Source: IE
Context:
The Indian Space Research Organisation (ISRO) recently reported the failure of an atomic clock onboard the navigation satellite IRNSS-1F, which is part of India’s regional navigation system NavIC (Navigation with Indian Constellation). The failure reduces the number of fully functional satellites in the constellation.
What is an Atomic Clock?
An atomic clock is an extremely precise timekeeping device that measures time based on the vibrations of atoms, typically Rubidium or Cesium.
Importance in Navigation Satellites
- Navigation systems depend on extremely accurate timing signals.
- Even a billionth of a second error can cause a location error of several meters on Earth.
- Atomic clocks ensure that satellite signals carry accurate timestamps, which are essential for calculating precise positions.
How Atomic Clocks Work
Atomic Resonance
- The clock measures the precise frequency of electromagnetic radiation emitted or absorbed when electrons change energy levels in an atom.
Ultra-Stable Frequency
- Atoms vibrate at a constant frequency, unlike quartz or mechanical clocks that can drift over time.
Time-of-Flight Measurement
- The satellite transmits a signal with a timestamp indicating when it was sent.
Trilateration
- A receiver calculates the distance from multiple satellites by comparing the sent and received time.
- Signals from at least four satellites are used to determine latitude, longitude, and altitude.
About NavIC (Navigation with Indian Constellation)
- NavIC is India’s independent regional satellite navigation system, earlier known as the Indian Regional Navigation Satellite System (IRNSS).
Launch Timeline
- The first satellite, IRNSS-1A, was launched in July 2013.
- The original constellation aimed to deploy seven satellites by 2016, with additional replacement satellites launched later.
Coverage Area
- Provides navigation services across India and about 1,500 km beyond its borders.
