My goal is to make a solo winter 'round-trip' crossing of the Vatnajokull Icecap, Iceland. I will travel on ski, pulling a sledge loaded wth food and equipment. I'll begin on the West side, ascend to the 1,500m (roughly one-mile)-high ice plateau, cross the plateau to the East side, descend, and then turn around to retrace my steps and return to my starting point, a round-trip journey of roughly 200 miles (c.320km).Temperatures hover around -20C (-4F) on the ice cap plateau, and can drop radically with windchill. Rising temperatures are not what I want, because warmer means wetter, and wet & cold are a lethal combination. In winter, I'll have a few hours of daylight each day, but a lot of my work is done in the gloom of half- or quarter-light. From my previous expeditions I know it's a challenging place to survive, let alone try to cross and return. It's a challenge I can't resist.

Iceland well North on our planet.

Throughout the trek I will be completely self-supported and self-reliant, although I do carry a satellite phone for communication. I will take a large food reserve in order to be able to wait out long storms, which are common on the icecap in winter. It is difficult to estimate the trek duration: on a good day, I may make 10 miles (16km). On a poor day, with complications due to crevasses for instance, I may make only a mile or two, or even be forced to backtrack. The ice cap weather is particularly violent in winter, and there are only a few hours of full daylight per day. Prolonged storms can pin me down for a week or more at a time. I carry 40+ days of food and stove fuel for my cooker.

Iceland is a storm-swept country just crossed by the Arctic Circle.

A month-long trek through this dark, frozen and gale-swept environment is a serious challenge, particularly because I am alone on the ice. There is no-one to help with cooking, setting up the tent, navigation... I must do everything, and I cannot afford to make any mistakes. Such work is challenging and exhausting. My expeditions to Iceland so far have given me experience that cannot be bought, or forgotten.

Vatnajokull is one of the largest ice caps outside the Polar regions. Iceland has a maritime climate: cold and damp. The 160km (100-mi) -wide ice cap is an enormous ice sheet of over 8,100 square km (c. 3,100 square miles). The arrow at lower right indicates the view for the image below, generated with the software package 'Flying Over Iceland' and modified by me in several ways.

Italian mountain guide Paolo Mantovani crossed the ice cap alone in winter, from North to South, in early 2002, so a winter solo ski crossing has technically been completed, and I congratulate Mr. Mantovani on his achievement. My 'return-trip' crossing is about four times the distance of the North-South crossing. Even if someone were to complete the goal I've set for myself before I make my next attempt, it would remain a fascinating voyage, one I am still very excited about. This year high-school age students around the globe will follow my expedition, being encouraged to think about the parallels of exploration in harsh environments on Earth and on Mars. I'll be working with the Mars Society, the Earth and Space Foundation and a number of other exploration/education groups to make this aspect of the expedition a success. My goal is to get students to think about the exploration of Mars, about human adaptation to extraterrestrial environments, the subject of a book I'm working on with my colleage, E.T. Davies. For all of these reasons, this year's expedition will be particularly exciting. Every day I cross off another day on the calendar and savor the 'pre-expedition euphoria'. I could not survive without an expedition plan 'in the works'.

I'll be making my fourth attempt cross the ice cap the long way, from West to East (left to right on this map), and then return for a roughly 320km (200 mile) round-trip course, on foot, alone in the winter.