---
title: "Criticism of the Space Shuttle program"
chunk: 3/4
source: "https://en.wikipedia.org/wiki/Criticism_of_the_Space_Shuttle_program"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:08:53.010543+00:00"
instance: "kb-cron"
---

As the Soviets demonstrated, capsules and uncrewed supply rockets are sufficient to supply a space station.
NASA's initial policy of using the Shuttle to launch all crewless payloads declined in practice, and eventually was discontinued. Expendable launch vehicles (ELVs) proved much cheaper and more flexible.
Following the Challenger disaster, use of the Shuttle to carry the powerful liquid fueled Centaur upper stages planned for interplanetary probes was ruled out for Shuttle safety reasons.
The Shuttle's history of unexpected delays also made it liable to miss narrow launch windows.
Advances in technology have made probes smaller and lighter. As a result, many robotic probes and communications satellites can now use expendable launch vehicles, such as the Delta and Atlas V, which are less expensive and perceived to be more reliable than the Shuttle.
Advances in technology today happen much faster than in the years the Shuttle was developed. Thus the notion that Shuttle would be useful for recovering expensive satellites for return to Earth for refurbishment and updating with new technology is obsoleted; costs have dropped and capabilities increased so much that it is much more cost-effective to abandon old satellites and simply launch new ones.

== Accidents ==

While the technical details of the Challenger and Columbia accidents are different, the organizational problems show similarities. Flight engineers' concerns about possible problems were not properly communicated to or understood by senior NASA managers. The vehicle gave ample warning beforehand of abnormal problems. A heavily layered, procedure-oriented bureaucratic structure inhibited necessary communication and action. In addition, both mission failures have been attributed to the flawed notion of a crewed orbiter attached to the flank of the launch vehicle, precluding the possibility of ejection in the case of the Challenger disaster, and exposing the heat shield to damage in the case of Columbia.
With Challenger, an O-ring which should not have eroded at all did erode on earlier shuttle launches. Yet managers felt that because it had previously eroded by no more than 30%, this was not a hazard as there was "a factor of three safety margin" (in reality, the part had failed, and there was no safety factor). Morton-Thiokol designed and manufactured the SRBs, and during a pre-launch conference call with NASA, Roger Boisjoly, the Thiokol engineer most experienced with the O-rings, pleaded with management repeatedly to cancel or reschedule the launch. He raised concerns that the unusually low temperatures would stiffen the O-rings, preventing a complete seal during flexing of the rocket motor segments, which was exactly what happened on the fatal flight. However, Thiokol's senior managers, under pressure from NASA management, overruled him and allowed the launch to proceed. One week prior to the launch, Thiokol's contract to reprocess the solid rocket boosters was also due for review, and cancelling the flight was an action that Thiokol management wanted to avoid. Challenger's O-rings eroded completely through as predicted, resulting in the complete destruction of the spacecraft and the death of all seven astronauts on board.

Columbia was destroyed because of damaged thermal protection from foam debris that broke off from the external tank during ascent. The foam had not been designed or expected to break off, but had been observed in the past to do so without incident. The original shuttle operational specification said the orbiter thermal protection tiles were not designed to withstand any debris hits at all. Over time NASA managers gradually accepted more tile damage, similar to how O-ring damage was accepted. The Columbia Accident Investigation Board called this tendency the "normalization of deviance" –  a gradual acceptance of events outside the design tolerances of the craft simply because they had not been catastrophic to date.

The subject of missing or damaged thermal tiles on the Shuttle fleet only became an issue following the loss of Columbia in 2003, as it broke up on re-entry. In fact, Shuttles had previously come back missing as many as 20 tiles without any problem. STS-1 and STS-41 had both flown with missing thermal tiles from the Orbital Maneuvering System pods (visible to the crew). The problem on Columbia was that the damage was sustained from a foam strike to the reinforced carbon-carbon leading edge panel of the wing, not the heat tiles. The first Shuttle mission, STS-1, had a protruding gap filler that diverted hot gas into the right wheel well on re-entry, resulting in a buckling of the right main landing gear door.

=== Risk contributors ===
An example of technical risk analysis for an STS mission is SPRA iteration 3.1 top risk contributors for STS-133:
Micro-Meteoroid Orbital Debris (MMOD) strikes
RS-25-induced or RS-25 catastrophic failure (the Space Shuttle Main Engine)
Ascent debris strikes to TPS leading to LOCV on orbit or entry
Crew error during entry
RSRM-induced RSRM catastrophic failure (RSRM are the rocket motors of the SRBs)
COPV failure (COPV are tanks inside the orbiter that hold gas at high pressure)