They have no rudder with which to change course; no propellant to carry them past danger.
This causes the propellant to vaporize, leaving very finely subdivided liquid or solid particles dispersed in the vaporized propellant.
While consumer spending has provided a major propellant to the economy in recent years, troubling signs that the consumer may finally be dropping rather than shopping have cropped up.
On the mission's eighth day, after all of the cargo has been unloaded to the station, the shuttle will use its leftover propellant to raise the station to a higher orbit.
In testimony prepared for Wednesday's hearing, Mr. O'Keefe said the space station "is stable and has sufficient propellant to maintain its orbit for at least a year without support" from the shuttles.
Your PC can help design drugs against AIDS, model the future climate of the planet, search for new prime numbers or simulate micro-devices for handling satellite propellant, to cite just a few examples.
But another reason was that it performed so well and remained so healthy that it was left with enough unused propellant to enable it to maneuver through 64 additional orbits, after having already completed 75 in its first four years.
Energetic plasticizers are also added to the propellant to improve its performance.
