Tweeting From the Final Frontiers

Once upon a time, astronauts who flew to space and mountain climbers who scaled peaks returned home with tales of their adventures. Now, social media has vanquished the anxious wait for story time and given those left at home a chance to see the sights for themselves.

In 2013, Canadian astronaut Chris Hadfield captured the world's imagination by singing, celebrating holidays and snapping photos from the International Space Station. Last year, his American and German colleagues Reid Wiseman and Alexander Gerst did the same, sharing poetic images and videos of Earth on Twitter and Vine as they spent time on the ISS. The material the three collected while weightless became the stuff of time lapses and books that further engaged the public.

Farther out in space, the Rosetta mission in November became the first to accomplish the soft landing of a probe onto the surface of a comet. The European Space Agency took to Twitter to personify both the Rosetta spacecraft and its lander, Philae—both send out messages in the first person as their mission unfolds.

Meanwhile back on Earth, Tommy Caldwell and Kevin Jorgeson are posting updates on Twitter, Instagram and Facebook as they attempt to complete the Dawn Wall route on El Capitan, a steep slab of exposed granite at Yosemite National Park in California. Caldwell's wife, Rebecca, is also blogging from the ground. If successful, the duo will become the first to "free climb" the Dawn Wall, i.e. climbing it without help, with only a rope attached in case of a fall.

"Should they be successful in free climbing the Dawn Wall, it will be one of the most significant climbing achievements of all time," Andrew Bisharat wrote on National Geographic's adventure blog, Beyond the Edge. Tom Evans, who was the first to climb El Capitan nearly half a century ago and now writes a blog called "El Cap Reports," told The New York Times that "if they get it completed, it will be the hardest completed rock climb in the world.… This will be the climb of the first half of the 21st century."

The climb, which began on December 27, is divided into 32 sections, or pitches, some more arduous than others. In between climbs, on which Jorgeson and Caldwell embark primarily in late afternoon and evening, they are "hanging" out at camp in tents suspended off the side of Dawn Wall—eating, sleeping, and communicating with family, friends and adventurers by proxy. This past Friday, Jorgeson even hosted a live Q&A via Twitter from 1,200 feet up El Capitan.

Here's a smattering of updates from the pair's climb, which they could complete by Friday or Saturday if all goes well. For the full coverage so far, and to follow the rest of the journey, see Caldwell and Jorgeson's tweets, their Instagram accounts, and their Facebook pages.