Re-Entry: Iridium 77

Image: Iridium Communications
Photo: Smithsonian Air & Space Museum

Iridium 77 re-entered the atmosphere on September 22, 2017 after over 19 years in orbit as part of the original Iridium Communications Constellation, a low-orbiting satellite system for global communications including voice and point-to-point data services via 66 active satellites in six orbital planes. The original constellation satellites – 95 of which launched between 1997 and 2002 – were build by Motorola and Lockheed Martin based on the LM-700 satellite platform, communicating with ground terminals in L-Band and using space-to-space Ka-Band links for inter-satellite communications to route packets to their destination.

In 2017, Iridium Communications began deployment of the Iridium-NEXT constellation, marking the largest constellation upgrade in history as all heritage Iridium craft are to be replaced with NEXT satellites in less than two years. Launching on Falcon 9 rockets ten at a time, the Thales and Orbital ATK-built Iridium-NEXT satellites feature much-improved communications terminals supporting higher data speeds while the overall constellation retains its architecture with 66 active spacecraft plus nine orbital spares to guarantee true global coverage.

As new satellites enter the constellation, Iridium is using remaining fuel on the old constellation craft to de-boost their orbits, lowering their perigee to a minimal altitude to speed up their orbital decay.

>>Iridium-NEXT Satellite & Constellation Overview

NORAD ID: 25471
Origin: U.S.
Object: Iridium-77
Type: Low Earth Orbit Communications Satellite
Launch Mass: 689 Kilograms

Launched: September 8, 1998 – 21:13 UTC
Launch Vehicle: Delta II 7920-10C
Launch Site: SLC-2W, Vandenberg Air Force Base
Operational Orbit: 780 x 780 km, 86.4°
Deboost Completion: August 23, 2017

Re-Entry Prediction: September 22, 2017 – 01:39 UTC +/-29 Minutes
Re-Entry Zone: Unknown

Re-Entry Orbit
Image: Spaceflight101/Orbitron