Simulation of IRNSS Navigation Payload Operations for End to End Payload Testing

Fault free operations of space vehicles have always been a challenging task. Every space mission requires stringent qualification process on ground for qualification of the space vehicle for mission operations. This paper deals with the simulation of IRNSS navigation payload operations on ground for end to end payload testing and qualification of the payload for broadcast of IRNSS navigation parameters. IRNSS is an emerging Indian regional navigation satellite system for providing the satellite based navigation service over India and neighboring region. The system is optimally designed for its space and ground segment to provide the best in class navigation service. The space segment comprises of 7 satellites with 4 satellites in geo-synchronous orbit and 3 in geo-stationary orbit. The navigation payload on-board every IRNSS spacecraft comprises of navigation signal generation unit, atomic clocks and ranging subsystems. For every IRNSS spacecraft, a series of tests are carried out during different phases of spacecraft integration and testing. The core elements of IRNSS navigation operations such as IRNSS navigation software, payload test receiver, atomic clocks and telecommand and telemetry subsystem all participate in simulation and end to end testing of navigation payload. This paper describes in detail the simulation of various mission scenarios with respect to navigation payload operations considering different phases of satellite operations, subsystems involved and environment. The simulation has been key to successful operations of IRNSS 1A and IRNSS 1B which are operational in IRNSS space segment. Keywords: IRNSS, Navigation, payload, simulatio

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead