Omega
Speedmaster Tritium Big S Caliber 861 - Stainless Steel

Omega Speedmaster Professional Moonwatch reference 145.022, 1991 example, 42 mm asymmetrical stainless-steel case, 20 mm lug width, matt black “Big S” three-register dial with tritium hour markers and hands, small seconds at 9 o’clock, 30-minute counter at 3 o’clock, 12-hour counter at 6 o’clock, central chronograph seconds, fixed black tachymeter bezel, domed Hesalite crystal, non-screw-down crown and chronograph pushers, solid screw-down stainless-steel caseback carrying the inscriptions connected with the Speedmaster’s space qualification, original Omega stainless-steel bracelet with signed folding clasp, Omega calibre 861 hand-wound mechanical chronograph movement, cam-operated chronograph with horizontal clutch, frequency of 21,600 vibrations per hour, 17 jewels, approximately 42-hour power reserve after full winding, watch inspected and authenticated by the Mostra workshop, supplied with an Omega service box, Mostra Certificate of Authenticity and Mostra 3-year warranty.

“Some watches have been made famous by history, while a much smaller number have ultimately become part of history itself. The Speedmaster belongs to this second category. Born to measure speed beside racing circuits, selected only a few years later to accompany astronauts, transformed into the Moonwatch and then into the chronograph of the space programmes that followed Apollo, it has preserved the essentials of its design for more than half a century. This 1991 145.022 reminds us why: a black dial, three registers, a tachymeter bezel, a Hesalite crystal and a movement that still has to be wound each morning. Few watches create such a direct link between an everyday gesture and a story that became universal.”

The 1991 Omega Speedmaster Professional 145.022 belongs to one of the most appealing periods of the Moonwatch. It retains all the visual elements that created the legend — the 42 mm asymmetrical case, Hesalite crystal, black three-register dial, tachymeter bezel and solid caseback — while being powered by the calibre 861, the movement that continued for several decades the mechanical history begun with the calibre 321. Its tritium dial and “Big S” typography now place it clearly within the neo-vintage world: old enough to have developed the warmth of material that contemporary watches so often attempt to recreate, yet mechanically modern enough to remain regularly wearable when properly maintained.

The story begins in 1957, when the first Speedmaster CK2915 appeared as a chronograph intended for motor racing and sport. One of its major visual innovations was moving the tachymeter scale from the dial to the bezel, freeing the display and giving the watch an immediately functional identity. Nothing at that stage suggested it would become a space watch. Yet only a few years later, the robustness, readability and simplicity of its mechanics would take the Speedmaster far beyond the racetrack. In 1962, a Speedmaster accompanied Walter Schirra into space; in 1965, NASA officially selected the model following a particularly demanding series of tests. The Speedmaster became an instrument of the American space programme before Buzz Aldrin wore one on the lunar surface in July 1969. From that moment, Moonwatch ceased to be merely a commercial nickname and became the summary of a genuine historical achievement.

This 1991 watch must nevertheless be placed accurately within that chronology. It is obviously not one of the Speedmasters that participated in the lunar missions of the 1960s and 1970s. Its significance is different: it belongs to the direct lineage of those watches, retaining an exterior architecture of remarkable continuity and, above all, the calibre 861 introduced from 1968 as the successor to the legendary 321. The 145.022 family carried the Speedmaster beyond the first Moon landing, through the later Apollo era and into Skylab, Apollo-Soyuz and, above all, the Space Shuttle programme. In 1978, the calibre-861 Speedmaster was again qualified in connection with NASA requirements for Shuttle missions. The Moonwatch story therefore did not end with Apollo 11: it continued, and calibre 861 became one of its principal mechanical threads.

The black “Big S” tritium dial gives this example a personality that modern Speedmasters cannot reproduce exactly. The broader, more open initial letter of the Speedmaster signature is one of those details that may appear insignificant at first sight yet allows enthusiasts to identify a production period almost immediately. Around it, the register arrangement remains the one that made the Speedmaster a benchmark for legibility: small seconds at 9 o’clock, 30-minute counter at 3 and 12-hour totaliser at 6, completed by the long central chronograph hand. The hour markers and hands were originally filled with tritium, a material that naturally evolves with age and can develop shades ranging from pale beige to cream. This evolution must always be judged through the coherence of the entire watch rather than the intensity of patina alone: on a vintage Speedmaster, beauty often lies in the way dial, hands and luminous material have travelled through the decades together.

The 42 mm asymmetrical case has become almost as famous as the dial itself. Its lateral protection surrounds the crown and pushers without making the watch appear bulky, while the twisted lugs alternate polished and brushed surfaces. The dimensions may appear substantial on paper, yet the shape of the case and the position of the dial make the Speedmaster remarkably balanced on the wrist. It remains sporty enough on its steel bracelet for denim, a jacket or travel clothing, while the highly graphic black dial also allows it to work naturally with a shirt or tailored jacket. This is one of the secrets of its aesthetic longevity: the Speedmaster has never needed to become a dress watch in order to be elegant.

The Hesalite crystal contributes directly to that identity. More susceptible to scratches than sapphire, it offers a warmth and slight distortion around the edge of the dial that have long been part of the Moonwatch experience. Its use is also connected with the watch’s space history: on watches selected for crewed missions, avoiding potentially dangerous fragmentation from a mineral or sapphire crystal was advantageous in a confined environment. Today, Hesalite simply requires a little more care and can generally be polished when fine scratches appear. Above all, it reminds us that this Speedmaster remained faithful to a conception in which use dictated the material before luxury transformed that material into an aesthetic argument.

Surrounding the crystal, the black tachymeter bezel recalls the model’s motor-racing origins. Used with the chronograph over a known distance, it can calculate average speed, the function that explains the name “Speedmaster” long before the conquest of space. The chronograph itself remains controlled by two conventional pushers: start and stop at 2 o’clock, reset at 4. It is not a mechanism designed to impress by multiplying functions; it was created to measure elapsed time clearly. More than sixty years after the birth of the Speedmaster, this arrangement remains one of the most legible chronograph interfaces ever designed.

Beneath the solid caseback works the Omega calibre 861, the historical heart of this example. This hand-wound mechanical chronograph movement operates at 21,600 vibrations per hour, or 3 Hz, contains 17 jewels and provides approximately 42 hours of power reserve after full winding. It replaced the column wheel of calibre 321 with a cam-operated chronograph mechanism combined with a horizontal clutch. This architecture enabled a rational, robust construction particularly well suited to a chronograph intended to be used rather than merely admired. Each morning, a few turns of the crown are enough to tension the mainspring again: a very simple gesture that creates a surprisingly strong relationship with the watch. A hand-wound Speedmaster does not merely indicate time; it asks its owner to return a little energy to it every day.

This example is fitted with its original Omega stainless-steel bracelet and signed folding clasp, a configuration that fully preserves the instrumental character of the Moonwatch. Steel reinforces the professional nature of the case and gives the watch the slightly industrial presence that suits the Speedmaster so well. Replace the steel with black or brown leather, however, and the watch changes register completely. Few chronographs move so naturally from a steel tool-watch bracelet to a more formal leather strap without losing their identity. The bracelet therefore forms part of the pleasure of using the model: the same Speedmaster can be a space watch in the imagination, a sporting chronograph in its design and an urban watch in real life.

Water requires a deliberately cautious approach. A Speedmaster of this generation is not a diving watch and its pushers are not screw-down. Whatever historical water-resistance specification was associated with Moonwatch construction, a 1991 example should never be considered suitable for immersion solely on the basis of an old catalogue value. At Mostra, use in water depends exclusively upon a recent inspection of the seals and case; with a vintage Speedmaster, we prefer a conservative approach in order to protect the dial, tritium and movement.

The fact that this watch is accompanied by an Omega service box is also described precisely: this is not its original 1991 presentation box and the watch is therefore not presented as a Full Set. The official Omega service box nevertheless provides an entirely appropriate environment in which to store or transport it. On a Speedmaster more than thirty years old, collector value rests above all on the coherence of the watch itself: dial and hands, tritium, bezel, pushers, crown, caseback, bracelet, case geometry, movement and the quality of previous interventions. A fine Speedmaster is never judged from a single component; it must be read as a complete object in which every detail tells the same period story.

It is precisely here that Mostra has developed particular expertise in the Speedmaster. For more than forty years, we have examined, bought, sold and maintained Omega chronographs from the different generations: calibres 321, 861, 863, 1861 and more contemporary variations. Regular familiarity with the model makes it possible to understand differences in dials, typography, bezels, casebacks, bracelets and service components that can completely change the interest of an individual watch. Mostra Magazine also devotes several features to the Moonwatch, including a dedicated article on the Speedmaster 145.022 and calibre 861, allowing the history of this watch to continue beyond its product page: https://www.mostra-store.com/en/magazine/the-omega-speedmaster-861-145022-a-legend-of-space-exploration

Choosing this 1991 Omega Speedmaster Professional 145.022 from Mostra therefore means benefiting not only from more than forty years of experience in collectible watches, but also from an integrated watchmaking workshop in Aix-en-Provence accustomed to inspecting these chronographs. Winding operation, rate and amplitude of calibre 861, power reserve, chronograph start, stop and reset, hand alignment, pusher condition, coherence of the “Big S” dial, tritium, bezel, Hesalite crystal, caseback and bracelet all receive specific attention. Mostra’s verified customer reviews carry a 5-star rating; this Speedmaster is supplied with its Omega service box, a Mostra Certificate of Authenticity and our 3-year warranty, together with the continued support of our workshop.

The 1991 Speedmaster 145.022 ultimately possesses a quality achieved by very few watches: it can be studied for hours by a collector while remaining extraordinarily easy to love. Forty-two millimetres of steel, a black dial, three registers, a Hesalite crystal and a calibre 861 wound by hand: the object itself is almost austere. Yet behind that simplicity lie the motor-racing circuits of the 1950s, NASA, Apollo, Skylab, the Space Shuttle and more than half a century of watchmaking continuity. At Mostra, it is precisely this historical depth that we seek to preserve whenever a Speedmaster passes from our workshop to the wrist of its next owner.