A former U.S. astronaut concerned about the danger posed to Earth by asteroids is set to meet with the United Nations this week to discuss the risk.

Russell "Rusty" Schweickart, once an astronaut with the National Aeronautics and Space Administration (NASA), is set to talk to the UN's Committee on Peaceful Uses of Outer Space about progress toward creating global plan to deal with the asteroid threat.

Scientists believe an asteroid or meteor that struck Earth millions of years ago was responsible for the extinction of dinosaurs.

Astronomers are currently tracking the 140-metre long Apophis asteroid that is expected to approach Earth, and has a one in 45,000 chance of hitting it on April 13, 2036.

Speaking at the American Association for the Advancement of Science meeting held in San Francisco over the weekend, Schweickart issued a call to action.

"It's not just Apophis we're looking at. Every country is at risk. We need a set of general principles to deal with this issue," he said on Saturday.

Schweickart — chairman of the B612 Foundation that aims to develop a controlled way to change an asteroid's orbit by 2015 — said he wants the UN to take charge of evaluating the threat asteroids pose and how to deal with them.

Most potential threats not yet detected

NASA's Spaceguard or near-Earth object detection program has been seeking out and mapping an estimated 1,100 near-Earth asteroids (NEAs) in 1998 but has so far found around 670 of them. The program's goal is to map 90 per cent of so-called "planet-killer" NEAs larger than a kilometre in diameter by 2008.

But Schweickart, members of the Association of Space Explorers — the international professional group of astronauts and cosmonauts Schweickart founded — and other scientists and engineers are also concerned about an estimated 200,000 asteroids that are between 100 metres and one kilometre across, few of which have been spotted to date.

The plan that the B612 Foundation favours involves putting a plasma engine powered by a nuclear reactor on a potentially dangerous asteroid and using the thrust to change its orbit enough to avoid striking Earth.

Schweickart, B612 Foundation and UN spokespeople could not be reached for comment.

Schweickart was the pilot for the first manned flight of NASA's lunar module on the Apollo 9 mission in 1969, and in a 46-minute spacewalk tested the life-support backpack later used by astronauts on the moon.