Helping NASA’s LUCY Mission

By Matt Woods

In late June, I took a phone call that allowed me to fulfil one of my greatest wishes. That wish was to help do research for NASA. To be honest, I had given up on that dream. Going through school, mathematics wasn’t really my strong suit. While I loved space and astronomy, I couldn’t see a path for me to become an astronomer, for some reason as much as I tried and studied, I just couldn’t do the mathematical equations that were necessary.

On the 22nd of June I took a call from Kosta Servis from Curtin University, he told me that he and Dr Hadrien Devillepoix from Curtin’s Desert Fireball Network were going to go up to Shark Bay in late July to record the occultation of the binary asteroids Patroclus and Menoetius for NASA’s LUCY Mission and were needing to borrow a telescope. Occultations occur when an object passes across the line of sight between an observer and another object. In this case, Patroclus and Menoetius were going to pass in front of a star called UCAC4-224-161658.

I said to Kosta, that we would be more than happy to help them by lending them one of our Celestron CPC 1100 telescopes and let them know that we had a second CPC 1100 telescope and if they didn’t mind, I’d love to come and help record the occultation, to which they said yes. Recording the occultation is important to NASA’s LUCY mission as this is the first space mission to explore a population of asteroids known as the Trojans. The Trojans are outer Solar System asteroids that orbit the Sun “in front of” and “behind” the gas giant Jupiter. By recording these occultations, we can work out not only the shape of these asteroids that LUCY is going to visit, but also work out their mass and shape which will allow the LUCY team to plan out the fly-bys of some of these Trojan asteroids. LUCY is on a twelveyear journey to eight different asteroids, with Patroclus and Menoetius being visited in 2033.

This was the third occultation and the more important out of four occultations that occurred over Australia in twenty-nine days. The reason for it being more important was that across one path the width of Shark Bay, you could record both occultations of Patroclus and Menoetius without having separate teams in different locations, unlike the other three occultations where the occultation paths for Patroclus and Menoetius were separated by hundreds of kilometres. These two occultations were to occur at 8 minutes past midnight on the 23rd of July with Patroclus’s occultation lasting 8.8 seconds and Menoetius’s occultation lasting 8.4 seconds.

As I began talking to Kosta, I got into an email conversation with Dr Mark Buie from the Southwest Research Institute in Boulder, Colorado. Marc is an amazing astronomer who has discovered over 950 asteroids and worked on the New Horizons mission to Pluto and the Kuiper Belt, where he discovered Pluto’s moons Nix and Hydra, as well as discovering the Kuiper Belt object 486958 Arrokoth which the New Horizons spacecraft would visit after Pluto. He and his team were coming to Australia to record all four of these occultations for the Lucy mission and was looking for a place to store their equipment as there was a two-week break between the second and third series of occultations. we said we’d love to help them out and they could store the gear at the Observatory I also mentioned that I was working with Kosta and Hadrian. Once Marc was in town, we caught up at Core Cider near the Observatory and we decided to work together.

Lucy flying past Patroclus and Menoetius. Image Credit: NASA’s Goddard Space Flight Center/Conceptual Image Lab/Adriana Gutierrez

The Emu abd it’s eggs (LMC and SMC galaxies) at Whale Bone Point. Image Credit: Matt Woods

Over the next two weeks, equipment was assembled and tested with no help from the cloudy weather, and camping gear was gathered as we were going to be camping all the way. Our ride up to Shark Bay was the mighty mare called Rhonda, a Toyota Land Cruiser. We left Perth on Wednesday the 20th of July and stayed at campsites near the Murchison River and up at Big Lagoon near Denham at Shark Bay. At Big Lagoon we were able to do a final test and thankfully we did as we worked out a few bugs in our plans that hadn’t arisen in the previous testing. On Friday afternoon we drove to Whale Bone Point which was going to be our campsite for the night and the location of the telescope that Hadrian was going to run. Once we’d had dinner and helped Hadrian set up his telescope, Kosta and I got into Rhonda and drove 20 kilometres North to Eagle Bluff Lookout which is the location where Kosta and I would record the occultations. Set up went well and we were tracking the star for 3 1/2 hours before we needed to do the final Test.

