The International Space Station is currently observable at unsocial pre-dawn hours but will reappear in our evenings from 19 April, 10 days before the scheduled launch date of the shuttle Endeavour. This is the 25th and final mission of Endeavour which was the last shuttle to join Nasa's fleet. Along with spares and supplies for the ISS, the flight will deliver the Alpha Magnetic Spectrometer, a cosmic ray detector that may provide evidence for dark matter.
Meanwhile one of the brightest but most secret of the satellites in orbit has disappeared from its predicted path. Lacrosse 2, whose transits have sometimes featured in our satellite predictions column, was cloaked in secrecy when it was launched atop a Titan 4 rocket in 1991. Amateur spacewatchers soon spotted it in orbit and have been keeping track of it ever since, deriving and publishing the orbital data that its US spymasters were withholding.
It is thought that, like four other Lacrosse craft, it was able to image targets on the ground by radar even in darkness and through clouds. Its demise, though, is probably not due to hostile action. Its predecessor, Lacrosse 1, was intentionally de-orbited in 1997 and it now seems that Lacrosse 2 has suffered the same fate, most likely being forced down over the South Pacific on or about 26 March. Remarkably, the first person to spot the craft in orbit 20 years ago, Russell Eberst of Edinburgh, was also the first to notice that it was missing.