Veteran NASA astronaut Don Pettit, with nearly six hundred days of spaceflight experience, recently gained unparalleled access to all 1.2 million raw files from his latest International Space Station expedition. Among this vast collection is a truly breathtaking image of the Milky Way, captured from the station's iconic Cupola using a Nikon Z9 camera paired with an Arri Zeiss 15mm lens. What makes this photograph particularly striking is how the stars appear utterly motionless, as if the station itself were suspended in the cosmic void. This visual paradox belies the reality: the ISS is in fact hurtling through space at an astonishing 27,000 kilometers per hour, all while maintaining a constant orientation to keep one side perpetually facing Earth.
Star trails above and below Madagascar, photographed together from the ISS and Earth in collaboration with National Geographic's @BabakTafreshi.
This continuous Earth-facing alignment, while crucial for operations, presents a significant challenge for long-exposure astrophotography, inevitably transforming distant stars into elongated trails. On Earth, astronomers use equatorial mounts to counteract our planet's diurnal rotation, keeping celestial objects fixed. Pettit, however, recognized that an orbital environment demanded a different solution—a device capable of completing a full rotation every 90 minutes, mirroring the ISS's orbital period. This led to the creation of a bespoke star tracker at the Rochester Institute of Technology (RIT). Remarkably, this tracker was purely mechanical, crafted from aluminum, and driven by a spring and a 60:90 gear ratio. This non-electronic approach cleverly bypassed NASA's stringent regulations concerning electrical systems on cargo payloads.
Following its successful deployment and operation during Expedition 72, the innovative device made a triumphant return to Earth and is now slated for exhibition at RIT, offering a tangible piece of space history. Pettit himself recalls a poignant memory of a similar, earlier homemade tracker from Expedition 6, which met a fiery end, incinerated along with other station waste during atmospheric re-entry. This time, fortunately, the narrative unfolded differently, a testament to meticulous planning and engineering.
The images produced with this mechanical marvel vividly illustrate the fine line between perceived motion and absolute stillness. A 10-second exposure without the tracker, for instance, renders stars as blurred, indistinct streaks. Yet, with the tracker engaged, those same stars remain sharp, pristine pinpricks of light. Pettit's work extended beyond individual captures; he later collaborated with acclaimed National Geographic photographer Babak Tafreshi. Together, they published images showcasing star trails simultaneously captured above and below Madagascar—one set from orbit, the other from Earth's surface. More recently, Pettit released a captivating timelapse documenting an optimal fuel maneuver, during which the station subtly reoriented itself over the luminous cityscapes of the Mediterranean.
Having accumulated 220 days in orbit across Expeditions 71 and 72, and completing over three and a half thousand circuits around our planet, Pettit views photography as more than just a hobby. For him, it's a profound medium to share the unique perspective of our home planet from afar, serving as a powerful reminder that the cosmos is far more accessible and intertwined with our existence than we often perceive. The mechanical star tracker, which metaphorically "stopped" the stars for a moment in time, has now itself become an indelible part of space exploration history.
