DETROIT – Wednesday is a date I've had highlighted on my calendar for a very long time, as that's the day the European Space Agency's Rosetta spacecraft will deploy its lander, Philae, to the surface of Comet 67P / Churyumov-Gerasimenko.
I consider this mission to be one of the most important in human history, because not only is it theorized that comets bombarding Earth early in its history may have brought the water we have, but comets may have also brought the chemical building blocks that led to the development of life here.
Recommended Videos
The University of Michigan's Department of Atmospheric, Oceanic, and Space Science has a role in this mission (see the Local 4 story I did at bit.ly/1wlKOff ), and Dr. Michael Combi told me that a comet is as if somebody took a chunk of the stuff from the origin of our solar system and put it in a freezer for us to examine four-and-a-half billion years later.
Read: University of Michigan scientists involved with comet landing
He also told me that the comet is probably has the density of a shovel of snow, because Rosetta has already determined that the comet's density is half that of water (meaning that the water already detected on it is probably in the form of packed snow).
The bottom line is that it's possible Rosetta could answer important questions about our planet's origin.
The landing site, named Agilkia , is located on the smaller of the comet's two "lobes," with a backup site on the larger lobe. The sites were selected just six weeks after Rosetta arrived at the comet on August 6th, following its 10-year journey through the solar system.
By the way, Agilkia is named for Agilkia Island, an island on the Nile River in the south of Egypt. A complex of Ancient Egyptian buildings, including the famous Temple of Isis, was moved to Agilkia from the island of Philae when the latter was flooded during the building of the Aswan dams last century. So that explains how the lander and the landing site got their names. Since early August, the Rosetta mission has been conducting an unprecedented scientific analysis of the comet. But the main focus to date has been to survey 67P to prepare for the first ever attempt to soft-land on a comet. Agilkia was chosen unanimously over four other candidate sites as the primary landing site because the majority of terrain within a square kilometer area (a kilometer is two-thirds of one mile) has slopes of less than thirty degrees relative to the local vertical, and because there are relatively few large boulders. The area also receives sufficient daily illumination to recharge Philae's batteries and continue surface science operations beyond the initial sixty-four hour battery-powered phase.
Two robust landing scenarios have been identified, one for the primary site and one for a backup site. Both involve separation from Rosetta and the comet landing on Nov. 12.
For the primary landing scenario, Rosetta will release Philae at 3:34 AM EST at a distance of fourteen miles from the center of the comet, landing about seven hours later. The one-way signal travel time between Rosetta and Earth is 28 minutes 20 seconds, meaning that confirmation of the landing will arrive at Earth ground stations at around 11:00 AM EST.
If a decision is made to use the backup site, separation will occur at 8:04 AM EST, about eight miles from the center of the comet. Landing would occur about four hours later, with confirmation on Earth at around 12:30 PM EST.
And this mission gets even cooler: Rosetta and Philae will continue to study the comet and its environment using their many science instruments as they orbit the Sun together. So, the spacecraft will observe the development of the comet's tail as it approaches the sun, and the University of Michigan instrument aboard Rosetta will analyze the gases coming out of it. And don't forget that both Rosetta and Philae are armed with cameras, so we'll get the closest, most spectacular images of a comet ever!