The X-ray Multi-Mirror satellite will be the most powerful X-ray telescope ever placed in orbit: It will have an unprecedented sensitivity and scientists are sure the mission will help solve many cosmic mysteries. While the huge satellite resembles NASA's Chandra from the outside and the general optical concept, XMM is not a competing but a complementary mission, concentrating on spectroscopy and gathering as many X-ray photons as possible. This largest science satellite ever built in Europe carries 3 very advanced X-ray telescopes. They each contain 58 concentric mirrors, delicately nested to offer the largest collecting area possible to catch the elusive X-rays.

These Mirror Modules will allow XMM to detect millions of sources, far greater than any previous X-ray mission. And the satellite's highly eccentric orbit, travelling out to nearly one third of the distance to the Moon, will allow astronomers to make very long and uninterrupted observations. On its 48-hour orbit, it rises to nearly one third of the distance to the Moon. At this apogee 114 000 km away from Earth, the satellite travels slowly. But at its perigee it passes 7 000 km above our heads and nine times faster!

NASA will declare a "minimum mission success" when the Discovery astronauts manage to leave the space telescope behind with five working gyros, four of which must be newly installed (at the moment, there are only two old ones still working onboard). A "full success" would have been reached with all 6 gyros replaced and working, plus the exchange of a Fine Guidance Sensor, the onboard computer and 6 Voltage/Temperature Kits (to better protect the satellite's batteries). During their four EVAs, the astronauts also plan to replace the last tape recorder with a solid-state memory, to replace a failed S band transmitter and to carry on with the repaits to Hubble's thermal blankets started in 1997.

Disaster could have struck at any time during the 12 minutes between the switching off of the MPL's transmitter and touchdown, during contact with the never before explored surface of Mars' south polar region, or in the minutes afterwards. One persistent speculation is that the cruise stage didn't separate properly from the lander, which would have doomed the microprobes as well, other ideas involve just an unlucky landing, e.g. on a rock or in a crack of the surface. Other than that only multiple failures of onboard systems could explain the silence.

While the Mars Surveyor program as well as NASA's current 'faster cheaper better' approach to science mission is being reviewed thoroughly both inside NASA and among scientists and space buffs worldwide, the investigation into the MPL loss will soon begin. Lacking any telemetry the main source of information will be scores of photographs documenting the construction of the lander - and perhaps telling images from the MGS' high resolution camera. If a nominal touchdown has occured, at least the parachute, the heat shield and effects from the braking rockets should be visible - and if the cruise stage didn't separate, there should be a new impact crater in a different region...

Using computer simulations, the researchers tested how a massive planet the size of Jupiter would interact with a massive disk, 10 times larger than the disk thought to have given rise to our own solar system. They found the extra gravitational force from the planet would cause parts of the disk to collapse and fragment into other planets. The resulting planets would also be gigantic, but would be mostly gaseous rather than solid like that of Earth. And apparently there is an upper limit to the amount by which planets can grow. If the planets formed close together, the planetary system would become violently unstable - some planets would be ejected from the system and the remaining ones would be left with eccentric orbits.