Monday, September 26, 2011

NASA Laser-based communications Internet

Impatient internet users will soon be able to download high definition images from space in few minutes if a newly approved NASA trial proves successful.

Soon laser trained engineers will be able real time data on any part of the earth to measure terrain mapping, measure how certain part of the earth is receiving rain or snow, be able to map moving storms and hurricane, measure athmospheric data and be able to record them; as the system improves it will be able to measure layers of the earth and surrounding wind, solar impact to the planet at any given time.

The space agency has rubber-stamped a trial of one of its projects - a laser-based communications system - which is theoretically capable of shifting up to 100Mb/s from spacecraft poking around the furthest corners of the solar system.

NASA's current space communications and data transfers are done on radio frequency (RF) systems.

The RF systems' data transmission rates mean that it takes 90 minutes for a single high-resolution image to be beamed back to Earth from Mars. The new laser-based system would allow 100Mbps data rates instead of 6Mbps, allowing a image to be transmitted in fast five minutes.

The trial run of the new optical laser system, dubbed the Laser Communications Relay Demonstration (LCRD), will require a "payload" of telescopes, lasers, mirrors, detectors, a pointing-and-tracking system, control electronics, and two different types of modems to be bolted onto a commercial communications satellite. NASA flying observatory planes could be used to measure athmospheric quality of air space and possibly garbages and flying litters around our planet.


The payload will include telescopes, lasers, mirrors, detectors, a pointing and tracking system, control electronics, and two different types of modems. One modem is ideal for communicating with deep space missions or tiny, low-power smallsats operating in low-Earth orbit. The other can handle much higher data rates, particularly from Earth-orbiting spacecraft, including the International Space Station. "With the higher-speed modem type, future systems could support data rates of tens of gigabits per second," Israel said.

Once the payload receives the data, it would then relay it back to ground stations now scheduled to operate in Hawaii and Southern California.

The multiple ground stations are important to demonstrating a fully operational system.
Cloud cover and turbulent atmospheric conditions impede laser communications, requiring a clear line of sight between the transmitter and receiver. If bad weather prevents a signal from being sent or received at one location, the network could hand over the responsibility to one of the other ground stations or store it for later retransmission.

The demonstration is expected to run two to three years.
The specially equipped stations on the ground will test the transmission by encoding digital data and transmitting the information to the payload, which will then be relayed back to ground stations located in Southern California and Hawaii (as illustrated below).
lcrd conceptual_illustration nasa
A conceptual illustration of the Laser 

One of the modems bundled into the the payload is ideal for communicating with deep space missions, while the other supports a much higher bit-rate and can communicate with Earth-orbiting craft, including the International Space Station.

During the demonstration – expected to run for two to three years – streams from the two modems will be sent back to Earth by laser to the Southern California and Hawaii ground stations – weather, atmospheric conditions and cloud cover permitting.If crappy weather stopped effective communication with one location, the network could hand over the responsibility to one of the other ground stations.

Image of solar sails.It's one of three projects that NASA decided to fund on 23 September. The other two are an atomic clock in deep space and a solar sail. This Solar Sail demonstration will enable propellantless in-space navigation for missions such as advanced geostorm warning, economic orbital debris removal, and deep space exploration.

›  Link to larger photo

Image of solar sails. 
The Solar Sail demonstration mission will deploy and operate a sail area 7 times larger than ever flown in space with potential applicability to a wide range of future space missions, including use in an advanced space weather warning system to provide more timely and accurate notice of solar flare activity. 

The National Oceanic and Atmospheric Administration (NOAA) is collaborating with NASA and L'Garde Inc. on the solar sail demonstration. Solar sails offer many potential game-changing mission capabilities including:
  • Orbital Debris: Orbital debris can be captured and removed from orbit over a period of years using the small solar-sail thrust.
  • De-orbit of spent satellites: Solar sails can be integrated into satellite payloads so that the satellite can be de-orbited at the end of its mission.
  • Station keeping: Using the low propellantless thrust of a solar sail to provide station keeping for unstable in-space locations.
    • As an example, the GeoStorm project considers locating solar storm warning satellites at pseudo Lagrange points three times further from the Earth by using the solar sail to cancel some solar gravitational pull, thus increasing warning time from ~15 minutes to ~45 minutes.
    • Providing a satellite with a persistent view of northern or southern latitudes, i.e., a “pole-sitter” project. This allows the observational advantages of today’s geosynchronous satellites for orbits with view angles of the northern and southern high-latitudes.
  • Deep space propulsion: Payloads free of the Earth’s pull can be continuously and efficiently accelerated to the other planets, or out of the solar system, such as proposed in Project Encounter.
The Solar Sail demonstration will:
  • Demonstrate the deployment of a 38m x 38m solar sail in space (quadrupling the area of the largest sail deployed and tested on the ground of 20m x 20m by L’Garde at NASA’s Plumbrook facility in Ohio).
  • Demonstrate attitude control plus passive stability and trim using beam-tip vanes.
  • Execute a navigation sequence with mission-capable accuracy.

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