OPINION: A Sun sets over Sacramento Peak: The rise and fall of a New Mexico icon

For over 70 years, the iconic white domes of the Sacramento Peak Observatory have stood like sentinels in the Lincoln National Forest, a beacon of scientific discovery against the deep blue New Mexico sky. As a historian for the Air Force Research Laboratory (AFRL), the modern successor to the Air Force Cambridge Research Laboratory (AFCRL) that founded this site, I feel a profound sense of duty to reflect on its origins, its monumental contributions and the significant scientific loss due to its possibly inevitable end.

The story of the observatory, known to many as Sunspot, is inextricably linked to the U.S. Air Force and the dawn of the Cold War. In the late 1940s, we recognized a critical vulnerability: the Sun. Solar flares could disrupt the radio communications essential for our global operations and pose a danger to high-flying aircraft. To operate effectively, the Air Force needed to understand and predict this “space weather.” In 1947, AFCRL in Massachusetts was tasked with finding the perfect location for a world-class solar observatory. After a nationwide search, a team led by Dr. John “Jack” Evans pinpointed this remote peak near Cloudcroft for its unparalleled atmospheric clarity.

Beginning in 1949, under Air Force direction, a rugged mountaintop was transformed into a frontier settlement for science. The crown jewel, the revolutionary Dunn Solar Telescope (DST), was completed in 1969. Its unique vacuum design gave humanity its sharpest-ever view of the Sun and provided the critical forecasts that supported military communications and guided NASA’s Apollo missions to the Moon.

In 1976, the Air Force, confident in the foundation it had built, transferred management to the National Science Foundation (NSF). This transition ushered in a golden age of astronomical discovery. The observatory’s mission broadened from its defense-focused origins to probe the fundamental physics of our star. Scientists from around the globe flocked to this peak, making it a vibrant international hub. They mapped the solar interior through helioseismology, studied the complex magnetic fields that create sunspots, and explored the violent dynamics of the solar corona. For decades, it was not only a premier research facility but also a vital training ground, where generations of graduate students and postdoctoral researchers first learned to decipher the secrets of the stars.

In recent years, New Mexico State University has played a pivotal role in the observatory’s operations and outreach. Through the Sunspot Solar Observatory Consortium, NMSU has managed the facility, ensuring its continued use for research and education.

NMSU has actively engaged the public through guided tours and an interactive visitor center, fostering interest in astronomy. The university’s faculty and students have been at the forefront of solar research at the observatory, investigating phenomena such as solar flares and coronal mass ejections.

The observatory has served as a critical training ground for the next generation of solar researchers, with graduate students taking leading roles in research projects.

Yet, the march of technology is relentless. In the 21st century, newer, larger ground and space-based telescopes began to eclipse the capabilities of the aging facility on Sacramento Peak.

Recognizing this, the NSF began searching for a new partner to assume long-term responsibility, hoping to keep the site active. But a viable successor could not be found.

The final, unavoidable chapter was written not by a committee, but by chemistry. In January, a liquid mercury leak was discovered within the heart of the Dunn Solar Telescope. The instrument’s massive, rotating optical platform floated on a 160-gallon bearing of liquid mercury — a design marvel in its time, but now a significant environmental hazard.

Faced with this reality, the NSF made the unfortunate decision to proceed with the full decommissioning and demolition of the site.

The complex and hazardous process of draining the mercury will render the historic telescope permanently inoperable.

Following this, the domes, towers and support buildings that have been a landmark for three-quarters of a century will be removed, and the land will be restored.

The white domes will vanish, and the peak will return to a more natural state. But its legacy is twofold and indestructible. It is a military legacy, born of a strategic need to understand our environment from the ground to the heavens that continues at AFCRL’s descendent, the Air Force Research Laboratory.

Today, AFRL continues to build on this legacy, remaining at the forefront of space weather research and development. AFRL’s space research and development facilities on Kirtland Air Force Base are a center of excellence for space technology, with a dedicated division for space weather sensing and modeling.

The new Skywave Technology Laboratory, established in 2021, further enhances AFRL's capabilities in ionospheric and radio frequency research.

Key initiatives include the Space Solar Power Incremental Demonstrations and Research project, which aims to develop space-based solar power transmission, and collaborations with NASA on missions to study the ionosphere.

Through advanced modeling, sensor development, and partnerships with academia and industry, AFRL is pioneering new technologies to forecast solar events and protect our nation’s assets in space and on the ground.

And it is a scientific legacy, written in thousands of research papers, groundbreaking scientific and technical programs and missions, and in the careers of the scientists and engineers it inspired. The physical observatory may return to the Earth, but the knowledge it unveiled will forever be a part of our journey to the stars.

Dr. Darren Raspa is the historian, archives director and U.S. Space Force integration lead for the Office of the Deputy Technology Executive Officer for Space at the Air Force Research Laboratory.