Orbital Sciences remained mum on a replacement engine for its ISS cargo carrier last week, but Russian news outlets have identified the new kerosene-fueled RD-193 developed by NPO Energomash as the chosen one.

The lander lost contact with ground controllers early this morning, but not before they sent commands to rotate the probe's solar panels to glean additional sunlight.

With the clock ticking, mission managers weigh a plan to shift Philae's position and gain more exposure to the sun.

"Figuring out where high energy neutrinos come from is one of the biggest problems in astrophysics today," said Yang Bai, University of Wisconsin at Madison physicist.

Rosetta is the first mission designed to orbit and land on a comet. The €1.4 billion exploration campaign, the first to undertake a lengthy exploration of a comet at close quarters, builds on the first fly-bys of comets in the 1980s led by NASA, ESA, Russia and Japan.

While the SpaceShipTwo crash investigation continues, the full impact on the vehicle’s design and operations, as well as the effect on Virgin Galactic’s schedule, remains unclear.