GDACS has been reporting for the last week that Tropical Cyclone NARELLE, affecting the North-eastern coastline of Australia, has now moved along the Northern seaboard of Australia, and has finally made landfall again on the central-western coast.
On 27 March at 06:00 UTC its centre was located 55 km south of Coral Bay and 140 km north of Carnarvon, with maximum sustained winds of 150 km/h (tropical cyclone) and with gusts of up to 205 km/h.
Media reports indicate that, after crossing the northern Northern Territory, flooding occurred, particularly due to the overflow of the Katherine River.
NARELLE is expected to weaken rapidly on 27-28 March as it progresses quickly south-southeast over land, with impacts extending to the Central West and then further inland and south across the South West Land Division of Western Australia.
During the next 48 hours very heavy rainfall, destructive winds and storm surge are predicted over most of western and south-western Western Australia. Tropical-cyclone warnings are in effect in Western Australia.
Brian Jacobs, ZS6YZ, National Director of HAMNET tells me that the Northern Cape division has a new Director, in the person of Johan Britz ZR3JB, and that his deputy divisional director will be Peet Lotriet ZS3PL. On behalf of you all, I wish Johan and Peet a successful tenure in Division 3, and hope that they will be able to activate as many of the Div 3 hams as possible, to make it a dynamic and successful region.
And Sasolburg Amateur Radio Club has had a busy weekend, assisting with the annual SASOL Marathon. Members from both Gauteng and the Free State have been assisting at the race. Riaan tells me they are experimenting with a new technology in the form of a single frequency repeater, and we look forward to a report-back from Sasolburg in the next week or so.
Here’s a drastic piece of news. Writing in universetoday.com, Mark Thompson says we are slowing our planet down. The length of a day on Earth changes constantly, nudged by the Moon’s gravitational pull, shifting winds in the atmosphere, and slow churning movements deep within the planet. It always has. Day length is, in a sense, a living measurement and one that ebbs and flows with the rhythms of a restless, dynamic world. But something new is happening.
A study just published in the Journal of Geophysical Research: Solid Earth by researchers at the University of Vienna and ETH Zurich has found that our days are currently getting longer at a rate unprecedented in the past 3.6 million years and the primary cause seems to be human driven climate change!
The mechanism proposed is simple. As global temperatures rise, polar ice sheets and mountain glaciers melt, pouring water into the oceans and raising sea levels. That water spreads outward from the poles toward the equator, redistributing mass across the planet. Think of a figure skater who pulls their arms in tight to spin faster. When they stretch their arms out, they slow down. Earth is currently stretching its arms. The result is a measurable slowing of Earth’s rotation currently lengthening our day by 1.33 milliseconds per century. That sounds trivial but it isn’t.
What makes this finding remarkable is not just the number, but its context. To find out whether anything similar had happened in the past, the researchers turned to an unlikely archive, the fossilised shells of tiny single celled marine organisms called benthic foraminifera, which lived on the ocean floor millions of years ago. The chemical composition of their shells encodes records of ancient sea levels. From those sea levels, the team could mathematically reconstruct how the length of the day has changed across 3.6 million years of Earth history.
The answer was unambiguous. Nothing in that entire geological record comes close to what is happening now. Only once, roughly two million years ago, did the rate of change even approach today’s values and it was still slower. Every other period in that vast sweep of time saw Earth’s rotation influenced by natural forces alone. What sets the present moment apart is that the dominant force is no longer natural at all.
The conclusion is that the current rate of day lengthening can be attributed primarily to human activity. As lead author Mostafa Kiani Shahvandi of the University of Vienna put it, this rapid increase in day length implies that the rate of modern climate change has been unprecedented at least since the late Pliocene, 3.6 million years ago.
There are consequences however; spacecraft navigation, satellite positioning, GPS systems, and even computing infrastructure all depend on accurate knowledge of Earth’s rotation rate. As that rate changes, so does the need to correct for it, creating a cascade of recalibration challenges for the systems our modern world quietly relies upon.
Looking ahead, the numbers only get larger. Under high greenhouse gas emission scenarios, the day could be lengthening by 2.62 milliseconds per century by 2080. By that point, climate change is projected to be influencing Earth’s rotation more strongly than the Moon itself. The Moon has been slowing our planet for billions of years. We have apparently managed to compete with it in just a few decades.
And NASA’s newsletter of yesterday says that their ARTEMIS ll mission, the first crewed flight of the Artemis programme, is targeted for launch no earlier than 22h24 UTC on Wednesday 1st April, with a two-hour launch window that evening.
Real time mission coverage will stream continuously on NASA’s YouTube channel. As bandwidth allows, NASA will also offer a dedicated feed showing views from the Orion spacecraft. Daily mission status briefings from NASA’s Johnson Space Center will begin on April 2, with the exception of April 6 due to lunar flyby operations. All times may shift depending on the actual launch time and mission activities.
Throughout the mission, the crew will take part in live conversations, known as downlinks. NASA will post the exact schedule for these downlink events on the Artemis blog.
Artemis II builds on the success of the un-crewed Artemis I in 2022, and will demonstrate a broad range of capabilities needed on deep space missions. The Artemis II test flight will be NASA’s first mission with crew aboard the SLS (Space Launch System) rocket and the Orion spacecraft.
You may remember that Artemis is the Greek goddess of the hunt, wilderness, wild animals, virginity, and childbirth. She is the daughter of Zeus and Leto, the twin sister of Apollo, and a prominent Olympian deity often depicted with a bow and arrows. Artemis is renowned as a fierce protector of her sacred spaces, young women, and animals.
Let us hope that Artemis will protect her 4 astronauts as they do an orbit around the moon and return to earth safely.
This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.