Over a period of 11 days, the crew conducted 5 spacewalks and used more than 100 specialized tools, many of which were invented specifically for the mission. That December, seven astronauts flew to the telescope onboard Space Shuttle Endeavour. 'The first servicing mission in 1993 took care of that,' says Grunsfeld. Hubble could still take pictures of the cosmos but not with the sensitivity or resolution its designers envisioned.

It suffered from a distortion called spherical aberration. When Hubble reached orbit, images revealed that the telescope’s mirror was flawed. Keeping pace with technological advances on its home planet, Hubble is very much a creature of the 21 st century.Īstronauts have done more than just upgrade Hubble. Astronauts have also replaced the telescope's aging solar arrays, batteries, gyroscopes, some reaction wheels and fine guidance sensors. Hubble now has solid-state recording devices, upgraded computers, and astronomical detectors that far outperform the older technology it originally took to space. Fast forward to the present: Almost every scientific instrument onboard the telescope has been replaced at least once. When Hubble left Earth 25 years ago it was equipped with reel-to-reel data recorders, 1980s-era microprocessors, and some of the earliest digital cameras. This has allowed Hubble to do something no other spacecraft has done before-evolve. The telescope is festooned with knobs and handrails, hinged doors, and crawl spaces fit for astronauts to visit and tinker. Hubble's designers intended for astronauts to lay hands on Hubble. 'They are a symbol,' he says, 'of a unique human-robotic partnership.' The prints Grunsfeld saw are more than chemical scuff marks, though. Initially invisible, these residues darken over time as they are exposed to solar ultraviolet radiation. The 'handprints' come from oil and silicon on the astronauts' gloves, which make an impression on Hubble's exterior foil. A ScienceCast video explores the deeper meaning of superficial 'handprints' on Hubble.Īstronauts visited the orbiting telescope five times since it was launched in April 1990, conducting 23 spacewalks to repair and improve it.

Handprints on hubble