Nasa is set to make a major announcement about its first mission “to touch the sun”.

The agency wants to send a spacecraft closer to the sun than ever before, where it will face extreme temperatures and radiation levels.

It will speak about Solar Probe Plus at an event on Wednesday, which will be livestreamed on Nasa Television and the agency’s website from 4pm BST.

Nasa unveils space tourism posters Show all 6 1 /6 Nasa unveils space tourism posters Nasa unveils space tourism posters Nasa space tourism posters Nasa's canny decision to commission sumptuous vintage-inspired posters by Seattle design firm Invisible Creature has firmly placed space travel back where it belongs: in the imagination of travellers Nasa Nasa unveils space tourism posters Nasa space tourism posters It is particularly fitting that the Nasa commission went to Don and Ryan Clark, who have been running Invisible Creature since 2006, undertaking projects for the likes of Nike and Target Nasa Nasa unveils space tourism posters Nasa space tourism posters "We were ecstatic, just because our grandfather was an illustrator at Nasa for 30 years," says Clark Nasa Nasa unveils space tourism posters Nasa space tourism posters The artwork harks back to the Jet Age-era posters commissioned by Howard Hughes' Trans World Airlines and its rival United in the 1950s and 1960s, when the work of David Klein (for TWA) and Stan Galli (for United) glamorised and essentially branded this new age of air travel Nasa Nasa unveils space tourism posters Nasa space tourism posters It doesn't matter that Nasa has no plans for a "Grand Tour" of Jupiter, Saturn, Neptune and Uranus Nasa Nasa unveils space tourism posters Nasa space tourism posters If global travel is for daydreamers, going beyond the atmosphere is for true space cadets Nasa

The spacecraft, which is set to take off in the summer of 2018, will be tasked with collecting data about the mechanisms that heat the corona, the outermost part of the sun's atmosphere.

For reasons currently unknown, the corona is hundreds of times hotter than the sun’s surface, with temperatures at 500,000 degrees Celsius or higher.

It’s also behind the solar wind, a constant stream of charged particles that can impact life on Earth.

“Placed in orbit within four million miles of the sun’s surface, and facing heat and radiation unlike any spacecraft in history, the spacecraft will explore the sun’s outer atmosphere and make critical observations that will answer decades-old questions about the physics of how stars work,” said Nasa.

Nasa release year-long time-lapse of the Sun

“The resulting data will improve forecasts of major space weather events that impact life on Earth, as well as satellites and astronauts in space.”

The spacecraft will have to withstand temperatures of up to 1,400 degrees Celsius, which it plans to do with the help of an 11.5cm-thick carbon composite shield.