At that point, that’s when the poo hit the fan. Hadrian was using a different CCD camera to Kosta and me which was lent to him by Marc Buie’s team. That CCD camera was a QHY 174 GPS camera which records the GPS and time stamps in each of the image’s metadata. Time stamping is very important when it comes to working out the shape of both asteroids from this occultation. Because everyone is spaced out roughly 12 kilometres apart, they will see the occultation start and finish slightly differently, which allows us to work out the shape of the asteroid, but everyone must be using the correct time. Unfortunately, the ZWO CCD camera Kosta and I were using didn’t have a GPS module to it so we had a GPS device that had an LED light that would flash on the minute attached to the top of the telescope.

In our final test, we found out that the GPS device was faulty, and the LED light was not flashing so we weren’t getting keyframes (Images that are brighter due to the flash from the LED) at the start of every minute.

The path of the occultations. Image Credit: Google Maps

The Mighty Mare Rhonda. Image Credit: Matt Woods

Our locations for the occultations. Image Credit: Google Maps

That meant we had to carefully remove the dew shield from the top of the telescope, and by the time we had got the new GPS device attached, the telescope’s corrector plate had completely dewed inside. We’re in deep trouble here because it was now only 15 minutes until the occultations, and we had to remove that dew which we’re able to do in about 7 minutes with a hair dryer on its lowest setting hooked up to Rhonda.

Once the telescope was ready again for the occultation, I sat down at my laptop and couldn’t believe the sight that greeted me where there was once a U-shaped pattern of stars smack bang in the middle of my screen, we had a completely different field of view now. In the attempt to fix the GPS device and remove the dew, we accidentally knocked the telescope out of position, and I spent right up to the point of needing to press the record button trying to find the star we needed to track. As I pressed the record button, I felt so dejected as the last few weeks, I had been so worried that I might be the one that stopped us from successfully recording these occultations and my worst nightmare had seemed to come true, I just wasn’t sure that I’d got the star back into the view of our camera.

To make matters even worse, at the end of the second occultation, one lone giant cloud started to move over the patch of sky where the telescope was pointed. We couldn’t believe it the rest of the sky was completely clear, but this one cloud had to try and ruin our fun. We drove back to the campsite dejected as we thought we’d failed but we were glad, as Hadrian was able to record both occultations, so we had our celebratory drinks and did a bit of astrophotography. After a very late start to the morning, we started to make our way back to Perth. Hadrian took the chance to check Kosta and my data that we’d recorded and to our massive relief, we had recorded both occultations and the keyframes were working so the data that we had collected was usable. We also found out the cloud had covered our field of view only one or two seconds after the second occultation had finished.

When we got to Geraldton we stopped off at the motel where mark and his team had checked into and dropped off our data to him. Marc had already started inputting the data that his team had collected into a plotting program, so we were able to see some of the shapes of Patroclus and Menoetius. Patroclus looks like a rugby or AFL football, while Menoetius looks absolutely beaten up so it’s a good thing, we’re sending a spacecraft out to see what they really look like. Mark also let us know that they’ll be writing a paper on these occultations and that we would be co-authors on that paper which I couldn’t believe but was so thankful for. As we left Marc, we all promised to stay alive to at least 2033 so we can see these two asteroids up close, and we continued the journey back home. It was a great trip to be on and I’m so glad that I was not only able to complete one of my dreams, but I also was able to make a few more friends.

Star Adoption Tours

Our star adoption program provides a unique gift and is a way to recognise a family member or friend through the adoption of a star. All available stars in the program are between the magnitudes -1 and 4.9 (visible to the naked eye) or 5.0 and 7.9 (visible in binoculars), all in the Southern Hemisphere. The individual star adoption package includes:

A certificate (suitable for framing) with star name and coordinates, and the duration and purpose of the adoption.

Private star viewing night for the recipient and 3 guests within 12 months that include several other seasonal objects and will be scheduled when your chosen star is available at a suitable time for viewing

A planisphere (a device to show what constellations and stars are in the sky at any time)

Star charts and coordinates showing where the star is located in the night sky, as well as being shown how to use these at the star viewing night

Please note: Perth Observatory’s Star Adoption program doesn’t offer international naming rights to the star as there are no internationally recognised naming rights to the stars. The program is run by the Perth Observatory Volunteer Group Inc, and the income goes towards the Observatory’s not for profit, public outreach program.