All About Space - UK (2020-02)

OSIRIS-REx

NASA’s asteroid explorer has been at Bennu for over a year

now, but the best part is yet to come

SIRIS-RExisthethirdpartofNASA’s

NewFrontiersProgram,succeeding

thelikesofNewHorizonsandJuno.

Allthreearecompletelyreshapingour

understandingoftheSolarSystem,andOSIRIS-REx

isdoingsoattheasteroid 101955 Bennu.

TheOrigins,SpectralInterpretation,Resource

Identification,Security,RegolithExplorer(OSIRIS-

REx)spacecraftwaslaunchedwitha gameplan

tobreakrecordsanddosomethingthathasn’t

beendonesincetheApolloera.“It’sa missionto

reachouttoa near-EarthasteroidnamedBennu

andsurveythatobjectingreatdetail,ultimately

selectinga singlelocationontheasteroidsurface

tosendthespacecraftdownfora briefcontactto

collectmaterialthatwewillreturntoEarthfor

analysisinourlaboratories,”explainsLauretta.

Whenthespacecraftsendsitsreturncapsule

toEarthfromBennuinSeptember2023,carrying

attheveryleast 60 grams(2.1ounces)ofasteroid

regolith,itwilldelivera samplefromspaceina

quantitythathasn’tbeenseensincetheApollo

astronautsreturnedlunarsamplesinthe1960sand

1970s.ButwhatmakesBennusospecial?

FirstisthatBennuisa near-Earthasteroid,

andbeingincloseproximitytoEarthmeansthe

spacecraftdoesn’thavetojourneytotheoutskirtsof

theSolarSystemtosampleit.Secondly,theasteroid

issmallenough– witha diameterofroughly 500

metres(1,600feet)– androtatesslowlyenoughthat

itenablesOSIRIS-RExtoenteritsorbitandconduct

close-upobservationswithoutorbitalcomplications.

Thirdly,Bennuisa rareB-typecarbon-richasteroid

thatastronomersbelievecouldholdcluesabout

theSolarSystem’sinception.Bennucanbethought

ofasa frozentimecapsule,leftoverfromthe

formationoftheplanets.

“WechoseBennuspecificallybecausewe

knewa lotaboutitandintriguinghintsaboutits

composition,”saysLaurette.“WethinkBennumay

havewaterintheformofclaymineralsandorganic

moleculesthatwethinkmayhaverepresentedthe

seedsfortheoriginoflifeonEarth.”

O

4.5 billion years ago, asteroids, comets and other

pieces of space rock began to accumulate until

they formed the planets and dwarf planets that are

seen today. In the process, some of these planets

acquired liquid water on the surface, such as Earth

and Mars, and Earth was even blessed with organic

compounds that provided the building blocks for

human life. Scientists believe that asteroids such as

Bennu are the key to understanding how chemistry

created biology. “OSIRIS-REx really seeks to answer

some of the most fundamental questions that we

ask ourselves,” says Laurette. “It’s a great example

of what humanity can accomplish when a talented

group of dedicated people put their minds on a

single objective.”

This sample-return mission has another goal

in understanding the current nature of near-Earth

asteroids. When it comes to around-the-clock

asteroid observations, modern techniques have

brought to light just how hazardous these objects

can be. By scrutinising Bennu, the mission could

provide vigilant astronomers with important

information about a future Earth-bound asteroid.

Not only that, but asteroids could soon become

utilised in space mining. Companies could soon

be sending mining missions to asteroids to extract

their rare resources, and OSIRIS-REx can provide

a more complete understanding of what resources

might be hidden within.

OSIRIS-REx arrived at Bennu on 3 December

2018, beginning an in-depth survey of the entire

surface, mapping from pole to pole. While doing

so it has been slowly decreasing the altitude of

its orbit, and it will continue until it hovers just

240 metres (800 feet) over the asteroid’s surface.

In July 2020 OSIRIS-REx will perform NASA’s

first-ever robotic sample collection of a celestial

object using the Touch-And-Go (TAG) sampling

manoeuvre. After collecting an adequate sample the

spacecraft will depart from Bennu in March 2021,

where it will cruise back to Earth and drop off an

uncontaminated sample – fresh from the vacuum of

space – in the Utah Desert in September 2023.

Mission type

Sample return

Operator

NASA

Launch date

8 September 2016

Target

101955 Bennu

Arrival at target

3 December 2018

Primary objective

Survey and collect a sample
from a carbon-rich
near-Earth asteroid
Status
Operational

Professor

Dante Lauretta

Principal investigator of

the OSIRIS-REx mission

Lauretta is a professor of

planetary science

and cosmochemistry at

the University of Arizona’s

Lunar and Planetary

Laboratory in Tucson,

Arizona. He specialises

in near-Earth asteroid

formation and evolution.

© Symeon Platts/UA