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A single lander with an IPN gateway to a (real
or virtual) internal network |
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Small number of cooperating robots on planetary
surface (e.g. Single lander, single rover) |
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Orbiter-to-surface communication and
coordination (e.g. sample return recovery) |
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Multiple beyond-line-of-sight missions connected
by low-orbit communication satellites |
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Planet-stationary satellites for relay and
gateway functions |
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Spacecraft on-board LANs |
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The Earth’s Internet |
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Science Data and Telemetry Return |
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Command and Control of In-Situ Elements |
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Telescience/Virtual Presence |
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Initially back-hauled to earth |
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Secondarily, in support of robotic control of
robotic exploration |
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Eventually, in support of human in situ control
of robotic exploration |
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Power availability affects all aspects of
deployed internet operation |
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Solar conversion is the primary power source for
foreseeable future |
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Example:
The average solar intensity in Mars orbit is 590 W/m2, compared with
1370 W/m2 in Earth orbit |
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Surface-based solar panels are subject to |
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Atmospheric dust limiting available solar energy |
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Dust build-up on/erosion of solar panels,
reducing effectiveness over time |
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Location-based reductions in solar intensity |
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Seasonal variations in solar intensity |
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Efficiency of communication at all layers is
required to offset the limitations of power availability |
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A set of high-capacity, high-availability links
between network traffic hubs |
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Terrestrial backbone links are between hubs like
Houston and Chicago. |
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Interplanetary backbone links are between hubs
like Earth and Mars. |
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Cost per second of transmission is very high,
so… |
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Don’t waste transmission opportunities. |
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Intra-backbone connectivity might never be
end-to-end, so… |
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Don’t rely on end-to-end connectivity for
protocol operations. Use
store-and-forward techniques. |
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End-to-end round trip time may vary from minutes
to weeks, so… |
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Don’t rely on negotiation or other
conversational protocol mechanisms; by the time a conversation converges,
the reason for it may have passed.
Make protocol decisions autonomously, locally. |
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There is a working prototype: the CCSDS File
Delivery Protocol (CFDP). |
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Architecturally very similar to IPN. |
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International standard, four experimental
implementations. |
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Baselined for Deep Impact mission, potentially
others. |
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But CFDP was designed to support individual
space flight missions, not to serve as the infrastructure for a permanent,
general-purpose network. |
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Addressing scheme is simple but limited. |
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Application, transport, network, and reliable
link layers are combined into a single protocol, which only does file
transfer. |
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Specification of proposed IPN protocols is under
way. |
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Intermittent connectivity suggests an Email-like
architecture |
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Common “Handling Instructions” for a data
collection |
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Network must accommodate the persistence and
transfer of state |
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Names (not addresses) are the means of reference |
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Names have two parts: a routing part (specifies the IPN
region) and an administrative
part (specifies the DNS name) |
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Routing between IPN regions based upon routing
part of the name |
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Late-Binding |
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Separate addressing domains for each internet;
administrative names converted to local addresses only at the destination
IPN region |
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Indirection |
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Inherent dependence on intermediate relay agents |
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Custodial transfer |
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Intermediate nodes assume possibly-long-term
responsibility for data forwarding |
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“Bundles” as a common end-to-end transfer
mechanism |
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A region is an area where the relevant
characteristics of communication are homogeneous |
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One can define regions that are based upon: |
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Communications capability |
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Quality of Service Peerings |
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Security (levels of trust) |
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Degree of resource management |
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Etc. |
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Traversal of two or more regions will effect the
nature of communications |
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