Samples from astroid will help scientists learn more about Earth

On Sept. 25, a space capsule entered the atmosphere and parachuted to a soft landing in the Utah desert.

It brought with it a scientifically priceless cargo—samples of material from the surface of an asteroid. We hope this material from a distant astronomical body will provide important information about the formation of the Earth, and possibly how life got started.

On Sept. 8, 2016, an Atlas V rocket lifted off from Cape Canaveral, carrying a two-tonne spacecraft called OSIRIS-REX. This meticulously constructed acronym is short for "Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer".

Its destination was the asteroid Bennu. This object is comparatively small by asteroid standards, having a diameter of roughly 260 metres and weighing in at about 78 million tonnes. This asteroid was chosen because it passes close to the Earth, making it easier for us to get to compare it with its brethren orbiting the Sun between Mars and Jupiter.

In addition, there is a chance this asteroid could hit the Earth at some time in the future. So this was a chance to see what sort of body it is, in time to plan our countermeasures as and when the need arises.

The launch rocket did not have the power needed to put the spacecraft on a direct path to Bennu, so on Sept. 22, 2017, it did an Earth flyby to use our planet's gravity to change its course and speed. It arrived at Bennu in October 2020, and started to survey the asteroid's surface and to do a range of scientific studies.

On Oct. 20, 2017, it did a “touch and go” visit to Bennu's surface, grabbing a sample of the asteroid's material. Being so small, Bennu's gravity is so weak the spacecraft could be allowed to fall slowly to the surface, grab the sample and with a small blast from its thrusters, bounce back into space.

The spacecraft continued to survey the asteroid until April 7, 2021 and on May 10, it fired its engines to start its journey back to Earth. The precious sample of asteroid material was placed in a tightly sealed container and put into a capsule for dropping as the spacecraft flew past the Earth, en route to its next destination, Apophis, another potentially Earth-threatening asteroid, and therefore relatively easy to get to. With a diameter of about 350 metres, Apophis is a bit larger than Bennu.

We are very interested in asteroids because they are as close to being original samples of the construction material used to build the Solar System as we are likely to get.

Here on Earth, the weather, plate tectonics and our activities have modified, recycled and processed material to the point where there is nothing left of the primordial material that formed our world.

The rock samples brought back from the Moon by the Apollo astronauts and some robotic space vehicles are certainly less processed, but are they original? Our current idea is the Moon was formed when an object the size of Mars collided with the body that would become the Earth. As the wreckage coagulated into the Earth and Moon, it was almost certainly changed by the experience.

Apart from letting us know the ingredients from which the planets formed, and where our water came from and so on, the big question for us is does this raw material contain the chemical progenitors of life? If present, are they the basic chemical ingredients, or will they be more developed ones, like amino acids.

Canada contributed instrumentation for this mission, so we get some of the sample. A large portion of the material is going to be stored for future scientists to work on.

Another important result of this mission is hopefully that we can avoid getting a much bigger sample of this asteroid, delivered at high speed, free of charge, some time in the future.

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• Saturn rises in the southeast just after sunset, with Jupiter following about an hour later. Venus rises around 3 a.m. Mercury lies low in the dawn glow.

• The Moon will reach last quarter on the Oct.4.

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory near Penticton.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.