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June 2019: Milky way mergers, moon mining and mice

June 2019

In the show this time, we talk to Stephane Corbel about the Nancay observatory, Emma Alexander rounds up the latest news, and we find out what we can see in the June night sky from Ian Morison, Haritina Mogosanu and Samuel Leske.

The News

This month in the news: a star from far, far away, Moon news a-plenty, and updates from the New Horizon spacecraft's flyby of MU69.

First up, news that a star in our Milky Way Galaxy may not be as local as it first appears. A recent paper published in the journal Nature Astronomy by Xing et al. (open access copy here) has shown that the star, named J1124+4535, has an unusual chemistry more typical of nearby dwarf galaxies than our own. The magnitude 14 star, which is located in the constellation of Ursa Major, lies around 60,000 light-years from Earth, and was the target of a study by the Japanese Subaru Telescope.

The star was found to have unusually low levels of metals such as magnesium, but unexpectedly high levels of the heavy element europium. This elemental signature is very different to its neighbouring stars, suggesting that it might be an interloper. In general, stellar neighbours have usually formed from the same building block materials, and consist of similar chemical makeups to each other. J1124+4535's chemical makeup is much more similar to stars within the dwarf galaxies which orbit our Milky Way galaxy than our galaxy itself. Indeed, previous studies have found that the Milky Way formed by colliding with and absorbing smaller galaxies, but this new study has said it provides "the clearest chemical signature" yet of these formative galaxy mergers.

Next, we look a bit closer to home at our closest astronomical neighbour: the Moon. Firstly, there is the news that a new analysis of data from the Apollo missions has shed new light on potential lunar tectonic activity. Small shakes were found to occur on the Moon by detectors placed there by Apollo astronauts, but it wasn't clear if these were caused by the Moon itself, or external forces like meteor strikes. Now, it's been found that the epicentres of 8 of these moonquakes can be traced to within 20 miles of lunar scarps, which are fault lines that can be seen stretching over the lunar surface. The study by Watters et al. was published in the journal Nature Geoscience.

On the other side of the Moon to where the Apollo missions landed, the Chinese Chang'e-4 mission currently has the Yutu-2 rover exploring the landscape of the South-Pole Aitken basin. The basin the largest, deepest, and oldest impact crater on the Moon. This means it provides a valuable insight into the iron and magnesium rich layer of rock underneath the Moon's outer crust, called the mantle. A study published last month in Nature by Li et al. reports that materials rich in iron and magnesium have been found within the crater, and although it's not certain, they could be materials from the mantle, supporting current ideas of lunar formation and composition. It is thought that sometime early in Earth's history, we collided with another planetary body, releasing material which eventually formed the Moon. It doesn't account for the fact that the far side of the Moon has a thicker crust than the near side, but another recent study may just explain it.

Zhu et al. report in the Journal of Geophysical Research that this difference may be due to another collision of planetary bodies - this one between the cooled & solidified Moon and something just a bit smaller the dwarf planet Ceres. The team ran 360 simulations of different models, two of which ending up matching what we actually see in real life. They both involved a collision between the near side of the Moon and an approximately 500 mile wide object travelling between 14-15 thousand miles an hour. Both of these simulated collisions released debris that eventually rained back down on the lunar surface, but over on the far side, forming a layer 3 to 6 miles thick, which matches observations.

And finally, the first peer-reviewed scientific results have been released from New Horizon's New Years Day flyby of 2014 MU69. 4 billion miles from Earth in the Kuiper belt, MU69, nicknamed Ultima Thule, is the farthest ever object to have been visited by us. And ever since the data from the flyby started to be transmitted back to us on Earth, the New Horizons team have been working on its interpretation. They recently reported in the journal Science details of MU69's development, geology and composition. As suspected from the early images, it is a contact binary object, meaning that it formed from two separate objects that came together to make its iconic peanut shape. It is a lot flatter than anticipated, and the surface has features such as bright spots and patches, hills and troughs, and craters and pits. The largest depression is a 5-mile-wide impact crater. However, the surface on the whole is fairly smooth, implying that MU69 has had a relatively calm history with few violent collisions. Its red colour is believed to be caused by modified organic materials. With still yet more data to be downloaded from New Horizons (the downlink won't be complete for at least another year) there is still lots to learn about this distant object.

