- Scientists warn that space junk is threatening space exploration
- New mission aims to test debris removal ideas
- Saturn probe Cassini to make dramatic end to odyssey
- China planning ambitious lunar mission
(CNN)Space needs cleaning if costly catastrophic collisions are to be avoided, scientists warn.
Several litter-picking ideas to remove space junk from Earth orbit, including a net, a harpoon and a sail are due to be tested later in 2017.
Led by scientists from the Surrey Space Centre in the UK and funded by the European Commission, the RemoveDEBRIS project aims to tackle the growing problem of orbiting garbage that threatens satellites vital for the Internet, cell phones and navigation.
Space exploration 'at risk'
The group estimates that there is more than 7,000 tons of junk in circulation and NASA says more than 20,000 of the larger pieces are being tracked.
Debris ranges in size from large chunks of dead satellites and used rockets to flecks of paint. They are moving so fast -- faster than a bullet -- that even strikes from small fragments could be disastrous.
A chip in a window on the International Space Station (ISS) was recently photographed by visiting European Space Agency (ESA) astronaut Tim Peake. It is thought to have been caused by a paint flake or a miniscule metal fragment.
RemoveDEBRIS lead scientist Jason Forshaw told CNN: "We are reaching a situation where there's a huge amount of junk in space. People say space is big, but the reality is that the junk is contained in orbits that are commonly used."
He warned that missions costing hundreds of millions of dollars are at risk, with a real chance of satellites being "wiped out."
In partnership with Airbus and several others, the $15.7 million mission aims to release a small cube to test a variety of tools to grab the junk.
Once captured, debris be dragged back into the atmosphere where it would burn up. Another system uses a harpoon and what the team calls a "dragsail" that could be attached to larger pieces.
Cassini mission to end in fiery death
As one mission begins, another is coming to an end in 2017 as the Saturn probe Cassini is prepared for the final phase of its 20-year odyssey.
Launched in 1997, it has been sending data from the gas giant since 2004 but is now running low on fuel and when it runs out operators will not be able to control the spacecraft.
NASA and its mission partners from 17 countries want to prevent a possible collision and contamination of Saturn's moons Enceladus and Titan. They have chosen to send Cassini to a fiery death in Saturn's atmosphere.
But in what NASA is calling a "grand finale," Cassini will leap over Saturn's rings and make a "final series of daring dives between the planet and the inner edge of the rings."
Cassini's primary mission was to last four years but has been extended twice. NASA says on the project website that the spacecraft will collect "incredibly rich" information in its last act that the original planners might never have imagined.
Cassini will make detailed maps of Saturn's gravity and magnetic fields, sample icy ring particles and take ultra-close images of the planet's rings and clouds.
"What we learn from these activities will help to improve our understanding of how giant planets -- and families of planets everywhere -- form and evolve," NASA says on its website.
The final days of the Cassini mission may help with ongoing analysis of exoplanets -- planets beyond our solar system -- and two missions are planned to search for more of these alien worlds with launches in late 2017 or 2018.
In search of other worlds
ESA's CHEOPS space telescope will study in detail the bright stars already known to host planets with the aim of measuring the density of what it calls "super-Earths" and gas giant planets.
It is hoped that the mission will find likely targets for further study.
Thousands of children across Europe took part in a competition to submit drawings that will be sent into space on board the satellite. A total of 3,000 were selected and will be shrunk and engraved on two metal plaques.
In collaboration with SpaceX and other contractors, NASA is also planning an exoplanet mission.
TESS -- or Transiting Exoplanet Survey Satellite -- is designed to detect small planets that might be orbiting nearby stars.
NASA says that during its two-year mission it will monitor the light from more than 200,000 stars, searching for temporary dips in brightness as planets pass between Earth and the target star.
Scientists say the craft is expected to catalog more than 1,500 exoplanet candidates including 500 of a comparable size to the Earth.
NASA lists the working launch date as December 2017.
Focus on reusable spacecraft
This year may also see more testing in the space race between private companies SpaceX founded by Elon Musk, the product architect of Tesla; Blue Origin, set up by Amazon founder Jeff Bezos; and Virgin Galactic led by British entrepreneur Richard Branson.
All three are vying to make space travel cheaper, focusing on landing and reusing spacecraft.
SpaceX is developing the Dragon 2 spacecraft designed to carry cargo and ferry astronauts into space. It has been selected by NASA as one of the candidates to take them to the ISS. The company says on its website that manned flights will take place in "2-3 years."
NASA has also awarded a contract to Blue Origin to supply reusable launch vehicles -- joining five other companies developing new craft.
Blue Origin President Rob Meyerson told reporters at a space symposium in October that the company was "still on track for flying people -- our test astronauts -- by the end of 2017." Blue Origin told CNN it has nothing to add to that at this time.
Lockheed and NASA spent 2016 fitting avionics and propulsion tubing to their Orion spacecraft. And in the spring of 2017 they plan to turn on the computers as well as fit the heat shield and ESA's service module. An Orion manned flight planned for 2021 will take astronauts around the Moon.
China aims for the Moon first
China continues to push its own ambitious space program -- and may reach a major milestone in 2017.
China's National Space Administration has already said it will target a landing on the dark side of the Moon by 2018 and reach Mars by the end of 2020.
But deputy chief of the space program, Wu Yanhua, also confirmed last month that it will launch the Chang'e-5 lunar probe by the end of 2017, returning a Moon sample to Earth in the process.