New techniques in Space communication
March 19th 2008 08:12
Until recently communication techniques in space have evolved from those techniques already in use in current space-flight programs, and are closely related techniques developed in fields such as air-defense surveillance and radio astronomy. Basically, the same equations will govern the propagation of electromagnetic energy and the transmission of information in space as on the Earth.
The problem with radio communication is the large antenna arrays needed coupled with the large amount of radio energy output to get the signal to the spacecraft. Getting the signal to the space craft from earth is relatively easy. On earth you can construct huge antennas but in space you are limited to the weight and size of the spacecraft. You also have the limitation of bandwidth as it affects the rate of information you can send and receive. Currently communication data using radio can take many minutes and at times hours to transmit data, (planetary distance notwithstanding.)
A typical spacecraft will have about 50 watts of radio energy to transmit data to earth, (considerably less than a household light bulb). Imagine getting the radio energy from that light bulb say back to earth from Jupiter some 588 million km away and being able to extract picture and audio from such a weak signal is quite an achievement and an everyday occurrence, but we about to reach a limit in being able to maintain communication using radio over distances beyond our Solar system.
There is an alternative to using radio energy, Laser.
N.A.S.A states that by 2020 laser communication will be use.
Using laser technology for communication is more efficient for data transfers between earth and the spacecraft because lasers are capable of transferring huge amounts of data between planets due to larger amount of bandwidth. For example Mars could be mapped at 100 times the current rate.
The problem with radio communication is the large antenna arrays needed coupled with the large amount of radio energy output to get the signal to the spacecraft. Getting the signal to the space craft from earth is relatively easy. On earth you can construct huge antennas but in space you are limited to the weight and size of the spacecraft. You also have the limitation of bandwidth as it affects the rate of information you can send and receive. Currently communication data using radio can take many minutes and at times hours to transmit data, (planetary distance notwithstanding.)
Deep Space Tracking Station Canberra AU; Photo Carlcan
A typical spacecraft will have about 50 watts of radio energy to transmit data to earth, (considerably less than a household light bulb). Imagine getting the radio energy from that light bulb say back to earth from Jupiter some 588 million km away and being able to extract picture and audio from such a weak signal is quite an achievement and an everyday occurrence, but we about to reach a limit in being able to maintain communication using radio over distances beyond our Solar system.
There is an alternative to using radio energy, Laser.
shooting a laser at the galactic centre:ESO press photo 2007
N.A.S.A states that by 2020 laser communication will be use.
Using laser technology for communication is more efficient for data transfers between earth and the spacecraft because lasers are capable of transferring huge amounts of data between planets due to larger amount of bandwidth. For example Mars could be mapped at 100 times the current rate.
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