On Thursday, the Indian space agency, ISRO, suffered a rare failure when its Polar Satellite Launch Vehicle failed to launch a navigation satellite into its proper orbit. It was the first failure of the workhorse launch vehicle, which is capable of lifting about four tons to low Earth orbit, in two decades.

So far, the Indian space agency has yet to say too much about the cause of the failure. Officials have confirmed that the payload fairing did not detach properly from the rocket after launch. This is the protective shroud around the satellite that protects it during the ride through the atmosphere. During brief moments of the webcast, the satellite could be seen trying to separate inside the fairing.

The Polar Satellite Launch Vehicle flies about half a dozen times a year, and in recent years, operators of small satellites have booked flights on the Indian rocket due to its lower cost (approximately $15 million) and reliability. Earlier this year, for example, the Indian rocket launched dozens of small commercial satellites at the same time. The payload lost Thursday was the Indian Regional Navigation Satellite System 1H satellite.

This is the fifth orbital rocket failure of 2017 according to data kept by Space Launch Report. Whereas the traditional rocket powerhouses of Russia, the United States and Europe have enjoyed success, some of the relative newcomers have faltered. Of this year's 54 orbital launch attempts, the five failures have been the Indian rocket, a Chinese Long March 5 rocket, a Chinese CZ-3B rocket, Rocket Lab's first attempt of its Electron launch vehicle, and an experimental Japanese orbital rocket, the SS-520-4.

Given that four months remain in 2017, this could be a relatively bad year for orbital rocket success, although some of this may be attributable to the experimentation of Rocket Lab and others. During this decade, about one in 20 orbital launches have failed, with an average of 4.4 launch failures per year. The last time six or more rockets failed in a given year was 2011.

As ever, space remains hard.