Correct Answer: b) Direct data transfer between satellites
Intersatellite links (ISLs) enable direct communication between satellites without needing to route data through ground stations, improving network efficiency and reducing latency.
Correct Answer: c) Ka and V bands
Ka-band (26.5-40 GHz) and V-band (40-75 GHz) are commonly used for RF intersatellite links because they offer wide bandwidths for high data rates while having manageable atmospheric effects in space.
Correct Answer: b) Higher data rates
Laser intersatellite links can achieve much higher data rates (often multiple Gbps) compared to RF links due to their higher carrier frequencies and narrower beamwidths.
Correct Answer: b) Iridium
The Iridium satellite constellation, launched in the late 1990s, was one of the first to implement operational intersatellite links using Ka-band crosslinks between satellites.
Correct Answer: b) Precise pointing and tracking
Laser beams are extremely narrow, requiring highly accurate pointing (typically within microradians) and tracking systems to establish and maintain links between moving satellites.
Correct Answer: d) Both a and b
Intersatellite links reduce latency by enabling direct satellite-to-satellite communication paths and reducing dependence on ground stations, which often require multiple hops.
Correct Answer: c) Mesh topology
Intersatellite links typically create a mesh network where each satellite can communicate with multiple neighbors, providing multiple paths for data and increasing network resilience.
Correct Answer: b) ESA
The European Space Agency (ESA) is developing the European Data Relay System (EDRS) which uses laser communication technology for high-speed data transfer between satellites.
Correct Answer: c) Susceptibility to interference
RF intersatellite links are more susceptible to interference and require frequency coordination, while laser links have narrower beams that are harder to intercept and interfere with.
Correct Answer: b) Via cross-plane links at orbital intersections
In LEO constellations, satellites in different orbital planes can establish temporary crosslinks when their orbits intersect, allowing data to flow between different planes of the constellation.