Beginning October 26th, a team of engineers from NASA and the European Space Agency (ESA) will test one of the Hubble Space Telescope’s new solar arrays. This test will ensure that the new arrays are solid and vibration free before installation on the next servicing mission, currently scheduled for November 2001.

The test will occur at ESA’s European Space Research and Technology Center (ESTEC) in Noordwijk, The Netherlands. ESA’s test facility features a huge vacuum chamber with bright lights that simulate the Sun’s intensity including sunrise and sunset. By exposing the solar wing to the light and temperature extremes of Hubble’s orbit, engineers will use the data to anticipate how the new set of arrays will function in space. The ESTEC facility was chosen as the site for the test because it is the only chamber that has a solar simulator with the proper capabilities for the test and is big enough to accommodate the size of the new solar array.

Hubble orbits the Earth once every 90 minutes. During each orbit, the telescope experiences 45 minutes of searing sunlight and 45 minutes of frigid darkness. This test will detect any tiny vibrations, or jitter, caused by these dramatic, repeated changes. Even a small amount of jitter can affect Hubble’s sensitive instruments and interfere with observations.

Hubble’s first set of solar arrays experienced mild jitter and was replaced in 1993 with a stable pair. Since that time, advances in solar cell technology have led to the development of even more efficient arrays. In 2001, NASA will take advantage of these improvements by fitting Hubble with a third-generation set of arrays. Though smaller, this new set generates more power than the previous pairs. The arrays use high efficiency solar cells and an advanced structural system to support the solar panels. Unlike the earlier sets, which roll up like window shades, the new arrays are rigid.

The new solar arrays were assembled in-house at the Goddard Space Flight Center, Greenbelt, Md. by a team of NASA and industry engineers. ESA provided Hubble’s first two sets of solar arrays, and they built and tested the motors and electronics for the new set. The NASA /ESA test can benefit the aerospace community by expanding knowledge on jitter phenomenon. As a result of these findings, engineers will be able to apply this information to future spacecraft.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency.