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Is a Laser Data Link 1.5 Million Kilometers Feasible?
An anonymous reader writes "On the Canary Islands last week, a team from Oerlikon Space demonstrated the feasibility of a laser link across a distance of 1.5 million kilometers for the first time ever. In the future, laser links like this one will be able to transmit data across huge distances through the universe far more rapidly and efficiently than is possible using conventional radio links today."
Correction:
Voyager is 15 billion kilometres not miles as stated (about 9 billion miles)
http://voyager.jpl.nasa.gov/mission/weekly-reports/index.htm
liqbase
Yes they do, since that focus is never perfect. A cheapie laser pointer will show a 1/8" dot at 30 feet and a 1/4" smudge at 60 feet.
A house divided against itself cannot stand.
Wrong, they do follow the inverse square law.
See the article you link to, which states that perfect collimation can never be achieved in reality. Thus, like any other source, laser light follows the inverse square law in the far field.
Note that in general, I believe the inverse square law only applies to a point source, or a source which is effectively a point source at the distances involved. For dealing with cases where the source can't be approximated as a point (either because it's really large, or the radiation intensity is being measured very close to the source), RF engineers use the term "near field gain reduction" for the behavior of RF field intensities in close proximity to an antenna, which probably has an equivalent term for optics. As a result, for an optical source with a large aperture in relatively close physical proximity to the aperture, the inverse square law will appear not to apply, but once the "near field" for that source is exited, the inverse square law holds.
retrorocket.o not found, launch anyway?
The basic problem is that the LaGrange points 4-5 are stable, but require a fair bit of energy to get to in part because you have to slow down a lot more (no nice large gravity well to assume an orbit around).
In general the amount of time to get there/back would be dependant on how much energy you want to put into getting there and back.
Finally we do already have a satellite (SOHO) on the L1 point relative to Earth and the Sun. This is an unstable point so some energy is used maintaining position However it is a telescope on an L point relative to the Earth and Sun.
LedgerSMB: Open source Accounting/ERP
"Uplink communications is via S-band (16-bits/sec command rate) while an X-band transmitter provides downlink telemetry at 160 bits/sec normally and 1.4 kbps for playback of high-rate plasma wave data. All data are transmitted from and received at the spacecraft via the 3.7 meter high-gain antenna (HGA)."
The laser that my wife blasts the moon with on a regular basis starts at 3.5 meters here and I've heard is over 2km when it hits the moon. I have no idea how big it is when it finally bounces back.
When you sympathize with stupidity, you start thinking like an idiot.