the life of the Shuttle program. A 2017 study found that carrying one kilogram of cargo to the ISS on the Shuttle cost $272,000 in 2017 dollars, twice the cost of Cygnus and three times that of Dragon. NASA used a management philosophy known as success-oriented management during the Space Shuttle program which was described by historian Alex Roland in the aftermath of the Columbia disaster as "hoping for the best". Success-oriented management has since been studied by several analysts in the area. Accidents In the course of 135 missions flown, two orbiters were destroyed, with loss of crew totalling 14 astronauts: Challenger – lost 73 seconds after liftoff, STS-51-L, January 28, 1986 Columbia – lost approximately 16 minutes before its expected landing, STS-107, February 1, 2003 There was also one abort-to-orbit and some fatal accidents on the ground during launch preparations. STS-51-L (Challenger, 1986) Close-up video footage of Challenger during its final launch on January 28, 1986 clearly shows that the problems began due to an O-ring failure on the right solid rocket booster (SRB). The hot plume of gas leaking from the failed joint caused the collapse of the external tank, which then resulted in the orbiter's disintegration due to high aerodynamic stress. The accident resulted in the loss of all seven astronauts on board. Endeavour (OV-105) was built to replace Challenger (using structural spare parts originally intended for the other orbiters) and delivered in May 1991; it was first launched a year later. After the loss of Challenger, NASA grounded the Space Shuttle program for over two years, making numerous safety changes recommended by the Rogers Commission Report, which included a redesign of the SRB joint that failed in the Challenger accident. Other safety changes included a new escape system for use when the orbiter was in controlled flight, improved landing gear tires and brakes, and the reintroduction of pressure suits for Shuttle astronauts (these had been discontinued after STS-4; astronauts wore only coveralls and oxygen helmets from that point on until the Challenger accident). The Shuttle program continued in September 1988 with the launch of Discovery on STS-26. The accidents did not just affect the technical design of the orbiter, but also NASA. Quoting some recommendations made by the post-Challenger Rogers commission: STS-107 (Columbia, 2003) The Shuttle program operated accident-free for seventeen years and 88 missions after the Challenger disaster, until Columbia broke up on reentry,