The Scruffy Astronomer

The Hubble Space Telescope has been in orbit since 1990. That's incredible for the high-radiation environment it has to work in. After a shaky start, it's been sending mind-boggling photos back to Earth for more than 30 years. Image: NASA But a few weeks ago the payload computer stopped. The computer equipment on board the HST has many levels of redundancies: there are backups for their backups. So the first problem is identifying the component that has failed. But even after they've found the problem, NASA can't just go up there and start soldering. Since the retirement of the Space Shuttle, they have to do it all remotely. What's currently up there is going to have to do. What's more, while many astronomers on Earth communicate with their equipment at a distance, remote maintenance is difficult when it might be the remote computer that's gone on the fritz! There are a few suspect parts. Initially, NASA though it may have been a bank...

There have been a lot of spacecraft arriving at Mars in the last few months. Since February, the US, China and the United Arab Emirates have all arrived there. The US and China have now landed, and the UAE will remain in orbit. The soviets did it ages ago, of course. Here's a model of their probe. This is all very cool, but more interesting is how they reached Mars, and why all three arrived at about the same time. How do you get there? I probably don't have to say this, but getting to Mars isn't as simple as hopping in your car and driving to Mildura. One of the complexities of rocket science is that to have fuel available for manoeuvre s such as landing, you have to lift that fuel off Earth's surface, and that takes ... well, fuel! How do you get to Mars using the absolute minimum amount? You figure out the shortest way. Mars is one planet out from the Sun. Because of this, it orbits slower than Earth. A Mars "year" is about 23 Earth...

The Tianhe-1 is the first part of the new Chinese space station. If you like, it's an orbiting foundation, but more accurately, it's called a "core module". At 16.6 metres in length and 22.6 tonnes, it's big already, but it'll grow as the Chinese Space Agency adds modules. It's got several docking ports to allow expansion as well as providing parking space for service vehicles. It was launched on 29 April on top of a Long March 5B heavy-lift rocket. The launch went well and the upper stage of the Long March rocket reached the planned orbit. After dropping the payload, it was probably meant to restart and slow down. This way it would fall back to Earth not far from the launch point. This didn't happen, and the 21 tonne rocket remained in orbit, rising to over 240km, and then dipping to about 150km every 90 minutes. The rocket was also tumbling, indicating it wasn't under control. With each dip in altitude, the rocket brushed the upper atmosp...

The Hubble Space Telescope has been working now for over 20 years. Some (maybe all) of the photos it's sent back have been incredible, and the science it's produced has developed our knowledge of the cosmos considerably. But it's also getting a little old. In 22 years, technology has marched quite a bit, meaning the instruments we put up there are not exactly cutting edge. But second, Hubble's spectrum is limited to UV and visual frequencies. We're starting to get curious about the infrared - that is, what's going on on the other side of the visual spectrum. The James Webb Space Telescope (JWT) is nearing completion, and is due to be launched in October this year. This telescope is intended to complement and replace Hubble. The telescope itself is large. Its mirror has a "sort-of diameter" of 6.5 metres, but it's not circular, Rather, it's an array of 18 hexagon-shaped mirrors, 1.32 metres across. To give you an idea of th...

Padraic Koen posted this beautiful photo taken from the helipad at Arkaroola in South Australia. I often joke that my "office" is at the ASV's dark sky site in Heathcote, but Padraic's beats that by light years . It was at 3:59am on 6 December, and the camera, with its 11mm lens, was facing West-Northwest. Arkaroola is at the northern end of the Gammon Ranges, seriously isolated in the outback. The settlements of Copley and Leigh Creek are over 100km to the West-Southwest. These places produce pretty much zero light pollution, so the Arkaroola skies are about as dark as you'll get anywhere on the planet. There are a few things going on in this picture. First, the Moon was rising in the Northeast, out of frame to the right. This is shining gentle light onto the terrain, and the ten-second, ISO800 exposure picks out some features on the ground. This is pretty much my favourite part of the sky. At the top, Orion is dominating. Orion contains all sorts o...

The International Space Station is now 20 years old. It orbits the Earth every 90 minutes or so, and while it doesn't go past everyone every time, there are quite a few opportunities to see it - as long as you don't live in Canada, Northern Russia or anywhere in Scandinavia. Mike from Port Macquarie got a fantastic photo earlier this month. It's the best one I've seen so far. I contacted Mike to find out how he did it. ... and you can take a photo like this yourself! The ISS is about 110 metres across. When it goes over soon after sunset or soon before sunrise, it stands out against a dark sky. If the light is at just the right angle, it can be brighter than Venus. The ISS moves at about the apparent speed of an airliner, but it makes no sound, and has no flashing lights. It's quite serene. But Mike's photo was a challenge. It's a bit like photographing an A380 from Melbourne while the plane is flying over Devonport in Tasmania! Mike uses an app called I...

