Newly Designed Antenna To Avoid Communication Blackouts In Spacecrafts
As the big space research organisations across the world get ready to launch their upcoming missions, scientists are gearing up to better the existing technologies to support the spacecrafts in their long journeys to and fro. A researcher duo from Harbin Institute of Technology in China have proposed a novel way of avoiding communication blackouts in spacecrafts which are re-entering the Earth's atmosphere. In a situation of such a barrier in communication, the current state or location of the spacecraft can not be found. It is said that the blackout in Apollo 13 lasted for more than a minute. One can only imaging the level of anxiety that must have prevailed during that period.
Xiaotian Gao and Binhao Jiang are colleagues at Harbin. They found that communication blackouts occur in hypersonic vehicles as they travel at a speed 5 times the speed of sound. When a spacecraft re-entes the Earth's atmosphere, it is engulfed in a cloud of hot ionized air (known as 'plasma sheath'), which reflects any electro-magnetic signals coming towards it and thus cuts off the spacecraft's communication with an external source.
An artist's concept of a spacecraft re-entering Earth's atmosphere as a plasma sheath surrounds it and cuts off communication signals with the ground.
The researcher duo found that in certain specific conditions, the same plasma sheath can be used to enhance the radiation from a communication antenna. That means they can essentially turn an enemy into a friend and put it to good use.
To test their theories, Gao and his research team figured that they could redesign the antenna to make it operable in those special conditions in an ordinary hypersonic flight. The signal enhancement in antenna could be achieved by electromagnetic oscillations between the plasma sheath and the surrounding air.
Therefore, they proposed the addition of a 'matched layer' (which acts like a capacitor) to these antennas so as to create the desired conditions with the plasma sheath (that acts like an inductor). Pairing them together, they get a resonant circuit.
For the resonance to work, the team had to make thickness of the matched layer and the plasma sheath smaller than the electromagnetic wavelength. To do that, they created an automatic control system for the match layer to adjust to the change in the properties of the plasma sheath.
Although this isn't the first time that researchers have attempted to avoid the communication blackouts, the matched layer approach does have significant advantages over existing solutions.
For instance, the equipment to be installed is lighter, doesn't need extra energy to operate, doesn't need a particular shape of vehicle to work and as stated earlier, can adapt to the change of plasma sheath's properties.
What are your thoughts about the newly proposed re-designed antenna system? Share with us in comments below.
Source: Communicating with Hypersonic Vehicles in Flight | American Institute of Physics
Xiaotian Gao and Binhao Jiang are colleagues at Harbin. They found that communication blackouts occur in hypersonic vehicles as they travel at a speed 5 times the speed of sound. When a spacecraft re-entes the Earth's atmosphere, it is engulfed in a cloud of hot ionized air (known as 'plasma sheath'), which reflects any electro-magnetic signals coming towards it and thus cuts off the spacecraft's communication with an external source.
An artist's concept of a spacecraft re-entering Earth's atmosphere as a plasma sheath surrounds it and cuts off communication signals with the ground.
To test their theories, Gao and his research team figured that they could redesign the antenna to make it operable in those special conditions in an ordinary hypersonic flight. The signal enhancement in antenna could be achieved by electromagnetic oscillations between the plasma sheath and the surrounding air.
Therefore, they proposed the addition of a 'matched layer' (which acts like a capacitor) to these antennas so as to create the desired conditions with the plasma sheath (that acts like an inductor). Pairing them together, they get a resonant circuit.
For the resonance to work, the team had to make thickness of the matched layer and the plasma sheath smaller than the electromagnetic wavelength. To do that, they created an automatic control system for the match layer to adjust to the change in the properties of the plasma sheath.
Although this isn't the first time that researchers have attempted to avoid the communication blackouts, the matched layer approach does have significant advantages over existing solutions.
For instance, the equipment to be installed is lighter, doesn't need extra energy to operate, doesn't need a particular shape of vehicle to work and as stated earlier, can adapt to the change of plasma sheath's properties.
What are your thoughts about the newly proposed re-designed antenna system? Share with us in comments below.
Source: Communicating with Hypersonic Vehicles in Flight | American Institute of Physics
Replies
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saikrish87Re-entry crew module is a very interesting application in Aersopace. Very few countries posses this technology and more and more developing countries are trying for a break through in mastering this technology. As mentioned by Ankita the main factors 1) extreme temperature at the reentry time 2)Extreme velocity of more than 5 Km/Sec 3) different atmospheric levels, make experimenting this technology very hard.
Though i am not a communications expert, I would like to comment on one technology being researched that might follow the same method. But before that we could see some importance of this.
We might all be aware that soon ISRO is also planning to launch its own ingeniously (May be with some Russian help) made reentry vehicle for using space crafts multiple times rather than discarding it after every launch to cut down costs and explore this technology. Recently Elon Musk's SpaceX has done some awesome feat by almost bringing back the launch vehicle back to earth after injecting the satellite in its orbit. The Russians build the Buran in 1970s and made a great break through in reentry AD and completely automating the complete flight of Buran. The Americans too have their own part in this success but after the Colombia shuttle disaster there has been a stop. So, why are these countries/companies trying to venture into this technology and where this technology would lead human kind to? these are the questions we would ask..
I strongly believe that mankind will leave our solar system in search of life in other planet or even to search for better earths (after we destroy ourselves/destroyed by aliens visiting us) in near future may be long also. As shown in science fiction movies like one my favorite "The Interstellar" we need to land in planet with a very harsh atmosphere with unknown conditions so we need the best ships, with best stability, controls, dynamics and on board payload systems for communication. So we need to master this technology in earth so that we could master it elsewhere in the universe.
Well coming to the topic of communication by the redesigned antenna. I would like to say that the plasma heat sheild will reflect the EM radiation and deflect it away so the black out occurs. I also read that under special condition the plasma sheath can enhance the communication. This is nothing but the EM radiation.
Here i would like to bring out one interesting research on Superconductivity which scientist have found that under superconductivity the radiation force can be multiplied many times and this can be in turn used to increase the EM radiation like light or any wave for that matter. This technology could be used for spacecraft travelling in heliocentric trajectory where the SRP (Solar radiation pressure) exerts translation and rotational force on the spacecraft and making the spacecraft deviate from its trajectory. So May be this could be employed but the point is how. All said this requires lot of research and breakthrough would be great.
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