From the brochure of the "Space and Science in Israel 2006" conference held on the third anniversary of the Columbia disaster
Tal Inbar, Senior Researcher, Fisher Institute for Strategic Air and Space Research
The Space Shuttle Discovery mission, known as STS-114, was the first space shuttle mission since the Space Shuttle Columbia disaster (STS-107) on February 2003, XNUMX. The Discovery mission was initially defined as an experimental mission. A task designed to provide information on various problems in the spacecraft's thermal insulation system, to examine the improvements in the photographic tracking system for the space shuttle (from the ground, from the air and from space), to examine in space conditions various repair procedures for the insulation sheath and to transfer equipment and supplies to the International Space Station.
In this article, I will review the causes of the malfunction in the space shuttle Columbia that resulted in its crash and the loss of its crew, the process of testing and investigation that was carried out and the first lessons from the STS-114 mission, while examining the technical/engineering aspects of the operation, the implications of its results for the future of the space shuttle program and the International Space Station, and for NASA. A. All of it.
What is the space shuttle?
The space shuttle is a reusable spacecraft, developed in the USA starting in 1972, and first flew into space in 1981. Each shuttle was designed for 100 flights. The ferry consists of three main parts:
• A spaceship with wings that enable soaring in the process of returning to Earth (Orbiter)
• A huge fuel tank containing liquid hydrogen and oxygen (ET - External Tank)
• Two boosters operating on solid fuel. (SRB – Solid Rocket Booster)
All the components of the space shuttle need to work in perfect coordination, in order to achieve success in the mission. The space shuttle can reach a low orbit around the Earth, launch satellites, return satellites from space to Earth, repair satellites and various systems in space, and dock at the International Space Station, which depends on the shuttle for the purpose of raising the various assemblies, transferring equipment, supplies and crews.
During the launch, three engines powered by hydrogen and liquid oxygen operate and in addition two auxiliary boosters containing solid fuel are ignited. About two minutes after takeoff, vessels that accelerate the fuel and they fall into the ocean, are collected and returned to use after a comprehensive overhaul. The space shuttle continues with the power of its engines to climb into space and after about six more minutes of flight, the fuel tank is also discarded, which burns up in the atmosphere and its fragments fall into the sea. The fuel tank is the only part of the ferry that cannot be reused.
An average space shuttle mission lasts about two weeks, during which it orbits the Earth at low altitude independently or is docked at the International Space Station. At the end of its mission, the shuttle activates small engines that slow down its speed and cause it to lose altitude. As its flight height decreases and it enters the atmosphere, the temperature of the air around the shuttle rises and reaches a peak of about 1,800 degrees Celsius.
At this stage, the shuttle operates as a giant lander, without a self-propelled mechanism, whose pilots direct it to the landing strip located at Kennedy Space Base or Edwards Air Force Base. After the shuttle lands, a long and complex phase of returning it to service begins, lasting from six months to a year and even more.
STS-107 mission
The space shuttle Columbia was the first shuttle to be launched into space (April 1981). Since this shuttle was limited to carrying relatively light cargo, and did not participate in the assembly mission of the International Space Station, it was chosen to carry out a scientific mission, which included conducting experiments in a variety of different scientific fields. Including two experiments that were carried out on an Israeli initiative: the MEIDEX experiment (Mediterranean Israeli Dust Experiment) in which observations were made of the dust in the Middle East atmosphere and the "Chemical Garden" experiment, in the preparation of which middle school students from the Ort Kiryat Motzkin school participated, which was designed to examine the development of crystals under conditions of lack -Weight.
On January 16, 2003, she launched Columbia for the STS-107 science mission, which lasted 16 days. The shuttle crew of seven astronauts also included Col. Ilan Ramon, a fighter pilot in the Air Force and the first astronaut of the State of Israel.
Once the scientific experiments were completed, the shuttle began the process of entering the atmosphere in order to land at the Kennedy Space Center in Florida. But at this stage something went wrong: during the entry into the atmosphere enormous forces are exerted on the shuttles and it is exposed to very high temperatures as a result of the entry into more and more compressed layers of air at high speed. The shuttle's heat protection system is designed to protect the shuttle from the enormous heat generated at this stage. However, when Columbia entered the atmosphere, something went wrong: initially, unusual indications were received from sensors located on the left wing of the shuttle, within a short time contact with the shuttle was lost, and then reports began to be received from eyewitnesses claiming to have observed what appeared to be fragments disintegrating and moving away from the shuttle during its entry into the atmosphere. The terrible truth soon became clear: while passing over Texas at a height of about 70 km and at a speed of about 20 thousand km/h, the Columbia disintegrated and its remains were scattered over a large area of several states in the USA. Seven STS-107 crew members perished in the disaster.
