Boeing is developing a commercial variant of the Delta-4 Expendable Launch Vehicle designed to lift medium and heavy military satellites. (Delta-4 was developed with government funds, as was the competing Atlas-5.) The commercial Delta-4-medium-plus may use two or four strap-on boosters. It can lift 4,853-6,668kg into geostationary transfer orbits, or 7,850-10,300kg into low Earth orbit. The problem is that after two failed launches of the Delta-3, Boeing is finding it hard to convince commercial customers to risk expensive satellites on the untried booster. One option (and an expensive one) is to conduct a demonstration launch with a dummy satellite. That would produce no revenue for the company, but would (if it works) convince customers that the Delta series is reliable. Such demonstration launches were once almost unheard of, but a series of recent failures by numerous types of boosters has made such launches more common. --Stephen V Cole