? And in which direction?
Related: The 1
The best way to answer these questions is to look at objects for which the answers are already known; Radio transmitters on Earth or GPS satellites following known orbits through space. Send a signal at the speed of light with the exact time at point A and measure how long it takes for point B to be reached. This shows you the distance between A and B. Send two more signals from two more locations, and you have enough information to find out exactly where point B is in three-dimensional space. (This is how your phone's GPS software works by constantly checking the tiny differences in the time signatures sent by various orbiting satellites.)
NASA is currently relying on a similar but not so much space-based navigation exact system, so Seubert. Most atomic clocks and transmitters are located on Earth and together form the so-called Deep Space Network. Therefore, NASA can not normally calculate the position and speed of a spacecraft from three sources at once. Instead, the agency uses a series of measurements in which both the earth and the spacecraft move through space over time to determine the direction and position of the spacecraft.
For a spacecraft to know where it is, it must receive a signal from the depth of space network, calculate the time until the signal arrives, and determine the distance based on the speed of light. "To do this very carefully, you need to be able to measure those times – the signal's transmission and reception times – as accurately as possible, and on-site, when we send those signals from our Deep Space Network, we have Atomic clocks that are very accurate and accurate, "said Seubert. "So far, the clocks we've had are small enough and low-power enough to fly with a spaceship, they're called ultra-stable oscillators, which is a completely misnomer, they're not ultrastructural, they record that signal." Time preserved, but very inaccurate.
Because the position data aboard the spacecraft is so unreliable It is much more complicated to figure out how to navigate-for example, when to turn on an engine or change course-in other words, people on Earth are propelling the spaceship at a distance of hundreds of thousands or millions of miles.
"But if you could accurately record the signal time received on board with an atomic clock, you now have the opportunity to gather all this tracking data on board and design your computer and your radio so that the spaceship will drive itself can, "she said.
NASA and other space agencies have previously set up atomic clocks in space – our entire GPS satellite fleet ranks atomic clocks. But for the most part, they are too inaccurate and unwieldy for long-term work, Seubert said. The environment in space is much rougher than a research lab on Earth. Temperatures change when the clocks go in and out in sunlight. The radiation values rise and fall.
"It is a well-known space problem, and we usually ship radiation-cured parts that we have shown to work in different radiation environments with similar performance," she said.
However, the radiation is still changing the way the electronics work. And these changes affect the sensitive devices that allow atomic clocks to measure the lapse of time and threaten to introduce inaccuracies. Seubert pointed out that the Luftwaffe uploads corrections to the clocks of the GPS satellites several times a day to prevent them from being synchronized with the clocks on the ground system, which is not only portable and easy enough to carry on any spacecraft but it is also robust enough to be operated in space in the long term, without the need for continual adjustments by teams on Earth.
In addition to a more precise navigation in space With terrestrial signals, such a watch could one day cause astronauts to run around on remote outposts, as we do with our mapping equipment on Earth, Seubert said. A small fleet of satellites equipped with DSAC equipment could orbit the Moon or Mars and operate in place of terrestrial GPS systems, and this network would not have to be corrected several times a day.
On the road, she said, DSACs or similar devices could play a role in pulsar navigation systems that track the timing of things like the pulsing of light from other star systems so that spaceships can navigate without inputs from the Earth.
For the next year, however, the goal is to make this first DSAC work properly as it circles around the Earth.
"What we need to do is basically learn how to set the clock to work properly in this environment," Seubert said.
Lessons learned by the DSAC crew during device tuning this year should prepare them to use similar devices on longer range missions on the road, she added.
Originally published on Live Science .