The next era of NASA's Remote Space Network (DSN) lies in the field of X-rays and lasers.
Testing of space optical laser communications will begin next year, X-ray navigation and communications systems are in the process of development.
70-meter antenna in Goldstone. Source: NASA / JPL
After half a century of using radio to track and communicate with all devices, from the first lunar Rangers to the Voyager probes, now crossing the solar system boundary and leaving for interstellar space, NASA is investing $ 2 billion in optical and x-ray network spectrum.
Next year, NASA plans to launch a demo flight to test optical laser communications for the LADEE mission on the moon (Lunar Atmosphere and Dust Environment Explorer - a program to study the lunar atmosphere and the dust environment of its orbit). And optical missions will soon follow to test the capabilities of a laser transponder in a geostationary earth orbit (GEO).
')
“DSN works almost flawlessly, doing everything we ask for,” said Leslie Deutsch, chief process engineer of the NASA Interplanetary Networks Office. “There were no cases when space missions were lost when calling via DSN, but in several cases DSN was used to save the mission.”
Using three ground complexes: Goldstone, California; Canberra, Australia; and Madrid, Spain, - DSN tracks about 35 spacecraft with success exceeding 98 percent.
But from time to time NASA uses other radio telescopes. Doytch notes that with the recent landing of the Mars Science Lab (Mars Science Lab), the Parkers DSN DSN in Australia was used as a backup capability to track MSL signals during entry, descent and landing on Mars.
“We have bottlenecks in that tools on Mars could return more data if we had more powerful communication channels,” said Deutsch.
Wherever there is a lot of research, says Deutsch, it’s also sensible to create GPS-like capabilities to help navigate the surface of the planet. Doytch notes that the GPS capability for Mars is still being studied and possibly being implemented in the coming decades.
Meanwhile, NASA will experience laser communications. LLCD (Lunar Laser Communications Demonstration - demonstration of laser communication with the Moon) will be launched from LADEE in January next year and will demonstrate the speed of a laser transmission line from the Moon at 622 megabytes [per second].
Then at the end of 2017, a laser relay demonstration project (LCRD - the Laser Communications Relay Demonstration Project) will be launched in cooperation with the Space Systems / Loral commercial satellite. From geostationary orbit, LCRD will continuously experience high-speed data transmission using optical communication for two years.
LCRD will use 0.5W lasers; which roughly corresponds to the current capacity when burning DVDs. But increasing this figure to just 5 watts will allow LCRD technology to provide a link with an outgoing speed of 1 gigabyte per second and an incoming speed of 100 megabytes per second in earth orbit. This is 10 to 100 times faster than DSN is now provided on radio frequencies.
“We need an optical repeater in geostationary orbit by 2022,” says David Israel, NASA's space communications engineer at the Goddard Space Flight Center.
Although Israel claims that NASA will use “eye-safe” wavelengths and ensure that their lasers never cross the path of an airplane or satellite, it notes that the usual technical problem for optical communications is conventional clouds.
So, when looking for a place for ground-based optical receivers, why not just go to areas where the sky is almost always clear?
“The gorgeous reception on some isolated mountain tops is perfect for astronomy,” said Israel. “But if you have a high data transfer rate from orbit there, then there may not be a [efficient] way to get this data from the mountain.”
Thus, one of the problems for ground-based optical communication telescopes is to strike a balance between optimal “visibility” and the use of existing communication infrastructure lines needed to quickly redirect incoming data back to remote researchers.
NASA is also exploring the suitability of natural astrophysical x-ray sources to create a space navigation system that would function on a solar scale similar to GPS. The idea is to use [accreting millisecond] pulsars, rotating neutron stars, emitting X-rays at intervals of a millisecond, to accurately determine the ship's course and position.
Voyager 1 Source: NASA / JPL
“The XNAV system,” says Keith Gendreau, an astrophysicist at NASA’s Space Flight Center in Goddard, “will need a tracking X-ray detector to observe several pulsars over time.”
