As ISRO launch fails, glitch in space waits for fix: 

As ISRO launch fails, glitch in space waits for fix: 

Context

• ISRO declared the IRNSS-1H launch a failure after a heat shield failed to separate, preventing the satellite from being deployed in space by PSLV-C39, the launch vehicle.

What went wrong?

• The performance of PSLV-C39 went to plan up to the point when the satellite had to be inserted in orbit.
• During the operation the heat shield did not get separated.

IRNSS-1H

• IRNSS-1H was the eighth in a series of IRNSS (Indian Regional Navigation Satellite Systems) satellites to get launched by ISRO since July 2013.
• IRNSS-1H was among nine satellites (seven for the navigation service, two backup) indented at Rs 1,420 crore for IRNSS.

NavIC

• It is an Indian navigation satellite constellation, comprising of seven satellites.

What was IRNSS-1H supposed to do?

• It was launched to create a constellation to provide satellite-based navigation services over the Indian subcontinent on the lines of the global positioning system (GPS) created by the United States.
• IRNSS-1H was intended to replace IRNSS-1A, which developed problems last year.
• IRNSS-1H would have augmented “the existing seven satellites of NavIC constellation”.
• It was supposed to sit in a sub-Geosynchronous Transfer Orbit (sub-GTO).

What kind of problems made a replacement necessary?

• The first satellite launched on July 1, 2013, had developed problems, rendering the satellite ineffective for navigation services.
• The Three Rubidium Atomic Frequency Standard (RAFS) clocks of IRNSS-1A have stopped working. But the rest of satellite components are functioning perfectly.
• The satellite is still being used for messaging activity.
• There is a talk of launching a replacement site.

After the failed launch, what can ISRO do?

• ISRO has one more satellite in its kitty. A new satellite could be launched in the next few months to make up for the loss.

How do these satellites work?

• IRNSS intends to provide two services —

Standard Positioning Service for general users and a Restricted Service, which is an encrypted service only for authorized users like the defence forces.

NavIC is designed to provide accurate position information services to users in India as well as the region, up to 1,500 km from the boundary.

For NavIC to become ubiquitous in the subcontinent, ISRO will sell its capabilities to general positioning service providers like mobile phone manufacturers, vehicle manufacturers etc.

Couldn’t existing satellite systems have provided such services?

• One primary reasons for the development of the indigenous Indian system is the reliability that it offers when used for defence purposes.

What is the payload on IRNSS-1H?

• IRNSS-1H had both a navigation payload and a ranging payload.
• The ranging payload of IRNSS satellites has a C-band transponder to determine the range of the satellite.
• The navigation payload is meant to transmit navigation service signals to users on earth while operating in the L5-band and S-band. Part of the navigation payload is high-accuracy RAFS clocks.

Importance of the clocks

• Atomic clocks act as a key component in a navigation system.
• The ISRO satellites are equipped with three clocks each – one clock being the primary timekeeper and two acting as backup.
• Accurate timekeeping is important for navigation system as a person’s position on earth is subject to the accurate calculation of delays in signal transmission from the satellite to earth.
• Clocks are so important because if you don’t have the right clocks and even if you don’t consider the relativity theory of Einstein the error would be more than 500 metres in one hour.

What went wrong with the clocks?

• The Three RAFS clocks supplied by an European manufacturer, Spectratime, which were used by the ESA for its Galileo satellite navigation system, developed problems.
• These failures seem to have a consistent signature, linked to probable short circuits, and possibly a particular test procedure performed on the ground.

How has ISRO addressed the problems with the IRNSS clocks?

• The atomic clocks in new satellites are modified versions of the original clocks provided by Spectratime under a 4-million-euro deal signed in 2008.
• ISRO has been carrying out modifications of clocks acquired from Spectratime to overcome technical issues.

Who built IRNSS-1H?

• A consortium led by Alpha Design Technologies, a defence equipment supplier from Bengaluru, built it over eight months.
• The Rs 400-crore company was tasked with making two satellites.
• The second is expected to be complete by April 2018.
• Alpha Designs was backed by a team of 70 ISRO scientists.