was a 7 foot tall Muslim Chinese eunuch. Which, in of itself, is not historically noteworthy.
His appearance, and paradoxical religious and ethnic combination may have made him noteworthy in his own time. In court he may have been an extraordinary figure, and knowing the Chinese court he'd likely have been mentioned by someone or other. Indeed, some specialist historian may have discovered him, if his features and traits were all he was known for.
But Zhang He explored unknown worlds.
Having trained, not since boyhood, but from his mid-twenties, when he decided being a court official was not ambitious enough, to become an astronaut he left our atmosphere at the age of 35, the upper limit for qualification.
At first, of course, he was just a regular pilot. He ran shuttle missions mostly. By the time he was 45 he had earned a minor reputation for excellence in this field. By fifty he was considered for a small exploration unit. He got the job three years later.
He spent the next thirty years penetrating deeper and deeper into space. He catalogued stars, planets, did lifesweeps, and collected samples. He charted asteroid belts and debris clouds as one would describe a reef along a rocky shore.
After this period he began to have a mid-life crisis, choosing to transfer to surface operations. These ground sweeps are generally regarded as less cozy than their ship-based counterparts, and therefore paid less.
Once he was on the surface of his first planet, however, He knew that he had picked the right job. It could take years to catalogue a single planet. The scanners on the ships could give as detailed an image as one could hope for. Yet a human was still needed on the surface to verify the machine's scanned images.
He was able to sweep three planets before retiring: FG-472, KS-096, and RD-786. To s they remain numbers, but to Zhang He they were each wildly different homes. One, arid and cold, strikingly flat until one reached a precipice and was presented an inspiring canyon vista. One, completely monopolized by a primitive multicellular seditious lifeform that fed on the surface's silicone dust and potassium-based atmosphere. One, a volcanic wonderland.
The reason his name came down to us, however, is not for his planetary discoveries, which were minimal amongst tens of thousands, but the fact that he was the first human who, after he'd retired, successfully mate with an alien life-form. In his immortal words, "It was squelchy." Their child, unsurprisingly, became World Premier. The mother looked like a rotten tree stump. He did not live to see the ceremony, passing away at 149.