NASA has included a new, super-precision, space-based atomic clock that the agency hopes will one day help spacecraft navigate deep space without relying on earth clocks.
It is called the Deep Space Atomic Clock (DSAC) and works by measuring the behavior of mercury ions trapped in its small frame. It has been in orbit since June but was first successfully activated on 23 August. It's not intrusive at all – just a gray, four-slice toaster box full of wires, Jill Siebert, a space engineer and one of NASA's project managers, told Live Science. But this unimaginable size is the point: Siebert and her colleagues work to create a clock small enough to load on any spacecraft and accurate enough to run complex maneuvers in deep space without any contribution from cousins the size of a refrigerator on the ground.
You need an accurate clock to navigate the space because it is large and empty. There are few guidelines to judge your position or speed, and most are too far away to provide accurate information. So any decision to spin a ship or ignite its driving forces, Siebert said, begins with three questions: Where am I? How fast do I move? And in what direction?
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The best way to answer these questions is to look at objects for which answers are already known as radio transmitters on Earth or GPS satellites following known orbits in space. Send a light speed signal at the exact time at point A and measure how long it takes to get to point B. This tells you the distance between A and B. Send two more signals from two more places and you'll have enough information to know where exactly is point B in three-dimensional space. (This is how GPS software works on your phone: by continuously checking the minute differences in time signatures transmitted by different orbiting satellites.)
NASA is currently relying on a similar, but not so precise, space-based orientation. system, Subert said. Most of the atomic clocks and broadcasting equipment are on Earth and collectively form what is known as the Deep Space Network. So NASA usually can't calculate the position and speed of a spacecraft from three sources in one go. Instead, the agency uses a series of measurements as Earth and the spacecraft move through space over time to hammer the direction and position of the spacecraft.
For a spacecraft to know where it is, it must receive a signal from the deep Space Network, calculate the time it takes for the signal to arrive, and use the speed of light to determine the distance. "To do this very accurately, you have to be able to measure those times – the times sent and received by the signal – as accurately as possible. And on earth, when we send these signals from our deep space network, we have atomic clocks that are very precise and accurate, "Siebert said. "So far, the clocks we have are small enough and low power to fly a spacecraft, they are called ultrastable oscillators, which is totally wrong. They are not ultra-stable. They record this signal – get time, but it's with very low accuracy. "
As data for the location of the spacecraft is astounding First unreliable, inventing how to move – when to turn the traction or change course – for example, is much more complicated and must be done on Earth. In other words, humans on Earth run a spacecraft for hundreds of thousands or millions of miles.
"But if you could record the time received from the signal very accurately with an atomic clock, you now have the ability to collect all this tracking data on board and design your computer and radio so that the spacecraft can control itself ", she said.
NASA and other space agencies have put atomic clocks in space before. Our entire GPS satellite fleet wears atomic clocks. But for the most part, they are too inaccurate and inconvenient for long-term work, Siebert said. The environment in space is much rougher than a lab for Earth exploration. Temperatures change as the clocks pass in and out of sunlight.
"This is a well-known problem with space flight and we usually send radiation-hardened parts that we can demonstrate can work in different radiation environments with similar characteristics," she said.
But radiation still changes the way electronics work. And these changes affect the sensitive equipment that atomic clocks use to measure time sliding, threatening to introduce inaccuracies. Several times a day, Seubert pointed out, the Air Force uploads adjustments to GPS satellites to ensure that it does not deviate from clocking on the ground.
The purpose of DSAC is to establish a system that is not only portable and simple enough to be installed on any spacecraft, but also durable enough to operate in space over the long term without requiring permanent ground based adjustments teams.
In addition to allowing more precise navigation in deep spaces using ground signals, such a clock can one day allow astronauts in distant stands to travel just like we do with our Earth mapping devices, Siebert said. A small fleet of satellites equipped with DSAC devices can orbit the moon or Mars, functioning instead of terrestrial GPS systems, and this network will not require adjustments several times a day.
On the way down the road, she said, DSACs or similar devices could play a role in pulsar navigation systems that would track the time of things like the pulsation of light from other star systems to allow spacecraft to move without no entrance from Earth.
However, for the next year, the goal is to get this first DSAC to function properly as it orbits near Earth.
"What we have to do is essentially learn how to set the clock to work properly in this environment," Siebert said.
The lessons the DSAC team learns while setting up the device this year should prepare them to use similar devices for longer-range missions, she added.
Originally published by Live Science .