Science: Best long reads of 2015 (part two)
Part two of our festive collection of Science and Environment reads. You can read part one here.
Enceladus: A second genesis of life? By Jonathan Amos.
The huge jets of water vapour that erupt from Saturn's moon Enceladus make this ice-crusted body unique in the Solar System. Before Nasa's Cassini probe studied it up close, the 500km-wide moon was just another small satellite of Saturn. But in the last decade, it has become one of the prime targets in the search for life beyond Earth.
Voyage to the North through ramparts of ice. By David Shukman
In the 19th Century, the Norwegian explorer Fridtjof Nansen came up with a then-controversial idea: use the natural mobility of ice to penetrate the "ramparts" of the Arctic and reach the North Pole.
Trouble in orbit: The growing problem of space junk. By Dr Hugh Lewis
Last year, the International Space Station had to move three times to avoid lethal chunks of space debris. The problem also threatens crucial and costly satellites in orbit. So what is the scale of the space junk problem, and what can we do about it?
We print people: The world of 3-D portraiture. By Jonathan Webb
Jonathan Webb delves into the world of 3-D portraiture, a burgeoning business whose aficionados include cosplayers, pet owners and even policemen. But what do people actually want with their mini-me's?
Lost in space? Nasa under pressure. By Pallab Ghosh
This year's flyby of Pluto brought back memories of Nasa at its best. But is the space agency's effort to explore the Solar System with robotic spacecraft in trouble?
The search for Britain's only native cicada. By Chris Baraniuk
The only cicada native to Britain hasn't been sighted in 15 years. But scientists now think they could be on the brink of re-discovering the rare insect, with the help of citizen scientists and a smartphone app.
How lucky Earth survived game of cosmic pinball. By Toby Macdonald
Rogue alien planets are forcing astronomers to rethink the birth of our Solar System. What's emerging is a tale of hellfire, chaos and planetary pinball - and it's a miracle our Earth survived.
Will animals of the future only be safe in captivity? By David Shukman
Look ahead towards the middle of the century and much-loved animals such as lemurs, rhinos and tigers could spend their existence in special zones guarded by fences and patrols and CCTV. Free, but only up to a point.
Life on the International Space Station. By various
There are currently seven billion people living on Earth. Although our lives differ in countless ways - almost all of us share some common experiences. But there are six people out of seven billion whose daily experience sets them apart. They are 400km above our heads on the International Space Station.
Malawi's battle to hold on to its forests. By Roger Harrabin
Malawi's own greenhouse gas emissions from fossil fuels are minuscule. But the nation has one of the highest deforestation rates in the world as people desperate for fuelwood hack into the once-rich forests.