As she skis across Antarctica, Felicity Aston is taking on dangers including crevasses, storms and frostbite. Her biggest challenge has been adapting to solitude in the seemingly endless expanses of white.

For more than three weeks, she has been skiing toward the South Pole, pulling two sledges packed with supplies. Aston, 34, is attempting to become the first woman to cross Antarctica alone, and has covered about a third of the journey of more than 1,000 miles.

The British adventurer expects to reach the South Pole this week, then pick up more supplies and head out again for the other side of the frozen continent. She said the emotional toll has been much greater than expected.

"When that plane disappeared and left me on the wrong side of Antarctica all by myself with two little sledges, it really hit me that I'm completely responsible for myself," she said by satellite phone. "It's just you. You have to sort out your problems, and that makes you feel very vulnerable."

When alone in Antarctica, little problems can easily become big problems.

The three cigarette lighters she brought to start her camp stove suddenly stopped producing a flame in the cold, leaving her with only matches for a time, though she finally managed to get the lighters working again, intermittently.

And her breath freezes and forms icicles on her mask as she skis in temperatures of minus-25 and below.

Each day, she pitches a tent, cooks a freeze-dried meal on her stove and posts on Twitter.

"Ice coating my fur hood and icicles hanging off my mask and goggles made me look like a real polar explorer today," she posted Saturday.

Sometimes, she raves about the beauty of the landscape. Other times, she said she feels tired, bitterly cold or even a bit overwhelmed.

Aston worked as a meteorologist in Antarctica and is a veteran adventurer who has led team expeditions in the Antarctic, Arctic and Greenland. She said she decided to attempt her first solo crossing to test her personal limits and also because she was curious about being on her own.

Aston set out Nov. 25 from the Ross Ice Shelf, climbing a glacier dotted with crevasses in the Transantarctic Mountains before emerging onto the continent's vast central plateau. Some days, Aston has skied through drifting snow. Others, she has soldiered through sastrugi, waves of ice sculpted by fierce winds.

Once she reaches the South Pole, she will make a sharp pivot and head toward Hercules Inlet, where she hopes to finish her trip in late January.

Aston this month said that when she unpacks her tent after a hard day, "that's when the demon voices come out, and you hear little voices in your head going, 'What are you doing?' and, you know, 'You could be at home nice and warm right now.'

"But you do have to try and push those to one side. Once I'm out there and skiing, then I know exactly why I'm here. Today, it felt like I was walking along the top of clouds."