What is Nasa’s Osiris-Rex capsule and when will it land on Earth?

A mosaic of the asteroid Bennu, a sample of whose dust is expected be on Earth this Sunday  (Nasa/Goddard/University of Arizona)
A mosaic of the asteroid Bennu, a sample of whose dust is expected be on Earth this Sunday (Nasa/Goddard/University of Arizona)

Nasa’s first-ever asteroid sample-return mission is about to land on Earth.

In October 2020, the $1 billion Osiris-Rex mission successfully collected a sample from the asteroid Bennu, which will now be landed on Earth by the spacecraft's descending capsule.

Here is what we know about the Nasa mission.

What is Nasa’s Osiris-Rex mission?

Osiris-Rex (which stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) is the first US mission to collect a sample from Bennu, a tiny, near-Earth asteroid that orbits the planet every six years or so.

The sample capsule will be released by the Osiris-Rex spacecraft and is intended to land safely in the Utah desert.

Nasa believes that about 700 million to 2 billion years ago, Bennu probably split off from a much larger carbon-rich asteroid. It is likely to have formed in the Main Asteroid Belt, which is the region between Mars and Jupiter, and has subsequently moved much nearer to Earth.

Due to the age of its constituent parts, Bennu may include organic compounds that are related to those that may have contributed to the emergence of life on Earth. The rocks and dust from the surface of Bennu, which were recovered in October 2020, will provide scientists with a glimpse into the period of time when the Sun and planets were forming, some 4.5 billion years ago.

As tall as the Empire State Building, the likelihood of Bennu colliding with Earth during one of its close encounters with the planet in the late 22nd century is estimated by scientists to be 1 in 2,700 but it is most likely to hit Venus.

When will the Osiris-Rex capsule enter Earth’s atmosphere?

On May 10, 2021, Osiris-Rex left the Bennu vicinity to head towards Earth, where its capsule is expected to land on September 24 with the asteroid sample. You can watch the landing, which is expected at about 3.55pm BST, live on YouTube.

Bennu was first detected on September 11, 1999, during a survey by astronomers at the Lincoln Laboratory Near Earth Research near Socorro, New Mexico. Its name came from a third-grader called Michael Puzio who won the naming contest.

What’s next for Nasa?

A news conference for the Osiris-Rex asteroid sample reveal is scheduled by Nasa for October 11.

While investigations into the Bennu sample are underway on Earth, the spacecraft will start a new mission called Osiris-Apophis Explorer (Osiris-Apex) in which it will set off for an encounter with the asteroid Apophis in 2029.