FACULTY OF COMPUTER SCIENCE AND MATHEMATICS
SOFTWARE IMPROVEMENT
ITS 473
CASE STUDY REPORT:
European Space Agency’s Ariane 5 Explosion
NAME
MATRIC NO.
Muhammad Aiman Bin Abdul Razak
2018292398
Ahmad Mahyudi Bin Muhamad Fitri
2018400518
Mohd Shahrul Amir Bin Shaari
2018440492
Abdul Mu’min Bin Masuhur
2018674294
GROUP: CS246 3A
PREPARED FOR:
MADAM MASLINA BINTI ABDUL AZIZ
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Table Content
1. Introduction
3
2. Overview
4
3. Aftermath
6
4. Cause of Failure
7
5. Effects on Environment
9
6. Involvement
10
7. Lesson Learnt and Prevention
11
8. References
12
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1. Introduction
Arianespace’s Ariane 5 is the world reference for heavy-lift launchers, able to carry payloads
weighing more than 10 metric tons to geostationary transfer orbit (GTO) and over 20 metric tons
into low-Earth orbit (LEO) – with a high degree of accuracy mission after mission. This performance
ensures that Ariane 5 will be able to loft the heaviest spacecraft either in production or on the
drawing boards, and enables Arianespace to match up most telecommunications satellites for
highly efficient dual launches – a capability that has been proven by the company in Ariane-series
missions since the 1980s.
An Ariane 5 rocket preparing for launch
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2. Overview
On 4 June 1996, the maiden flight of the Ariane 5 launcher ended in a failure. Only about 40
seconds after initiation of the flight sequence, at an altitude of about 3700 m, the launcher veered
off its flight path, broke up and exploded. Ariane 5 was developed by European Space Agency (ESA)
that took around 10 years of research and $7 billion on budget. Ariane 5 rockets are manufactured
under the authority of the European Space Agency (ESA) and the French spatial agency Centre
National d'Etudes Spatiales (CNES).
The rockets are launched by Arianespace from the Guiana Space Centre in French Guiana.
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The rocket was carrying 4 satellites to launch into Orbit in order to study Earth’s magnesphere.
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3. Aftermath
Following the failure, four replacement Cluster II satellites were built. These were launched in pairs
aboard Soyuz-U/Fregat rockets in 2000. The launch failure brought the high risks associated with
complex computing systems to the attention of the general public, politicians, and executives,
resulting in increased support for research on ensuring the reliability of safety-critical systems. The
subsequent automated analysis of the Ariane code (written in Ada) was the first example of largescale static code analysis by abstract interpretation. The failure also harmed the excellent success
record of the European Space Agency's rocket family, set by the high success rate of the Ariane 4
model. It was not until 2007 that Ariane 5 launches were recognised as being as reliable as those
of the predecessor model.
Recovered support strut of the satellite structure
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4. Cause Of Failure
The Ariane 5, in contrast to the previous model had a fundamentally different scenario of pre-flight
actions — so different that the work of the fateful software module after the launch time made no
sense at all. However, the module was used again without any modifications.
This confidence was supported by the evaluations, showing that the expected range of physical
parameters that was taken as the basis for the determination of the values of the mentioned
variables can never lead to an undesirable situation. And it was true — but for the trajectory
evaluated for Ariane 4.
The new generation Ariane 5 rocket launched on an entirely different trajectory, for which no
evaluations were carried out. Meanwhile, it turned out that the “horizontal velocity” (together
with the initial acceleration) exceeded the estimated (for Ariane 4) more than five times.
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Report by the ESA on the cause of rocket failure
After the incident, many were criticizing the Ada programming language for being primarily responsible
for the Operand error. A “language war” broke out between supporters – and gurus – of Ada and Eiffel.
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5. Effects on Environment
The shuttle was unmanned resulted in no loss of life and hence no legal actions were taken against
anyone according to official records. Another issue that followed the accident, an ethical one, was
the environmental damage. ESA had well formed plans for such a case.
The combustion gases from the solid boosters during the atmospheric flight consist of hydrochloric
oxide, aluminium oxide, carbon monoxide and carbon dioxide.
The results showed that a hydrochloric acid and aluminium oxide fallout occured within a
500m radius of the launch pad. No gaseous pollution at ground level was detected by any of
the measuring instruments outside the launch area. The helicopter monitoring the gases from
the explosion after three hours reported that the gases were moved several kilometres off
coase and were dissipating gradually.
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6. Involvement
The National Centre for Space Studies (CNES) is the French government space agency
(administratively, a "public administration with industrial and commercial purpose").
•
Helped in developing the Ariane 5
•
In charge of investigating the causes of the explosion
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The chairman sets up an independent Inquiry Board and nominated the members to
investigate the tragedy specifications.
The European Space Agency (ESA) is an intergovernmental organisation of 22 member states[6]
dedicated to the exploration of space.
•
Approves the budgets
•
Oversees project progress
•
Monitor costs on completion
•
Manages schedules
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7. Lesson Learnt and Prevention
Don’t run software in critical systems unless it is actually needed. As well as testing for what the
system should do, you may also have to test for what the system should not do. Do not have a
default exception handling response which is system shut-down in systems that have no fail-safe
state.
Lessons learned In critical computations, always return best effort values even if the absolutely
correct values cannot be computed. Wherever possible, use real equipment and not simulations.
Improve the review process to include external participants and review all assumptions made in
the code. The design and code of all software should be reviewed for problems during the
development process.
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8. References
Prof. J. L. LIONS (19 July 1996). ARIANE 5, FLIGHT 501 FAILURE from http://wwwusers.math.umn.edu/~arnold/disasters/ariane5rep.html
Jamie Lynch (7th September 2017). The Worst Computer Bugs in History: The Ariane 5 Disaster
from https://blog.bugsnag.com/bug-day-ariane-5-disaster/
Edwin McDowell (5 May 1987). European Failure Leave Space Effort Mired in Frustation from The
New York Times https://www.nytimes.com/1987/05/05/science/european-failures-leave-spaceeffort-mired-in-frustration.html
European Space Agency, Office of the Director General, “Inquiry Board Report: Ariane 5 Flight 501
Failure”, Paris, France, July 19, 1996. http://sunnyday.mit.edu/nasa-class/Ariane5-report.html
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