Conserving Ad Astra

While the Museum’s conservation team carries out most of our work indoors, we had the opportunity to step out of the lab for a few months and give some attention to the Ad Astra sculpture. Normally standing 113 feet tall at the Jefferson Drive entrance on the National Mall, the piece was deinstalled to allow for work to proceed on the Museum’s renovation project. Ad Astra was re-located to the Steven F. Udvar-Hazy Center where the conservation team took time to examine, document, and carry out treatment work while the sculpture was more accessible. 

History

Ad Astra was commissioned by astronaut and former Museum director Michael Collins as part of the construction of the Museum building on the National Mall in the 1970s. Created by artist Richard Lippold and installed in 1974, the towering sculpture reflects the soaring ambition of humanity to explore the unknown reaches of space. The sculpture is formed from a stainless-steel internal structure with three fins that taper to a point at the top of the spire. The outer fins are capped with stainless steel panels, some polished to a mirror finish and some treated with a unique electrochemical process that creates a golden appearance on the surface. Fixed near the top of the sculpture is a ring of three starbursts formed with stainless steel tubes. The main support was manufactured in two halves, with the upper and lower spires being joined together during the installation and the base anchored with 36 stabilizing bolts set into concrete.

Nearly 50 years later, with the ongoing renovation of the Museum in D.C., it was necessary to deinstall Ad Astra temporarily for the construction of a redesigned entry way. The sculpture was carefully removed in sections (a reversal of the original installation process) and transported to the Udvar-Hazy Center in Chantilly, Virginia, for storage until it could be returned to its home along the National Mall. This created an opportunity for the conservation team to examine the sculpture up close and conveniently on the ground.

Conditions and Challenges

Examination showed that the main structure of the sculpture was in good shape but that after years of exposure to rain and pollutants from an urban environment, an oxidation layer developed on the surface that turned the mirror polish finish dull and hazy. Oxidation is the technical name for corrosion products like rust that form on metal surfaces under certain conditions when they get wet or dirty. Along the seams between the outer and inner cover panels where water and dirt could pool, a thicker, crusty layer of oxidation built up creating dark horizontal stripes that disrupted the artist’s intent of an uninterrupted vertical ascent to the stars.

The inherent qualities of the gold finish made it tricky to come up with a treatment plan. The usual method for reducing oxidation is by applying a polish that abrades and removes the surface layers to reveal bright new metal underneath. However, the gold surface on the central panels is a durable but thin layer created by a unique chemical treatment that is impossible to replicate once lost. Nearly all traditional metal polishes are too abrasive and would lift enough surface metal to strip away the gold finish. We had to find a polishing product abrasive enough to remove the crust but not so abrasive that it would affect the gold finish. After testing different products and methods, our team found success with a polish generally used on plastic surfaces. Since plastic is much softer than metal, the polish compound is not as hard as in metal polishes, but it was strong enough to remove the crusty oxidation lines.

Treatment

Treatment work began in March 2024. We had a lot of ground to cover, and the seam crust was tenacious, so it was all hands on deck for cleaning and polishing the sculpture. Using a combination of cotton swabs, bamboo sticks, and plastic scraping tools to apply the chosen polish, we reduced the black, crusty oxidation on the gold panels.  This technique worked well, and we removed the crust from 45 seams in total. Because the sculpture is tapered, each seam on a face was a different length, so while some cleaned up quickly, some seams took as long as three days to clean! With teamwork we were able to complete the seam polishing in about two months. Since the silver panels have no electrochemical finish, they could withstand polishing with more typical metal grade polish systems. On these panels we completed two rounds of polishing, using a finer grit for the second pass to bring the finish closer to a fine mirror appearance. The starburst clusters also got a polish treatment, largely completed by our talented team of volunteers who were kind enough to brave the elements with us.

Reinstallation

The immense weight and height of the sculpture required careful planning and reinforcement measures to ensure it was reinstalled safely and accurately. The return downtown was a multi-phase operation requiring the efforts of engineers, riggers, welders, art handlers, and stone masons. Incredibly precise measurements were necessary to line up the new set of mounting bolts. The lower spire went in first followed by the upper spire with the starbursts attached, just like the initial installation in 1974.

Outcome

The rare opportunity to have complete access to this monumental sculpture allowed the conservation team to create a comprehensive condition report and perform treatments on this work of art that would otherwise have been impractical. The surface qualities that define the appearance of the sculpture also presented unique challenges in devising a treatment method that was practical and effective. Borrowing methods and products from other materials and applying them in new ways highlights the kind of “outside the box” solutions that our conservation team devise on a regular basis to serve the needs of our unique collection.