The Indian Space Research Organisation (ISRO) is preparing for an important occasion — the 50th flight of the Polar Satellite Launch Vehicle (PSLV), popularly dubbed the the space agency’s “'trusted workhorse.”

The PSLV-C48 mission scheduled for a December 11 lift-off will be the 50th of the launch vehicle that has played an important role in earning ISRO the respect of bigger space-faring cousins.

To date, 49 PSLV missions have lifted off from the Satish Dhawan Space Centre, Sriharikota. They include the initial three developmental flights — designated PSLV D-1, D2 and D3 — and 46 operational flights. The total score counts in two failed missions and the PSLV variants such as PSLV-XL and PSLV-CA, officials of Vikram Sarabhai Space Centre (VSSC), ISRO’s lead agency for launch vehicles, said.

By all rights, the PSLV-C47 mission that flew on November 27 this year should have been logged as the 50th flight. Had ISRO stuck to the natural progression of numbers, that is. After the PSLV-C12 flight on April 20, 2009, the space agency nimbly leap-frogged to the C14 mission. ISRO lore goes that the number 13 was bypassed allegedly due to its association with ill-luck!

Along with heftier sibling Geosynchronous Satellite Launch Vehicle (GSLV), the PSLV continues to remain the mainstay of the Indian space program.

In a ‘career’ spanning nearly three decades, the PSLV has launched more than 40 Indian payloads — including the Chandrayaan 1 and Mars Orbiter Mission (Mangalyaan) spacecrafts — and 310 foreign satellites. The C37 mission has the credit of placing a whopping 104 satellites in orbit, a record.

The 50th flight would have on board 10 satellites, including India’s RISAT-2BR1 and nine small satellites from abroad, VSSC officials said.

Successor to the SLV and ASLV, PSLV is ISRO’s third-gen launch vehicle, capable of placing payloads in different orbits including the Geosynchronous Transfer Orbit (GTO). Sporting four stages, its standard version is equipped with two liquid and two solid stages plus six strap-on boosters. The core-alone version, PSLV-CA, flies without the boosters.

The first developmental flight of the PSLV lifted off 26 years ago, on September 20, 1993. Designated the PSLV-D1, it was unsuccessful in its mission, failing to place the IRS-1E satellite in orbit. The second and third missions were successes. The first operational flight - PSLV-C1 on September 29, 1997, was a partial disappointment as the fourth stage under-performed.

After that, the PSLV notched up a long string of successes, becoming, in the process, ISRO’s pride and joy. The only big disappointment since then came in August 2017, when the heat shield on the PSLV C-39 mission bearing an Indian Regional Navigational Satellite System (IRNSS) satellite failed to separate, trapping the payload inside.

Most of the top names in ISRO have at one time or the other associated with the PSLV project in their career. The first project director was Dr. S. Srinivasan, a pioneer of the Indian space program.