Artist's idea of the OSIRIS REx spacecraft amassing materials from Bennu. NASA/Goddard Area Flight Middle

Aid confirmed clearly on the faces of the crew of NASA scientists and engineers as they had been advised: “Landing is full”. Then applause just a few seconds later for “again away burn full”. Essentially the most hazardous a part of the mission was over – and seemingly profitable, though we should look ahead to just a few extra days to listen to the size of the success.

OSIRIS-REx (for Origins, Spectral Interpretation, Useful resource Identification, Safety, Regolith Explorer)) was launched in September 2016, arriving at its goal asteroid 101955 Bennu in December 2018. The aim of the mission was to characterise the asteroid, then convey a few of it again for examine on Earth.

The spacecraft spent two years circling Bennu, making detailed maps of its floor, studying as a lot as attainable concerning the asteroid earlier than the following part of the mission: searching for someplace secure to land. Or, slightly, to not land, however to make a really fast “touch-and-go” go to to the floor – the place it could accumulate fragments of fabric to return to Earth. It was completion of the touch-and-go manoeuvre that prompted the clapping and cheering in mission management.

Why Bennu? And why the aid? In any case, this isn’t the primary asteroid {that a} spacecraft has visited – and it isn’t the primary small physique that has been landed on. That file is held by the NEAR spacecraft that made a managed crash-landing on Asteroid 433 Eros in 2001. And I nonetheless bear in mind the emotion within the management room when Philae landed on comet 67P/Churyumov-Gerasimenko in 2014.

The aid was as a result of Bennu is small – solely about 500 metres throughout – a proven fact that was recognized when it was chosen as a goal. However it’s oddly formed and lively – two issues that weren’t recognized. It appears to be like a bit like an old school spinning prime, or a tough diamond, pointed on the prime and backside and fatter within the center. As a result of it’s so small it was assumed that Bennu could be quiescent – it wouldn’t, as an illustration, be behaving like a comet and ejecting bursts of fuel and rocks.

However as a result of nothing within the photo voltaic system is easy, when OSIRIS-Rex bought near Bennu, it discovered that the asteroid was throwing small quantities of fabric from its floor. The particles had been lower than a centimetre throughout, and most of them landed again on the asteroid – typically nearer to the equator than the poles, which modified its form over time.

Picture of Bennu taken by OSIRIS-REx in 2018.

NASA/Goddard/College of Arizona

One of many penalties of the exercise – defined by adjustments in temperature fracturing bigger boulders and breaking apart the rocks – is that the floor of Bennu is totally lined in rubble, far more than had been anticipated. This made choosing a website for pattern assortment tougher.

Secrets and techniques of the photo voltaic system

Bennu is a Close to Earth Asteroid – it has a one-in-2700 likelihood of colliding with the Earth in about 170 years’ time. Additionally it is believed to be wealthy in the kind of natural compounds which may have seeded the Earth to allow life to come up.

One other shocking discover that got here from the mapping marketing campaign was that Bennu was not solely wealthy in clay minerals, however that veins of carbonate had been current. Clay and carbonates require water – plenty of it – so these minerals should have fashioned when Bennu was half of a bigger asteroid. There isn’t a working water there now – however there is perhaps small pockets of ice under the floor. Whereas this ice is not going to be collected by OSIRIS_Rex, the consequences of water must be seen within the materials it’s gathered.

Learning these supplies will assist us perceive the primitive mud from which the photo voltaic system grew, and the vary of natural compounds current. It would additionally inform us the bodily properties of one thing which may hit the Earth, doubtlessly serving to us cease it.

It was at all times going to be difficult to gather materials from the floor – any try and land could be unlikely to succeed, as a result of the low gravitational pull of Bennu wouldn’t seize onto a lander and maintain it in place. A lander would bounce off, again into house. For this reason NASA used the touch-and-go method – the spacecraft approached the asteroid very slowly, hovering solely a metre or so from its floor, whereas an arm was prolonged to the touch the floor to gather a pattern.

It did this by blowing a jet of nitrogen fuel onto the floor, which was sufficiently highly effective to throw materials into the gathering cannister. The gradual method to the floor took a number of nail-biting hours, whereas the gathering operation took a matter of seconds. Assortment over, and the spacecraft backed away – therefore the aid at mission management on the “again away, burn full” message, exhibiting that OSIRIS-Rex was transferring away from the floor.

We don’t but understand how a lot materials was blown into the cannister – and we gained’t know till it arrives again on Earth in September 2023. It is perhaps 60 grams – which is the goal – or it is perhaps as a lot as a kilogram. An try will probably be made later this week to see how the second of inertia of the spacecraft – its uniform movement in a straight line – has modified, which ought to give a primary approximation of the quantity collected.

When the pattern comes again to Earth, it will likely be analysed by a world crew of scientists who will measure all features of the fabric’s composition and construction, particularly the natural and water contents of the soil.

That is after we’ll get some solutions, which can inform us about our personal origins as a lot as concerning the origin of asteroid Bennu.

I dedicate this piece to the reminiscence of Professor Michael J. Drake, a pal and colleague. He was the unique proposer of the mission that ultimately grew to become OSIRIS-REx, however died in September 2011, earlier than he might see the mission launched.

Monica Grady is Professor of Planetary and Area Sciences on the Open College. She receives funding from the STFC and the UK Area Company. She is a Senior Analysis Fellow on the Pure Historical past Museum and Chancellor of Liverpool Hope College. She could be adopted on twitter @MonicaGrady