Back in December 2018 I wrote about the encounter between the NASA's probe OSIRIS-REx and the asteroid Bennu . After a lengthy journey from Earth, the probe had settled into orbit and was about to begin studying the asteroid. Since then, we've learned a number of unexpected things. First, there's water there. Not a lot, but it looks like water is turning up all over the solar system. But there may have been a lot more water there in the past, with evidence that it may have actually flowed through Bennu's interior. Second, there's organic carbon there. Because carbon forms the backbone of all organic molecules such as sugars and alcohols, this might hold some clues to the origins of life. Third, and the most interesting thing (for me, at least), was that Bennu is a remnant from a larger asteroid that had been blasted to bits in a collision. This gave Bennu not only its odd diamond shape, but also its relatively fast spin. That would have been quite a sight. ...

For something a little different (we're still in lockdown in Melbourne and I can't get out to a dark sky site), here's a story about spin stabilisation and how it doesn't always work. This is when an object spins while in free-fall, rather than tumbling. Tumbling, as the name suggests, is when the object spins in more than one axis. During the Second World War, bomb makers had realised that bombs that tumbled through the atmosphere on their way to their targets did not detonate reliably. In the same way, artillery shells wandered off their targets when they tumbled. Making these missiles spin through their flight stopped them from tumbling. Shells could be spun by rifling in gun barrels, and bombs had fins that caused their spin, as well as pointing them towards the ground. So in 1958, when the US launched their first satellite, Explorer 1, engineers decided to stabilise the final stage by spinning it along its long axis. Unlike Sputnik 1, Explorer 1 had a "rock...

As a brief follow-up from my post the other day about the possible return of the second -stage booster from the 1966 Surveyor 2 mission to the Moon, I noticed that Starman is about to fly past Mars. Remember back in March 2017, when engineers at Elon Musk's SpaceX were looking for a dead weight to test their Falcon Heavy launch vehicle? They used Musk's own Tesla Roadster, sending it on a largely unplanned mission to (or beyond) Mars. The range it had was not accurately known. Typical for Musk, the theatre of the mission was considerable. References to Douglas Adams' Hitchhiker's Guide "trilogy in five parts" were everywhere, and Isaac Asimov also rated a mention. Yes, of course it was a publicity stunt, although it did have some scientific legitimacy. To cut a long story short, the mission was an outstanding success. The Falcon's upper stage (together with the Tesla) escaped Earth's orbit - just like the Centaur booster in 1966 - and transferred ...

Surveyor 2 - ghost rocket or space junk? In September 1966, the US launched a rocket carrying a Moon probe known as Surveyor 2. The mission was to land on the Moon and transmit data back to Earth. So-called "soft landings" had been done twice before, once by the USSR and once by the US. The cold-war space race was on. The plan was that the probe photograph its own landing site. To do this, it would land, pause, then fire its engine and take off again, landing a second time. During this brief "bounce", the probe would examine the ground where it had landed. Nothing was known about the Moon's surface. If humans were to walk there, it was important to know that they wouldn't fall into a subsurface cavern or be lost in quicksand. The probe was going to use photographs and radar to examine the structural integrity of the surface. But it was all a moot point. The Centaur booster successfully lifted the probe out of Earth orbit and towards the Moon before sepa...

I've posted a couple of times about space junk, useless stuff left in orbit, a couple of times before. Space junk can grow on its own, through collisions which cause more debris which is less predictable. But worse, collisions cause more collisions, and might at some stage cause a "cascading Kessler Syndrome", effectively closing space. But at this stage it's deliberate collisions that might be the threat to watch. At least four countries are developing kinetic anti-satellite weapons, also known as "hit-to-kill" weapons, either against incoming ICBMs, or other satellites. Debris from a Chinese test in 2007 damaged a Russian satellite two years later. More debris from the same test passed within 6km of the International Space Station in 2011. More recently (in March 2019), India successfully demonstrated its own capability. The test was deliberately carried out in a low orbit to limit the spread of debris, but recent reports from the Arms Control Wonk claim t...

Satellites need electricity to run electronics, mostly for communications and control systems, but also, if they're up there for scientific purposes, for whatever experiments they're doing. Most - not all - of these satellites use solar panels as power sources. You probably know that the Voyager spacecraft used nuclear cells for power. That's because they were travelling out of the solar system and sunlight out there is very weak. Space agencies have to transport large solar sails into orbit. Clearly, these can't be sent up all in one piece. The solar sail has to be broken down into components, the largest part being small enough to fit into a small capsule. But the real complication is figuring out how to assemble all these small parts using the very least amount of work.  If the panel is going to the ISS, some of the work can be done by astronauts, but even then, their time is very precious and work done outside is very difficult and dangerous. But most panels are des...

