Case File · Codex Investigation · No. II
CIVILIAN ORIGIN · CLASSIFIED USE

The Piccard Descent

Stratosphere to Trench Floor · The Swiss family that took human beings to the highest and lowest points on Earth — and the technology the U.S. Navy bought from them

First Reach
May 27 · 1931
Deepest Dive
Jan 23 · 1960
U.S. Navy Acquisition
1958 · Trieste
Verdict
Reader is jury
Six things you can verify yourself

Before you read another word — these are in the public record.

  1. May 27, 1931 · Augsburg, Germany. Auguste Piccard rode a sealed aluminum sphere of his own design to 51,775 feet — the first human being to enter the stratosphere. FAI Record File 10634. The valve froze. They had one hour of oxygen left when they landed.
  2. The pressurized cabin he published openly went straight to military aviation. The Junkers Ju 86P. The Vickers Wellington Mark VI. The Boeing B-29 Superfortress that dropped the atomic bombs on Hiroshima and Nagasaki. The German Type IX U-boat pressure hull. Same engineering principle.
  3. January 23, 1960 · Mariana Trench. His son Jacques Piccard and U.S. Navy Lieutenant Don Walsh descended in the bathyscaph Trieste to 35,797 feet — the floor of the Challenger Deep. The first humans to reach the deepest known point on Earth. U.S. Naval Institute · Jan 2020.
  4. The Trieste carried no imaging equipment. No camera. No photograph of the trench floor exists from the 1960 dive. The only record of what was on the bottom is the testimony of the two men inside the sphere.
  5. The U.S. Navy bought the Trieste in 1958. What it did with the vessel between 1960 and the late 1970s — the USS Thresher search, the USS Scorpion search, Operation Sand Dollar, the Project Azorian adjacency — remains, in substantial part, classified to this day.
  6. Don Walsh died November 2023. He was the last surviving human being who had personally reached the floor of the Challenger Deep with civilian-built technology. James Cameron's 2012 dive and the 2019 Vescovo dives used different vessels. The original Trieste sphere is on display at the National Museum of the U.S. Navy in Washington.
§ I · Augsburg · May 27, 1931

The First Sealed Cabin Into The Stratosphere

The balloon was released at 3:58 a.m. The valve to release hydrogen and slow the ascent froze within minutes. Auguste Piccard and his assistant Paul Kipfer had no way to control their altitude. The flight was committed to running until the sun set and the hydrogen contracted enough to lose buoyancy.

The sphere had oxygen for sixteen hours. The flight lasted seventeen.

What Piccard recorded in his diary — entries reproduced in The Piccard Descent, Appendix A — was not just the famous observation of the violet sky and the visible curvature of the Earth. It was the cosmic ray ionization counts that were the actual purpose of the flight. The romantic and the technical observations sit on the same page, in the same handwriting, in the same hour.

The sky above us was no longer blue. It was a deep, dark violet, almost black. The stars were visible at midday. The horizon, far below, was a curved line. We could see the curvature with our own eyes. — Auguste Piccard · Diary entry · May 27, 1931 · 07:30 hrs
§ II · The Technology Transfer

From Civilian Engineering To Military Application

Piccard published the design of his pressurized aluminum sphere openly in the early 1930s. He did not patent it. He believed his work belonged in the public domain.

In the political circumstances of the 1930s, the public domain was not a politically neutral space. The technology had immediate military applications, and the major powers absorbed it within years.

The Junkers Ju 86P flew high-altitude reconnaissance missions over the United Kingdom in the late 1930s with a sealed pressurized cabin descended directly from Piccard's published engineering. The Vickers Wellington Mark VI flew reconnaissance missions over occupied Europe from 1942. The Boeing B-29 Superfortress — the largest American bomber of the Second World War, the first U.S. operational aircraft with a sealed pressurized cabin, and the aircraft that dropped the atomic bombs on Hiroshima and Nagasaki — was a direct descendant.

The same engineering principle was applied, in inverted form, to submarine pressure hull design. The German Type IX U-boat pressure hull, and the pressure hull of the bathyscaph that would take Jacques Piccard to the bottom of the ocean in 1960, came from the same engineering tradition.

The civilian inventor did not direct any of this transfer. He published. The militaries absorbed.

