Introduction

In 2015, we marked the 25th year of the Hubble Space Telescope’s journey of enabling scientific discovery and engagement of the public. Looking back to April 24, 1990, as the space shuttle Discovery lifted off from Earth with the Hubble Space Telescope nestled securely in its bay, followed by the telescope’s release into space, anticipation was high for the success of the mission. Over its history, Hubble indeed has invigorated and reshaped our perception of the cosmos and uncovered a universe where almost anything within the laws of physics seems possible.

This year, we celebrated achievements of Hubble by reflecting on the properties of space and time the observatory revealed, showcasing brand new results in a wide range of astronomical topics, and sharing its accomplishments with the public. Today, we celebrate that Hubble continues to provide views of never-before-seen cosmic wonders, and has a bright future—remaining on the forefront of key scientific topics.

As part of Hubble’s anniversary, the Institute partnered with NASA, the European Space Agency, and other institutions to highlight the observatory’s 25 years of accomplishments. The series of events kicked off in January with the release of a new multi-band image of the Eagle Nebula. This was followed by the annual science Spring Symposium and conference dinner, the showcasing of the spectacular anniversary image of the Westerlund 2 star cluster, a Hubble commemoration at the National Air and Space Museum, and other public activities such as education programs, exhibits, seminars, and multi-media and social media campaigns.

Science

In January, a new multi-wavelength image probing the Eagle Nebula from Hubble’s newest instruments kicked off the anniversary year at the American Astronomical Society meeting. The Panchromatic Hubble Andromeda Treasury (PHAT) program, which sampled about 40% of M31 in 7,398 exposures taken over 411 individual multi-color pointings, was highlighted in a 30-foot mosaic panel, and underscored in several science talks. Other topics, such as the measurement of the Milky Way Galaxy’s Fermi Bubble expansion, along with newest results on exoplanets and dark energy probes, filled out the rich science roster of the meeting.

The recent identification of an emerging class of evolved self-obscured 25−60 M stars in galaxies at ∼1−4 Mpc has for the first time created the opportunity to observationally investigate a statistically significant number of stars undergoing episodic mass loss. While our current efforts to identify these rare objects in a short-lived yet consequential evolutionary phase primarily rely on archival Spitzer IRAC (3.6−8 µm) and MIPS (24 µm) images, they can be studied far more optimally at 10 ∼ 28 µm with the Webb taking advantage of MIRI's order-of-magnitude-higher resolution.

Figure 1: Simulated clipse spectra taken from Greene et al. 2016. The spectra are for a single transit with equal time on the star alone for each of the four instruments. Spectra have been binned to resolution R ≤ 100 (hot Jupiter, warm Neptune, warm sub-Neptune) and R = 35 (cool super-Earth). The simulated spectra include a noise instance and are presented as colored curves. The black error bars denote 1σ of noise composed of random and systematic components. Dashed lines show the wavelength range boundaries of the chosen NIRISS, NIRCam, and MIRI instrument modes.

Throughout the year, striking results from scientific studies ranged from the solar system and discovery of the chaotic nature of two of Pluto’s moons, to detection of cloudy atmospheres on exoplanets, star formation and galaxy evolution, dark matter in galaxy cluster collisions, and new cosmic distance records. The 25th anniversary itself was celebrated with the Spring Symposium entitled “Hubble 2020: Building on 25 Years of Discovery.” This Symposium not only looked at some of the notable advances made through Hubble investigations, but also underscored synergies with other missions. It also highlighted the future role of Hubble in relation to the promise of the James Webb Space Telescope and upcoming facilities such as WFIRST/AFTA and the next generation of large UV optical telescopes in space.

The dramatic anniversary image of the star cluster Westerlund 2 was unveiled in Washington D.C. by NASA on the last day of the symposium. This was followed by events at the Institute with panel discussions populated by astronauts, the NASA administrator, and other individuals reflecting on the fabrication, launch, and refurbishment of Hubble over the years. The annual Bahcall Lecture, given by Prof. Robert Kirshner (Harvard-Smithsonian Center for Astrophysics) as part of the 25th Anniversary celebration, punctuated the afternoon. A conference dinner followed, with participation by Hubble astronauts, as well as key individuals from industry and the science community who have played a major role in the design, construction, launch, and in-orbit repair of the telescope. Senator Barbara Mikulski completed the festivities with a congratulatory address.

Classroom education

The core of Hubble’s success is breakthrough science, often demonstrated through dramatic imagery and widely disseminated through the literature, as well as the news media, social media, and public information channels. These results are adapted to trusted and resilient educational resources through a proven model for science, technology, engineering, and math (STEM) education. Partnerships between scientists and educational specialists result in relevant, effective, and field-tested educational tools disseminated to classrooms affecting millions of youths at a time. While supported with only a small percentage of the Hubble budget, the program enhances STEM education initiatives for over 500,000 teachers in the classrooms of over 6 million students nationwide each year.

Accordingly, Hubble’s celestial silver milestone was celebrated during anniversary week through a special nationwide teach-in program that was aired on social media and was accessible to every classroom in the nation. Students and teachers joined educators and astronomers for an online exploration of the remarkable history and bright future of the telescope to learn how astronomy and our understanding of the universe have been transformed by Hubble research.

Public exhibits

The anniversary provided a perfect opportunity to widely showcase Hubble’s scientific achievements and the vision for its future in the context of Webb and beyond. The Gallery Walk at Reagan National Airport and the Gateway Gallery at Washington Dulles International Airport now greet visitors the world over, momentarily transporting their imaginations across the universe. The Institute provided the collection of images, artifacts, and student artwork for the displays.

From a distance, the images convey an impression of the great variety of astronomical subjects observed by Hubble. Viewing them close-up, visitors are able to enjoy the great beauty of the images and learn more about their scientific significance. The display cases at Gallery Walk also house artifacts that illustrate how Hubble has become the “People’s Telescope.” The cases include tools astronauts used to service the observatory, technological spinoffs, student artwork, and elements of Hubble incorporated into popular culture. Exhibits were also ingeniously created for the captive audiences at baggage claim areas at Baltimore/Washington International Thurgood Marshall, Reagan National, and Washington Dulles International airports.

To enable numerous other sites to share in the celebration and create their own custom exhibits, the Institute created a website with source material including the “Visions of the Universe” imagery, as well as slides and images for public lectures for the general public.

A list of all the events, activities, and products in celebration of Hubble’s 25th anniversary is available at http://hubble25th.org.


Figure 3: OPO-produced airport exhibit.