Communications Strategies, How can the Deep-Space Network be improved on? |
Communications Strategies, How can the Deep-Space Network be improved on? |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 1018 Joined: 29-November 05 From: Seattle, WA, USA Member No.: 590 ![]() |
Given the recent news that Cassini will lose some data during the Phoenix landing due to contention for DNS access:
http://www.unmannedspaceflight.com/index.p...ic=4831&hl= It seemed reasonable to create a topic to discuss where the DNS might be going. Jasedm suggested a relay station at the Earth-Sun L2 point, which I think might be discussing (despite the expense) assuming the relay station could use laser communication with space probes, while beaming data to Earth via microwaves. I know that experiments with laser communications were part of the now-abandoned Mars Telecommunications Orbiter, and I know that there was even a recent laser experiment involving Mercury Messenger. http://www.space.com/missionlaunches/060104_laser_comm.html These seem intended to support laser communications with ground-based receivers, though -- something that seems much too risky if remote space probes can't store days of data allowing for multiple retries. Obviously a relay station would have its own risks -- you'd probably need two for redundancy -- and it'd be fabulously expensive, but it might also include quite a few savings as well. I've looked for figures for what the DSN costs to run, but I haven't found them yet. Not sure how large a part of a given mission (if any) is charged to the DSN, but it seems to me that a relay satellite ought to be a good bit cheaper to operate, and for far higher bandwidth. Also, a laser transmitter ought to be lighter and consume less power than an equivalent microwave transmitter. That alone could result in huge savings for outer-system missions. The only time I saw a serious proposal for a laser-to-satellite communications system was in a description of options for the "Grand Tour" that later became Voyager. (Assuming that counts as serious.) :-) With DSN needing more and more maintenance, I wonder if anyone is seriously considering laser for the future. --Greg |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 ![]() |
"...In my experience, we don't need new sites in different locations..."
Actually, we do. We nees 6 DSN sites... North and south pairs. 120 degrees around the globe, roughly. There was an original S. African DSN site that was closed due to the anti-aparthide embargo, resulting in the building of the one in Spain. We've lost high-value encounter data at times due to the lack of a north-south redundant DSN pair during hardware failures or severe rain events, etc. Also, spacecraft at far south or north limits of the ecliptic <or beyond> can be harder to track from the opposite hemisphere. |
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