§ III · The Trieste · Challenger Deep

What Two Men Saw At The Bottom Of The Ocean

The descent began at 8:23 a.m. local time on January 23, 1960. Two men were inside the sphere: Jacques Piccard, civilian, and U.S. Navy Lieutenant Don Walsh. They were the only humans on the dive. They were committed for what would be five hours of descent and approximately eight hours total.

At approximately 9,000 meters of depth, the outer Plexiglas window of the access tunnel cracked under pressure. The pressure sphere itself remained intact. The men conferred and continued. There was no way to know if the crack would expand during the ascent and trap them inside.

They reached the floor at 1:06 p.m. The depth gauge read 11,521 meters. The actual depth, recalibrated later, was approximately 10,916 meters — 35,797 feet. They were the first human beings ever to reach the deepest known point on Earth.

Lying on the bottom just beneath us was some type of flatfish, resembling a sole, about one foot long and six inches across. Even as I saw him, his two round eyes on top of his head spied us — a monster of steel — invading his silent realm. — Jacques Piccard · Seven Miles Down · 1961

The flatfish observation has been disputed by the marine scientific community for sixty years. The biophysical maximum depth for vertebrate fish, as currently understood, is approximately 8,500 meters. The Piccard observation, at 10,916 meters, would be impossible by present consensus. There is no photograph. The Trieste carried no imaging equipment.

Don Walsh, asked about the observation in 2012 — fifty-two years later — qualified it. "Our knowledge of biology was limited," he said. He did not retract the observation. He did not insist on it.

§ IV · The Vessel Vanishes Into Classification

Post-1960 · What The Trieste Was Actually Used For

After the Challenger Deep dive, the Trieste did not become a public oceanographic vessel. It was not retired to a museum. It was not turned over to civilian deep-sea research. It was, for the next two decades, operated by the United States Navy in a series of missions whose details are partially declassified, partially still classified.

In 1963, the Trieste searched for the wreck of the U.S. Navy nuclear submarine USS Thresher, lost with all 129 hands. The complete operational record is partially classified.

In 1968, the Trieste II searched for the U.S. Navy nuclear submarine USS Scorpion, lost with all 99 hands. The complete operational record is partially classified.

Throughout the 1960s and 1970s, the Piccard-derived submersibles operated under U.S. Navy Cold War deep-ocean intelligence programs grouped under the cover designation Operation Sand Dollar. The 1974 CIA Project Azorian recovery of portions of the Soviet submarine K-129 from 4,900 meters used Piccard-derived submersible technology and personnel.

The publicly available record acknowledges the general categories of operation. The specific missions, in their full detail, are not.

§ V · Primary Documents Reproduced In The Book

Every Source Named. Every Document Excerpted.

1931
Auguste Piccard · Diary Entries
From the original handwritten notebook held in the Piccard family archive, Cully, Switzerland. Selected entries from the May 27, 1931 stratospheric flight — instrument readings, observations of the curved horizon, the frozen valve, the landing on the Gurgl glacier.
1931
Popular Science · "Up Where The Air Is Thin"
August 1931 issue. Public domain. The principal contemporary popular-press account of the flight, including the details that the international press had given the two men up for dead during the long uncontrolled drift across Bavaria, Austria, and Italy.
1961
Jacques Piccard · Seven Miles Down
First-person account of the January 23, 1960 Challenger Deep descent. Excerpts on the descent, the cracked Plexiglas, the bioluminescence, the trench floor, and the flatfish observation.
1960–2023
Don Walsh · Testimony & Interviews
Captain Don Walsh's accounts of the dive spanning sixty years, including his 2012 qualification of the flatfish observation in the Biological Bulletin and his final 2024 IEEE Spectrum interview recorded shortly before his death.
1958–84
U.S. Navy · Trieste Operational History
Public-record summary of the vessel's operations including the 1963 USS Thresher search, the 1968 USS Scorpion search, Cold War deep-ocean operations under Operation Sand Dollar, and the 1974 Project Azorian adjacency.
1961
Wolff · "The Deepest Recorded Fishes" · Nature
The first published scientific community response to the Piccard-Walsh flatfish observation, by Danish marine biologist Torben Wolff. The basis for sixty years of subsequent scientific skepticism toward the 1960 observation.
The Full Investigation
The Piccard Descent · Codex Case File No. II
123 pages · 7 chapters · 6 primary-source appendices · PDF + EPUB
Reader Is The Jury
The Codex does not adjudicate. We surface the documents, name the sources, and hold the record open. What the reader does with it is the reader's choice.