Columbia Accident Investigation Board (CAIB)
Following the disaster, an investigative committee was established at NASA whose task was to find out the reason for the loss of the shuttle. The committee issued a conclusive report, and found the technical cause that led to the Columbia disaster: a piece of insulation foam that fell from the external fuel tank 81 seconds after launch, hit the front part of the left wing and created a hole or cracks, which allowed the hot air to penetrate into the shuttle and cause its loss.
Along with the direct technical cause of the accident, the investigative committee found a series of failures in the American space agency, including: poor organizational culture, failures in reporting between the various ranks, and more. The committee gave NASA's organizational culture equal weight to that of the technical malfunction in analyzing the causes of the shuttle disaster.
The main recommendations of the committee
The committee's recommendations were divided into three main categories. Return to flight: recommendations that, if not fulfilled, it will not be possible to renew the flights of the space shuttle fleet. No return to the flight: recommendations to be made, however, the flights can be renewed even before they are implemented. The future of the ferry: long-term recommendations, which must be filled in order to continue using the ferries until 2010.
Among the necessary recommendations for resuming flights:
• Preventing insulation foam from falling out of the fuel tank.
• Measuring and determining the structural strength of carbon-carbon components in the shuttle.
• Improving the shuttle's resistance to external impacts.
• Increasing the shuttle's ability to return safely to Earth even if it is slightly damaged.
• Improving the maintenance of the launch pad and its related systems.
• Considerable improvement in the photography system in order to provide at least three photography angles to assess the shuttle's condition from the moment of launch until the separation of the solid boosters.
• Installation of a high resolution image transmission system in real time from space to the ground.
• Development and maintenance of assessment capabilities based on tests and scientific models to examine possible damage to the space shuttle.
• Improving the anchoring points of the space shuttle to the fuel tank.
• Development of a highly advanced system for assessing damage in space and installing it on the mechanical arm of the space shuttle.
• Determining a realistic schedule for space shuttle flights.
• Implementation of a new training program for the team of astronauts, the control center and the launch pad personnel - to handle emergencies.
• Establishing work procedures between NASA and the American intelligence agencies in order to obtain satellite photographs of the space shuttle during its missions.
• Reorganization of the Space Shuttle Integration Office.
• Establishment of an independent safety team at the level of the subsystems and systems of the space shuttle.
• Building a database that will allow future improvement and upgrading of the space shuttle.
NASA's preparation for implementing the recommendations
The American space agency quickly prepared to implement the recommendations and estimated that within a year and a half since the Columbia disaster, it would be possible to resume space shuttle launches. In practice, the investigation committee's close monitoring of the implementation of the recommendations and other technical delays extended the time of organization to two and a half years. A noteworthy problem was an incorrect reading of the fuel sensor in the main fuel tank, which resulted in the cancellation of the Discovery launch less than an hour before the scheduled takeoff time. The sensor problem was not resolved and the safety instructions were relaxed in order to allow the launch of the shuttle, however during the countdown, before the launch, it became clear that the sensors would function properly and therefore there was no need to compromise on NASA's own safety instructions.
In total, more than 1.7 billion dollars were invested in implementing the recommendations of the investigation report into the Columbia disaster. NASA defined two flights as test flights to test the new systems installed in and around the shuttle, after which the construction of the International Space Station will continue. It is worth noting that the investigative committee severely criticized NASA for defining the space shuttles as operational instead of as tools in the experimental phase. The investigation committee insisted that the space shuttle does not deserve the title "operational spacecraft" but only an experimental spacecraft.
Discovery Mission Objectives
The STS-114 space mission was defined as an experimental mission, to examine various repair capabilities in space. The main points of the mission:
• Examining the ground and air tracking system for the space shuttle.
• Examining the camera system installed in different places on the space shuttle.
• Conducting experiments in various repair procedures in space conditions - including repairing damaged insulation tiles.
• Transferring essential supplies to the International Space Station and removing trash from it.
