I saw the following sentence in The Space Review, and became intrigued:
Japan’s Hagoromo lunar orbiter, deployed in 1990, reached orbit but ceased transmitting enroute.
If it ceasted transmitting en-route, how did they know it reached orbit? Usually we know where things are by monitoring the doppler profile of their broadcasts (or re-broadcasts), or they simply tell us where they think they are themselves.
Radar maybe? But I learned here that optical detection tends to win at larger distances, since sunlight gives you a kilowatt per square meter to start with.
After googling and wikipedia-ing, I read in Wikipedia's Hiten article:
On the first lunar swing-by, Hiten released a small orbiter, Hagoromo (はごろも, named after the feather mantle of Hiten), into lunar orbit. The transmitter on Hagoromo failed, but its orbit was visually confirmed from Earth.
Is there any documentation of how this "visual confirmation" was actually done? Was there someone who was actually visually looking through a giant telescope and saw this 36 cm diameter precocious nano satellite orbiting the moon about 36 billion centimeters away and shouted "Yep! I see it!" in Japanese, or English, or whichever language they use when they spot a tiny satellite in orbit around the another celestial body?
above: from Gunter's Space Page
above: from Jaxa hitorical photos (found by googling "はごろも JAXA"). Hagoromo is the little one on the left, deployed for capture into lunar orbit from Hiten on the right as it passed near the moon in its highly elongated orbit around the earth - quite a cool robotic maneuver for a nano satellite in 1990 (and that's only the beginning of Hiten's story.)
above: from http://usi.kir.jp/CIA/ISAS/USI_cia_DS.html - models (presumably) of Hagoromo sitting on top of Hiten.