Hubble Space Telescope

Hubble Space Telescope

Abstract

This paper addresses the architecting process of the Hubble Space telescope. The focus will be on the heuristics of the Hubble. We will examine the development of the Hubble, from modeling to simulation to make sure the design is appropriate for the desired performance.

Next we will discuss the economics and politics driving the project. In any high profile program the political and economic pressure does affect the direction the program is ultimately headed.

The discussion will continue with the heuristics used to address the mishaps along the way. Finally it will end on how the resilience of the engineer and architect team pushed Hubble into a successful story. In a complex system like the Hubble, the heuristic approach can be problematical. This paper will explore the problem solving techniques.

Introduction

The Hubble Space Telescope (HST) is the iconic telescope that has opened our eyes to the universe. It has expanded our understanding about galaxies, and introduced us to massive forces that we never knew existed. Among the discoveries and observations made by the HST are the determinations of Hubble’s constant, the existence of dark energy, accelerating cosmic expansion, and the convergence of galaxies. The powerful lens sees everything, and is the key responsible for unlocking some of the greatest mysteries of the universe. The purpose of having a telescope in space is to capture images without Earth’s atmosphere distorting the images. Over the years HST has proven to be one of NASA’s most successful and enduring science missions. The telescope, named after astronomer Edwin Powell Hubble, was finally launched in April 1990 into a low earth orbit (LEO) after experiencing many delays due to financial and political constraints.

After seeing the impact the Orbiting Astronomical Observatory (OAO); has had to astronomy it was clear time and money should be invested into taking it to the next level. The OAO has shown the potential of a space based telescope and the possibilities of what can come from a more advanced telescope were an exciting idea to the scientific community. It took years of planning and even more time raising the funds to back the program.

Conceptual Process

Since the days of Galileo we have sought to see what is in the apparent darkness. For hundreds of years ground base telescope have only scratched the surface of what can be seen. In 1946 Lyman Spitzer Jr. had proposed developing a space based observatory. The main advantage of having a telescope is space is to prevent the air pockets in Earth’s atmosphere from distorting the view. Also some wavelength of radiation gets absorbed by the atmosphere before it even reaches Earth. The best way of studying objects in space is to examine the wavelength that particular object emits.

Technological advances have led to ground based telescopes that account for atmospheric distortion and corrects the problem, however we still cannot see the wavelength that never makes it through. The best way to continue studying the Universe is to place a telescope above the atmosphere. This way infrared, ultraviolet, gamma rays, and x-rays can be detected and analyzed. This idea was accepted by the scientific community and 1975 the European Space Agency (ESA) and NASA had began to develop a plan for what would eventually be the Hubble.

Economic and Politics

The more difficult step is to obtain federal funding for Hubble. To convince congress to approve an estimated 400-500 million dollars to fund the project would be a tough sell. Financial support as expected was rejected as the need and benefits were not apparent to congressman and senators. This prompted a legion of hopeful astronomers to meet with elected officials to highlight the need for a space based telescope and benefit it would bestow not only in the astronomy community, but the science community as a whole. Although originally rejected NASA established the scientific goals of the mission and emphasize how important it would be to press forward with the project. Congress eventually reviewed the new proposal and questioned need for certain instruments. After deciding to go with less expensive instruments and a cheaper set of solar panels Congress eventually approved the program in 1977.

The politic behind the funding for Hubble caused a modification from the original concept design. As congress tried to keep cost low many items were cut or downsized to balance the budgeted amount for the program. The most eminent was the reduction of the primary mirror. The larger the mirror the more light it can absorb so this definitely affected the capabilities of the system (This will be address in more detail in the design and construction segment of the paper). The configuration of the telescope was downsized in hopes of having a more efficient assembling process. In fact to mitigate the financial risk the ESA was brought into provide knowledge and funding. This heuristic is that applies here is:

“Risk is defined by the beholder, not the architect” (Rechtin, 1991 pg 264). 1

The ESA agreed to support the first generation of equipment and the solar array that would supply power to the telescope. In return the NASA and United states politician agreed to provide European astronomers 15% of the viewing observation time. This is a risk mitigation and compensation strategy. This distributes the financial burden and the benefits Hubble would provide. NASA found a way to reduce the financial investment and the inherent risk that goes along with it by diversifying the workload. This is something the engineers would not see as they are consumed with developing the best product they can; it would be difficult for them to acknowledge the risk in the program.

Design and Construction

After Congress approved funding, work on the Hubble had begun. Given that it is such a complex system it would require multiple entities to design and manufacture the telescope. This is in accordance with the heuristic:

“A system architecture cannot be considered complete lacking a suitable match with the process architecture” (Rechtin, 1991 pg 132). 1

Every contractor working on the Hubble shall be applying their expertise to the program. It would not make sense for a Goddard Space Flight Center to build the optics for the telescope when they specialize in instruments. NASA and ESA divided the main work among four institutions: Goddard Space Flight Center was tasked with