How the Hubble Telescope Works and Its Importance for Brazilian Science

The Hubble space telescope has been, since its launch in 1990, the clearest eye humanity has on the universe. Orbiting 540 km above Earth, it escapes atmospheric distortion and delivers images that transform theories and inspire generations. This article explains, in accessible language, the principles that enable Hubble to observe distant galaxies, bright nebulae, and exoplanets, and demonstrates why its results are relevant to Brazilian researchers and students.

A historic milestone in astronomy

When the Space Shuttle Discovery placed Hubble into orbit, the scientific community already expected a qualitative leap in optical observations. Unlike ground-based telescopes, which suffer atmospheric turbulence, Hubble operates in an almost air-free environment, guaranteeing angular resolution of about 0.05 arcseconds — equivalent to distinguishing a car at 30 km distance. This capability has, over three decades, enabled verification of cosmological models, measurement of the Universe’s expansion rate, and the discovery of thousands of objects that were previously invisible.

Operating principles

Hubble follows three technological pillars: high-quality optics, precise stabilization, and advanced instrumentation. Its primary mirror, 2.4 meters in diameter, is made of ultra-rare glass polished to nanometer precision. To point the telescope, a set of gyroscopes and reaction systems maintains orientation with an error below 0.007 degrees. This stability is essential for long exposures that capture light from extremely faint objects.

Hubble orbits at an altitude that allows an orbital period of roughly 95 minutes, alternating between sunlight and Earth’s shadow. To keep the instruments at optimal temperature, a thermal insulation system and radiators dissipate excess heat. This thermal management ensures the mirror does not deform, which would compromise image quality.

On-board instruments

Throughout the mission, Hubble has received several upgrades. The main current instruments include:

• Wide Field Camera 3 (WFC3): covers ultraviolet to near-infrared, enabling studies of young stars and distant galaxies.
• Advanced Camera for Surveys (ACS): optimized for wide-field imaging, essential for mapping galaxy cluster structures.
• Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS): analyze light in spectra, revealing chemical composition and object velocities.

These instruments work together, switching between imaging and spectroscopy modes, so each target can be studied from different perspectives.

During the mission, the telescope underwent two servicing missions (1993 and 2009) that replaced electronic components and installed new instruments. These interventions extended Hubble’s lifespan, demonstrating the feasibility of on-orbit maintenance—a lesson influencing future observation satellite projects.

Data distribution and access

One of Hubble’s greatest legacies is its open-data policy. After an exclusivity period of about one year, all images and spectra are deposited in NASA’s public archive, the Mikulski Archive for Space Telescopes (MAST). This practice democratizes research: Brazilian universities can download the same data as elite institutions, analyze it with free software, and publish discoveries without relying on their own missions.

Relevance to the Brazilian scientific community

Brazil has a growing number of astrophysics groups that use Hubble as a foundation for thesis projects, supernova monitoring, and exoplanet studies. The high-resolution images serve as a reference for ground-based telescopes such as the Pico dos Dias Observatory, helping calibrate instruments and validate theoretical models. Moreover, access to Hubble’s archive fuels science outreach programs in schools, inspiring young people to pursue STEM careers.

Citizen-science platforms, like Zooniverse, involve thousands of Brazilian volunteers who analyze Hubble images to identify colliding galaxies or interstellar gas clouds. This participation expands the mission’s social impact, turning scientific data into an educational and public-engagement resource.

Challenges and future prospects

Despite its longevity, Hubble faces mechanical wear and the need for maintenance. Service missions carried out in the 1990s and 2000s replaced critical components, such as the optical corrector that fixed the aberration problem. With the arrival of telescopes like the James Webb Space Telescope, Hubble’s focus is shifting toward long-term and complementary observations, reinforcing its role as a “reference observatory.” The future of Brazilian astronomy will depend on the ability to integrate these global resources into national projects, such as building medium-size telescopes in the Northeast.

Conclusion

The Hubble space telescope is not merely a monument of American engineering; it is a scientific resource that transcends borders. Its flawless operation, combined with the open-data policy, enables Brazilian researchers to partake in discoveries that shape our understanding of the cosmos. By investing in training, processing infrastructure, and international collaboration, Brazil can turn the brilliance of Hubble’s images into knowledge that benefits all of society.