The Indian Space Research Organisation (ISRO) has revealed the cause of the recent launch failure of its PSLV launch vehicle. That flight (PSLV C39) in August 2017 failed to deliver the IRNSS-1H navigation satellite payload, which remains aboard the rocket. The payload is thought to have separated from its rocket adaptor but remained encapsulated because the clamshell fairing stayed in place.
Diagram of IRNSS 1H inside the PSLV fairing. Courtesy: ISRO via Jonathan McDowell
The cause was that a fairing separation system did not work due to pyro-charge underperformance. A rubber bellow between the two vertical halves of the heat shield was supposed to expand, with the gas pressure generated by ignition of the pyro devices. The explosion should have detached the two parts of the heat shield. However, the pressure generated was not enough for the bellow to expand and trigger separation. The failure investigation conclusions were revealed by PSLV project director R Hutton in the Economic Times of India.
The encapsulated spacecraft is in a 5,308 x 157 km orbit at an inclination of 19.16 degrees. The low perigee of this orbit means that it is likely to re-enter within the next few weeks. The protective nature of the fairing (it is designed to provide a measure of aero-thermodynamic protection during launch) could allow the 1.5 metric ton spacecraft – along with its poisonous and carcinogenic hydrazine propellant – to survive re-entry. If it does, it will have an approximate 30 per cent chance of hitting land within plus or minus 19 degrees of the equator.
In a separate development, the original small Chinese space station with a mass of 8.5 metric tons, Tiangong-1, is also due to re-enter the Earth’s atmosphere in an uncontrolled manner within the next few months. Parts of the station are expected to survive re-entry and strike the Earth on land or sea between plus or minus 42 degrees from the equator.
…As ISRO gets a new director
Dr K Sivan took over the role of chairman of ISRO on 12 January 2018. Dr Sivan was previously director of the Vikram Sarabhai Space Centre (VSSC).
