A huge space rock 1.7 miles across is set to make its closest flypass of the Earth later this evening.
The asteroid, named 1998 QE2, will pass around 3.6 million miles away from the earth - around 15 times the distance to our moon.
Though a considerable distance from the earth the proximity of the flypass will allow scientists, using the latest radar technology, to examine the rock.
Nasa said it was an opportunity to get "best look at this asteroid ever."
Private firms are keen to examine the possibility of mining such rocks which are thought to be rich in precious metals.
Using powerful telescopes scientists should be able to observe the asteroid's own moon and examine the rock's surface features. At 3.6 million miles away the 1998 QE2 is no risk to earth.
Had it been on a direct collision course, however, it would have disastrous consequences for the planet, flattening everything within 200 miles of impact and potentially sending such huge amounts of dust into the atmosphere that it would block out of the sun.
The approaching asteroid, which has its own moon in tow, is expected to be closest to the Earth at 9.59pm, UK time.
The flypass comes just three months after Earth’s 'near-miss' with the 150ft-wide asteroid 2012 DA14.
That particular asteroid came around 17,200 miles from the planet - placing it within the orbits of more than 100 telecommunication and weather satellites.
Even from 3.6 million miles away scientists expect to be able to identify features on Asteroid 1998 QE2 as small as 12ft across.