Within a week we had headlines made by two NASA missions visiting asteroids up close (and of course who could forget the amazing smash-visit of the DART spacecraft to asteroid moonlet Dimorphos — and the fact that the impact significantly altered the moonlet’s orbit around its parent asteroid!). But about a week ago, Earth was visited briefly by the Lucy spacecraft — exactly one year after its spectacular launch from Kennedy Space Center.

Lucy is on its way to visit the Trojan asteroids – a group of space rocks sharing an orbit with Jupiter. One batch is ahead of the giant gas planet, and another follows behind. Both sets are in a stable orbit that keeps them from being grabbed by Jupiter’s gravitational influence; they are located at LaGrange points of Jupiter’s orbit, where the gravitational pull of the sun and of Jupiter are in 

Equilibrium. These space rocks are leftovers from the early days of our solar system’s formation; studying them tells us much about how our own planet formed.

 

We have been following the Lucy mission for quite some time, and if you are a regular OUR SPACE reader, you will recall the ambitious and exceptionally complicated flight path of the spacecraft – looping around both groups of Trojan asteroids and Earth for the foreseeable future. Each time Lucy comes close to Earth it slingshots its way around our planet, heading back out into deep space via a free gravity-assist, setting it on the correct path for an eventual rendezvous with those curious space rocks.

All over the planet space exploration enthusiasts gathered to wave at the spacecraft as it zipped around Earth. Of course it wasn’t visible with the naked eye, but people with decent telescopes who knew exactly where and when to look for it could see its transit. It’s rare for people working on a spacecraft to see it again after launch, so this was a unique opportunity for those involved in its design and construction.

The other asteroid visitor had a more low-key event: the OSIRIS-REx spacecraft, on its way back to Earth after studying asteroid Bennu in great detail, has made the first of several small course corrections, aligning its trajectory more closely with Earth. OSIRIS-REx will drop off a canister with samples it collected from Bennu. It may sound easy, but it’s absolutely not! In order for the pin-point landing via parachute to work the spacecraft has to encounter Earth at just the right distance and angle – too shallow and the sample return capsule will skip off the atmosphere like a flat rock skipping off water; too steep, and the capsule will burn up in the atmosphere.

This means several small course corrections over the next year, as engineers and trajectory planners will refine the spacecraft’s path more precisely. Those samples have travelled a long way under extraordinary circumstances, and everything now hinges on a safe drop-off and subsequent landing in the desert Southwest.

Special facilities have already been constructed at Johnson Space Flight Center in Houston, TX, all geared towards keeping those pristine samples free from Earthly contamination. A good portion of the asteroid stuff will be preserved for future generations of scientists to study – people with different experiences and even better equipment for analysis and testing. Once retrieved from its landing site the capsule will be transported to this new lab, where eager researchers armed with super-clean gloveboxes and shiny new tools are waiting for their precious cargo.

While those samples will tell us much about Bennu we have already learned a great deal from the data that has been sent back from OSIRIS-REx’ close orbits and footage from the sample retrieval. Bennu turned out to be such a loosely-packed pile of rubble that the spacecraft would have sunk right in, had it attempted an actual landing, as opposed to the quick jab and back away maneuver it performed.

Bennu will come uncomfortably close to Earth in 2135 – none of us will be alive then to witness this close encounter, but we need to leave as much information for our successors as possible, so they can take appropriate steps for further study or possibly even a deflection maneuver. Whatever they will do – they can’t smash another spacecraft into it, like we just did with Dimorphos – it would punch a hole into the rubble pile and cause all kinds of mayhem we can only try to understand with complex computer modelling. 

You can follow the Lucy mission at http://lucy.swri.edu/ (there’s lots of activities for any age plus the latest news), and keep up with the results of the DART mission at https://dart.jhuapl.edu/ .

Beate Czogalla is the Professor of Theater Design in the Department of Theatre and Dance at Georgia College & State University. She has had a lifelong interest in space exploration and has been a Solar System Ambassador for the Jet Propulsion Laboratory/ NASA for many years. She can be reached at  our_space2@yahoo.com