Interview with Stephane Corbel

Stephane Corbel gives a brief outline of the Nancay Observatory. Located in the middle of a forest in the Sologne area, some 80 km South of Orleans (or 250 km from Paris) and created in 1953 the Nancay Radio Astronomy Facility is jointly operated by the Paris Observatory, the CNRS, and the University of Orleans. The observatory has three major instruments on site with two more being developed. Stephane also talks about his own research interests and his time in Manchester.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during June 2019.

The Planets

Southern Hemisphere

Haritina Mogosanu and Samuel Leske from the Carter Science Centre in New Zealand speaks about the Southern Hemisphere night sky during June 2019.

Odds and Ends

A recent study has seen mice on board the ISS to investigate the effects of long-term spaceflight, investigating how their physical well-being and behaviour compares to mice on the ground. Mice of two age groups – 16 weeks and 32 weeks – were kept onboard the ISS for up to a month, the equivalent of a long-haul mission of several years in humans.

Overall, the study saw that the 'mousetronauts' behaved very similarly to the control group on the ground. They still spent a normal amount of time eating, grooming, and exercising, and were active during the habitat’s artificial night cycle as they would be on Earth. One unusual behaviour starting happening, though: the younger group of mice began running laps on the cage walls. It began with just a few mice running a single loop around the cage, but over time they began to run multiple loops, and it became a group activity. Interestingly, this was almost exclusively done by the younger mice.

There are a few reasons this might’ve happened. The stressful experience of being launched to the ISS and living in microgravity could be one reason, with the "looping" behaviour being like big cats pacing in a small enclosure. It might also have been a way that the mice could counteract the effects of microgravity on their sense of balance. Boredom shouldn’t be discounted either – because it had to be sent to space, the mice’s enclosure wasn’t very decorated, and they may have started running because it was a way to pass the time, as mice on the ground will do in wheels. However, even wild mice run in wheels, so it’s not necessarily a stress or boredom response – it might simply be for fun! Running like this could give the mice an exercise-induced dopamine boost; rather than getting it from climbing and exploring as they might on Earth, they could be taking advantage of microgravity to exercise in a new way. This does align with only the younger mice taking part – mice tend to exercise less as they get older.

Regardless of the cause, it’s certainly something to see – if you’re curious, have a look here.

On the 24th of May the American Aerospace company SpaceX launched 60 satellites into Low-Earth Orbit (LEO). Videos have emerged of the satellite train easily visible with the naked eye. Many researchers have expressed concern about the possible impact on ground-based astronomy of SpaceX's Starlink project, which could place as many as 12,000 satellites in orbit by 2027. You can read the International Astronomical Union's statement on the matter here.

We need to talk about space mining – as NASA gears up to send humans back to the Moon, both space agencies and private companies are looking at the Moon as a source of great potential wealth, harbouring water reserves and precious metals such as platinum. A recent 180-page report (at previous link) details how water could be extracted from the Moon to supply a lunar rocket fuelling station, and the obstacles that would need to be overcome to do this.

Another recent paper is more cautious, advising that humans should only initially exploit 1/8th of the resources available to us, leaving the rest as space wilderness, in order to avoid humanity running through its available resources too quickly. As the prospect of a true “space economy” becomes more real, these difficult conversations and decisions need to be taken sooner rather than later - such ventures promise great wealth, but also tremendous risk, as current laws and treaties governing the exploitation of space are dangerously weak.

We also take some time to mark the handing over of the show to a new set of show runners - Mike, Tiaan and Fiona. We hope you'll keep on Jodding with us!

Show Credits

News:Emma Alexander
Interview:Stephane Corbel, Tom Scragg and Michael Wright
Night sky:Ian Morison and Haritina Mogosanu
Presenters:Jake Staberg Morgan, Fiona Porter and Tiaan Bezuidenhout
Editors:Adam Avison, Naomi Asabre Frimpong, Elizabeth Lee, Tom Scragg and Hongming Tang
Segment Voice:Tess Jaffe
Website:Michael Wright and Stuart Lowe
Producer:Michael Wright
Cover art:The far side of the Moon photographed by Apollo 16, April 1972 CREDIT: NASA Apollo 16 photograph AS16-3021

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