“Pulsars produce regular impulses that can compete in accuracy with the atomic clock for several months and years,” said Gendreau. - GPS is a grouping of satellites, each of which contains an atomic clock that transmits exact time. GPS receivers receive time signals from several satellites, and from this data they calculate their coordinates. For XNAV, our watches will be pulsars distributed on a galactic scale, which will provide GPS navigation both throughout the Solar System and beyond. ”
Today, to navigate to the outer planets, use of the system of remote space communications and spacecraft on-board star sensors to calculate the exact position. But Doech says XNAV can make autonomous spacecraft navigation even more accurate.
“XNAV would create 3-dimensional positional data from pulsars in different directions in the sky,” says Gendreau. He also notes that in addition to the three pulsars that the spacecraft will use to determine its position, the fourth pulsar will provide independent measurements of time.
The researcher of the internal structure of neutron stars - (NICER - Neutron Star Interior Composition Explorer) is an experiment proposed by NASA for the timing of pulsars that could demonstrate XNAV by the end of 2016.
“By the time the miners go into space in the asteroid belt, it's safe to say that they will use XNAV,” Israel said.
Meanwhile, NASA researchers at Goddard are also working on an X-ray connection (XCOM), which uses photo-electric modulation of the photocathode using an ultraviolet source for communication. The advantage of X-rays over laser coupling is that the X-ray wavelength is shorter and it can penetrate areas that are inaccessible to radio and optical frequencies, for example, when entering the atmosphere.
Gendreau says that one of the main advantages of X-rays in front of lasers is that the short wavelength allows you to transmit very thin rays, and therefore lose much less energy when communicating at long distances.
“The very high energy of X-rays can also penetrate the plasma envelope surrounding the capsule entering the atmosphere and provide a connection with a low data transfer rate for such a hypersonic device,” said Gendreau. “If NICER takes off, then by 2018 we could use it as a receiver for the first XCOM demonstration in space.”
What is the future of the Remote Space Network?
Doytch speaks about data transfer speeds much higher than today; continuous DSN coverage for people in remote areas such as the far side of the moon, as well as Internet-like empowerment where NASA sends astronauts or cars.
What about the radio?
“I think that space radiocommunication can never be completely withdrawn,” said Deutsch. “It's very simple and easy.”
70-meter antenna in Goldstone. Source: NASA / JPL
After half a century of using radio to track and communicate with all devices, from the first lunar Rangers to the Voyager probes, now crossing the solar system boundary and leaving for interstellar space, NASA is investing $ 2 billion in optical and x-ray network spectrum.
Next year, NASA plans to launch a demo flight to test optical laser communications for the LADEE mission on the moon (Lunar Atmosphere and Dust Environment Explorer - a program to study the lunar atmosphere and the dust environment of its orbit). And optical missions will soon follow to test the capabilities of a laser transponder in a geostationary earth orbit (GEO).
')
“DSN works almost flawlessly, doing everything we ask for,” said Leslie Deutsch, chief process engineer of the NASA Interplanetary Networks Office. “There were no cases when space missions were lost when calling via DSN, but in several cases DSN was used to save the mission.”
Using three ground complexes: Goldstone, California; Canberra, Australia; and Madrid, Spain, - DSN tracks about 35 spacecraft with success exceeding 98 percent.
But from time to time NASA uses other radio telescopes. Doytch notes that with the recent landing of the Mars Science Lab (Mars Science Lab), the Parkers DSN DSN in Australia was used as a backup capability to track MSL signals during entry, descent and landing on Mars.
“We have bottlenecks in that tools on Mars could return more data if we had more powerful communication channels,” said Deutsch.
Wherever there is a lot of research, says Deutsch, it’s also sensible to create GPS-like capabilities to help navigate the surface of the planet. Doytch notes that the GPS capability for Mars is still being studied and possibly being implemented in the coming decades.
Meanwhile, NASA will experience laser communications. LLCD (Lunar Laser Communications Demonstration - demonstration of laser communication with the Moon) will be launched from LADEE in January next year and will demonstrate the speed of a laser transmission line from the Moon at 622 megabytes [per second].
Then at the end of 2017, a laser relay demonstration project (LCRD - the Laser Communications Relay Demonstration Project) will be launched in cooperation with the Space Systems / Loral commercial satellite. From geostationary orbit, LCRD will continuously experience high-speed data transmission using optical communication for two years.