Problems discovered during the mission
During Discovery's mission, several incidents related to the spacecraft's thermal protection system were discovered:
• Small pieces of ceramic insulation tiles fell from various areas of the shuttle's belly.
• A large piece of insulating foam fell out of the external fuel tank.
• Insulation blankets were torn from the window area of the crew compartment.
• Insulation surfaces located between insulation tiles in the belly of the shuttle came out of place and protruded.
A significant part of these problems was identified with the help of the camera array installed in the space shuttle and with the help of the shuttle's photography from the International Space Station. The shedding of the insulating foam caused bitter disappointment to NASA engineers and Lockheed Martin, the contractor that manufactures the fuel tank. Hundreds of millions of dollars have been invested in order to understand the causes of the falling foam that caused the Columbia disaster. A large piece of insulating foam falling from a point close to the point from which the piece that hit Columbia fell was a particularly painful failure. Fortunately, this block of foam broke off in space, and did not damage the shuttle itself.
First patch in space
After examining the photographic information of the damaged areas in the space shuttle's insulation blanket, it was determined that the tears in the insulation blankets do not endanger the return of the shuttle, but it was determined that the protruding parts of the shuttle's belly must be removed. An entirely new procedure was devised to correct the problem, including the improvisation of a saw to remove the parts. An astronaut attached to the maneuvering arm of the space shuttle, and reached the lower part of the shuttle's belly - for the first time ever. It turned out that there was no need for sawing to make the repair: the astronaut pulled out the two pieces of insulating material that were sticking out, and returned them to the shuttle to examine the reasons for their release.
The falling of the insulating foam from the main fuel tank caused a storm on the ground, even before the Discovery's return. NASA has announced the grounding of the two other shuttles in its possession, Atlantis and Endeavor, until the cause of the foam fall is clarified and the defects are corrected. It should be noted that the space shuttle Atlantis was expected to take off into space in September 2005, about a month after the return of Discovery. In the history of the space shuttles there have been only three groundings: after the Challenger disaster in 1986, after the Columbia disaster in 2003, and during the Discovery mission in July/August 2005.
Postponing the next launch
After the Discovery landing, we learned about the postponement of the Atlantis launch to March 2006. The postponement was intended to allow the return of the fuel tank to the manufacturer (Lockheed Martin) in order to solve the problem of the insulation foam falling off. However, the production facility located in Louisiana was damaged by Hurricane Katrina and the launch will most likely be postponed until the end of 2006. Serious problems in the schedule of the remaining shuttle launches cast a heavy shadow on the prospect of completing the construction of the International Space Station by 2010 - the year the shuttles are taken out of service. There is a possibility that towards 2010, the pressure will increase to allow an exception of several years beyond this date, in order to complete the construction of the International Space Station and to meet NASA's obligations towards the partner countries for building the station. Of course, such a decision would have serious safety implications.
The future of the space shuttle
In January 2005, NASA announced that it had decided to develop a new generation of launchers and spacecraft, based on space shuttle technology, which would eventually bring American astronauts to the moon and serve as a stepping stone for manned missions to Mars, according to the Bush vision for space exploration. At the moment, conflicting voices can be heard in the USA - some are calling for the extension of the use of the space shuttles beyond 2010, and there are those calling for the opportunity to postpone the launch of the next shuttle until the end of 2006 and to announce the end of the use of the space shuttles already now.
Europe, which is a senior partner in the International Space Station program, shows great displeasure with the delays at NASA, which delay the connection of the European complex to the International Space Station. Japan is also not satisfied with the current situation, which is causing the postponement of the launch date of the Japanese assembly to the space station, and it has begun to examine options to launch using Russian-made consumable launchers.
Many parties in the world are waiting for a final decision on the end of the historic role of the shuttles in space exploration, since it seems that many countries and diverse space programs are directly affected by the delay in the flight schedule of the space shuttles. It is to be hoped that a decision - in any direction - will be based on technical data and independent safety assessments, and not on a desire to continue owning an expensive prestige symbol. It must be understood that the American space shuttles were groundbreaking in many fields, and served the American space program for more than two decades, but the time has come to look honestly at the fleet of shuttles built with the technologies of the seventies - to say "thank you" to them and transfer them to a museum - and to move on with new century-old tools the twenty-first
Recommended links:
The Commission of Inquiry into the Columbia Disaster
Space Shuttle Program, NASA
Back to flight - on the NASA website
