Editing Interplanetary Internet (section)

== Challenges and reasons ==

In the core implementation of Interplanetary Internet,  satellites orbiting a planet communicate to other planet's satellites. Simultaneously, these planets revolve around the Sun with long distances, and thus many challenges face the communications. The reasons and the resultant challenges are:<ref>{{Cite journal|last1=Yang|first1=G.|last2=Wang|first2=R.|last3=Zhao|first3=K.|last4=Zhang|first4=X.|last5=Li|first5=W.|last6=He|first6=X.|date=2018-12-01|title=Queueing analysis of DTN protocols in deep-space communications|url=https://ieeexplore.ieee.org/document/8650570|journal=IEEE Aerospace and Electronic Systems Magazine|volume=33|issue=12|pages=40–48|doi=10.1109/MAES.2018.180069|s2cid=67876545|issn=1557-959X|access-date=February 1, 2021|archive-date=December 7, 2021|archive-url=https://web.archive.org/web/20211207044648/https://ieeexplore.ieee.org/document/8650570|url-status=live|url-access=subscription}}</ref><ref>{{Cite journal|last1=Alhilal|first1=A.|last2=Braud|first2=T.|last3=Hui|first3=P.|date=2019-08-14|title=The Sky is NOT the Limit Anymore: Future Architecture of the Interplanetary Internet|url=https://ieeexplore.ieee.org/document/8799061|journal=IEEE Aerospace and Electronic Systems Magazine|volume=34|issue=8|pages=22–32|doi=10.1109/MAES.2019.2927897|s2cid=54217081|issn=1557-959X|access-date=October 24, 2020|archive-date=October 24, 2020|archive-url=https://web.archive.org/web/20201024011331/https://ieeexplore.ieee.org/document/8799061|url-status=live}}</ref>

# The motion and long distances between planets:  The interplanetary communication is greatly delayed due to the interplanetary distances and the motion of the planets. The delay is variable and long, ranging from a couple of minutes (Earth-to-Mars), to a couple of hours (Pluto-to-Earth), depending on their relative positions. The interplanetary communication also suspends due to the solar conjunction, when the sun's radiation hinders the direct communication between the planets. As such, the communication characterizes lossy links and intermittent link connectivity.
# Low embeddable payload: Satellites can only carry a small payload, which poses challenges to the power, mass, size, and cost for communication hardware design. An asymmetric bandwidth would be the result of this limitation.<ref>{{Cite journal|last1=Zhao|first1=K.|last2=Wang|first2=R.|last3=Burleigh|first3=S. C.|last4=Sabbagh|first4=A.|last5=Wu|first5=W.|last6=Sanctis|first6=M. De|date=2016-10-01|title=Performance of bundle protocol for deep-space communications|url=https://ieeexplore.ieee.org/document/7812881|journal=IEEE Transactions on Aerospace and Electronic Systems|volume=52|issue=5|pages=2347–2361|doi=10.1109/TAES.2016.150462|bibcode=2016ITAES..52.2347Z|s2cid=25304383|issn=1557-9603|access-date=February 1, 2021|archive-date=December 7, 2021|archive-url=https://web.archive.org/web/20211207044651/https://ieeexplore.ieee.org/document/7812881/|url-status=live|url-access=subscription}}</ref>  This asymmetry reaches ratios up to 1000:1 as downlink:uplink bandwidth portion.
# Absence of fixed infrastructure: The graph of participating nodes in a specific planet-to-planet communication keeps changing over time, due to the constant motion. The routes of the planet-to-planet communication are planned and scheduled rather than being opportunistic.

The Interplanetary Internet design must address these challenges to operate successfully and achieve good communication with other planets. It also must use the few available resources efficiently in the system.