LCRD will use 0.5W lasers; which roughly corresponds to the current capacity when burning DVDs. But increasing this figure to just 5 watts will allow LCRD technology to provide a link with an outgoing speed of 1 gigabyte per second and an incoming speed of 100 megabytes per second in earth orbit. This is 10 to 100 times faster than DSN is now provided on radio frequencies.
“We need an optical repeater in geostationary orbit by 2022,” says David Israel, NASA's space communications engineer at the Goddard Space Flight Center.
Although Israel claims that NASA will use “eye-safe” wavelengths and ensure that their lasers never cross the path of an airplane or satellite, it notes that the usual technical problem for optical communications is conventional clouds.
So, when looking for a place for ground-based optical receivers, why not just go to areas where the sky is almost always clear?
“The gorgeous reception on some isolated mountain tops is perfect for astronomy,” said Israel. “But if you have a high data transfer rate from orbit there, then there may not be a [efficient] way to get this data from the mountain.”
Thus, one of the problems for ground-based optical communication telescopes is to strike a balance between optimal “visibility” and the use of existing communication infrastructure lines needed to quickly redirect incoming data back to remote researchers.
NASA is also exploring the suitability of natural astrophysical x-ray sources to create a space navigation system that would function on a solar scale similar to GPS. The idea is to use [accreting millisecond] pulsars, rotating neutron stars, emitting X-rays at intervals of a millisecond, to accurately determine the ship's course and position.
Voyager 1 Source: NASA / JPL
“The XNAV system,” says Keith Gendreau, an astrophysicist at NASA’s Space Flight Center in Goddard, “will need a tracking X-ray detector to observe several pulsars over time.”
“Pulsars produce regular impulses that can compete in accuracy with the atomic clock for several months and years,” said Gendreau. - GPS is a grouping of satellites, each of which contains an atomic clock that transmits exact time. GPS receivers receive time signals from several satellites, and from this data they calculate their coordinates. For XNAV, our watches will be pulsars distributed on a galactic scale, which will provide GPS navigation both throughout the Solar System and beyond. ”
Today, to navigate to the outer planets, use of the system of remote space communications and spacecraft on-board star sensors to calculate the exact position. But Doech says XNAV can make autonomous spacecraft navigation even more accurate.
“XNAV would create 3-dimensional positional data from pulsars in different directions in the sky,” says Gendreau. He also notes that in addition to the three pulsars that the spacecraft will use to determine its position, the fourth pulsar will provide independent measurements of time.
The researcher of the internal structure of neutron stars - (NICER - Neutron Star Interior Composition Explorer) is an experiment proposed by NASA for the timing of pulsars that could demonstrate XNAV by the end of 2016.
“By the time the miners go into space in the asteroid belt, it's safe to say that they will use XNAV,” Israel said.
The most accurate clocks in nature can make the Galactic GPS possible. (Illustration from Wikipedia)
The radio search discovered 17 new millisecond pulsars by examining a list of unidentified sources received by the Fermi gamma telescope. The colored circles indicate the positions of the new pulsars discovered in 2009, during the telescope year of operation, on the overview map of the whole sky.
Meanwhile, NASA researchers at Goddard are also working on an X-ray connection (XCOM), which uses photo-electric modulation of the photocathode using an ultraviolet source for communication. The advantage of X-rays over laser coupling is that the X-ray wavelength is shorter and it can penetrate areas that are inaccessible to radio and optical frequencies, for example, when entering the atmosphere.
Gendreau says that one of the main advantages of X-rays in front of lasers is that the short wavelength allows you to transmit very thin rays, and therefore lose much less energy when communicating at long distances.
“The very high energy of X-rays can also penetrate the plasma envelope surrounding the capsule entering the atmosphere and provide a connection with a low data transfer rate for such a hypersonic device,” said Gendreau. “If NICER takes off, then by 2018 we could use it as a receiver for the first XCOM demonstration in space.”
What is the future of the Remote Space Network?
Doytch speaks about data transfer speeds much higher than today; continuous DSN coverage for people in remote areas such as the far side of the moon, as well as Internet-like empowerment where NASA sends astronauts or cars.
What about the radio?
“I think that space radiocommunication can never be completely withdrawn,” said Deutsch. “It's very simple and easy.”
Source: https://habr.com/ru/post/155519/
All Articles