There were two Polar Satellite Launch Vehicle (PSLV) failures during the 1990s. The first failure occurred on September 20, 1993, during the launch of IRS-1E. The second failure occurred on September 4, 1997, during the launch of IRS-1D.

The PSLV is a four-stage expendable launch vehicle developed by the Indian Space Research Organisation (ISRO). It is designed to launch satellites into low Earth orbit (LEO), Sun-synchronous orbit (SSO), and geosynchronous transfer orbit (GTO).

The first PSLV failure occurred during the launch of IRS-1E on September 20, 1993. The launch vehicle failed to ignite after the second stage separated. The IRS-1E satellite was destroyed.

The second PSLV failure occurred during the launch of IRS-1D on September 4, 1997. The launch vehicle failed to achieve orbit due to a problem with the third stage. The IRS-1D satellite was also destroyed.

The PSLV failures in the 1990s were setbacks for ISRO, but they also helped the organization to learn from its mistakes and improve the reliability of the launch vehicle. Since the 1990s, the PSLV has had a very high success rate, with only two failures in over 50 launches.

The PSLV is now one of the most reliable launch vehicles in the world. It is used to launch a variety of satellites for both commercial and government customers. The PSLV has helped to make India a major player in the global space launch market.

Here are some of the reasons for the PSLV failures in the 1990s:

• Inexperience: ISRO was relatively new to the launch vehicle business in the 1990s. The PSLV was the first indigenously developed launch vehicle in India, and ISRO was still learning how to operate it safely.
• Technical problems: There were also some technical problems with the PSLV in the 1990s. These problems were eventually fixed, but they contributed to the two failures that occurred during this period.

Despite the failures, the PSLV has been a very successful launch vehicle. It has helped to make India a major player in the global space launch market, and it is now one of the most reliable launch vehicles in the world.