Initially disregarded as merely "rock and ice" by Subcommander T'Pol, upon further analysis it was discovered to contain large quantities of eisillium located under a 20 meter thick layer of magnesite. With eisilium being extremely rare, Captain Archer suggested obtaining a sample with the transporter. With the layer located out of transporter range, Lieutenant Reed suggested making use of the portable drilling rig with Ensign Mayweather's assistance.
During the "comet walk," the drilling team experienced several setbacks including a broken drill bit due to a layer of magnesite, a rotational axis shift resulting in the dawn approaching sooner than expected causing the temperature to increase by several hundred degrees, and the shuttlepod falling into a chasm due to melting ice. Enterprise attempted to use the grappler and pull the shuttlepod to safety, however a secure hold could not be obtained. The drilling team was eventually rescued by the Vulcan ship Ti'Mur. (ENT: "Breaking the Ice")
In reality, optimistic estimates place the diameter of the nucleus of the comet Hale-Bopp at 60 +/- 20 km, thereby putting it very close to Archer's Comet.