The ultimate 4-wheel-drive: How ESA's keeping XMM-Newton alive after 20 years and beyond

You thought that yoghurt in the back of fridge was time-expired? Behold X-ray boffinry YEARS past its design-life

Space Extenders Sure - that telescope can be serviced by Space Shuttle astronauts. But how do you keep one running for years past expiration without a prodding by spacewalkers? Behold ESA's XMM-Newton....