Remember last April, I was talking about space junk and the possibility of a " runaway Kessler Syndrome "? This is when the amount of space junk flying around means anything in orbit will be destroyed by debris. In the worst case scenario, humans could be stranded on Earth because of the Orbiting Cloud of Death . (I ought to write a SciFi novel with that premise.) If there's going to be a Kessler syndrome, the most likely cause will be debris created by satellites being destroyed by existing space junk. Wikipedia lists at least five instances where satellites have been damaged or destroyed in collisions with space junk or "micrometeoroids". As well, space shuttles and the ISS have been hit and damaged by tiny bits of debris. This photo was taken from the Space Shuttle in 1998. I think it's a thermal blanket from the same mission, not an alien spacecraft. Seriously. Search for "Black Knight satellite conspiracy theory". Another source of space junk ...

  I guess most of you have heard about how Elon Musk’s SpaceX company has launched a second “train” of satellites, augmenting the ones sent up last month. The photos and videos look pretty freaky. You’ve probably also heard astronomers and astrophotographers moaning about it. Well, just how much of a problem is it? A quick answer is in my photo. I was up at the dark sky site a short while back, photographing the Horsehead nebula. Just as an aside, the Horsehead is my all-time favourite object, just pushing out the Fighting Dragons. I know it’s a lot of people’s favourite too – but it’s undeniably super cool. But I digress… I was taking five-minute sub-exposures using my three various narrowband filters. All up, I got about 50 of these for stacking, which I thought was a pretty good haul for a Summer night. But as you can see, I lost four of my subs to satellite photobombing. I’ve stacked the four frames I lost into this photo. I don't even think these are SpaceX satellites...

27 November 2019 You probably know that I'm a bit of a Nordophile. I lived in Norway for three years, but sadly never got to visit the archipelago of Svalbard up near the North Pole. This is, you may recall, the location of Brage Bærheim's astroterrestrial photo that I featured a while back. It seems there is a weak point (what that means I'm not sure) in the Earth's magnetic field near Ny-Ålesund, a settlement on the West side of Svalbard. During auroras, the solar wind gets in through this weak point and interacts with the atmosphere, ionising it and drawing some of it out into space along the magnetic field. A while back, scientists at Ny-Ålesund launched two sounding rockets into an aurora. They were able to take readings in a very narrow time period, and gathered data about what they call the "atmospheric fountain". That study is ongoing. However what they do know is that the amount of atmosphere lost into space is only a tiny proportion of th...

15 November 2019 Voices from interstellar space. Back in 1977, NASA launched the twin probes Voyager 1 and Voyager 2. Voyager 1 left the solar system in August 2012, and now, nearly 18 billion kilometres from the Earth, Voyager 2 has finally left as well. It's outside the "heliosphere", or the bubble of particles ejected from our Sun, and so is now in interstellar space. How can we tell that Voyager 2 has crossed the heliosphere? The probe has a few sensors that are still working. These can measure the temperature, pressure and density of plasma particles blown out of the Sun. Scientists at NASA describe the plasma inside the heliosphere as "solar wind" and the particles outside as the "galactic wind". The characteristics of these winds are different. Voyager 2's measurements all fell significantly in around November 2018, and levels have remained low. This indicates that it wasn't just a random zone of low plasma density, but Voyager...

14 October 2019 You can do this! I've seen few photos of the Space Station taken with affordable gear before. This one is fantastic. Jim Hammond took this shot from his driveway in Oregon in the USA (yeah, I rarely post photos from outside of Oz). Jim's rig is a Sky-Watcher 102mm Maksutov on an EQ2 mount (www.opticscentral.com.au/skywatcher-102mm-eq-maksutov-cassegrain-telescope.html). The Mak has a mylar sun filter (like www.opticscentral.com.au/skywatcher-127mm-solar-filter-for-maksutov-cassegrain-telescopes.html), and on the back was a Nikon DSLR. Everything else was technique. Jim knew the exact moment the ISS was going to pass in front of the sun from transit-finder.com, given his location. On the day, Jim used a watch synchronised to the Internet. For Iridium flares, I've used my GPS. Jim needed a really fast shot or the image would blur. Experience suggested 1/1000s at ISO 400, but that depends on your scope. On continuous shooting, Jim's camera t...

A few people have asked me why I haven't posted content relating to the 50th anniversary of the Apollo 11 mission. It's a good question.   I remember watching telecasts of the moonwalks. We were all sitting cross-legged on the floor of a combined classroom, watching a huge black and white television on an impossibly tall trolley. We had a sense of history. I guess there are two main reasons why I'm not posting Apollo content. The first is that there is no shortage of posts, tweets, documentaries and news articles about it, so there's no real need. The second reason, which is probably more fundamental, is that I feel fairly ambivalent about the whole space program. Without a doubt, the whole space race demonstrated what an entire country (or two if you include the USSR) can achieve when properly motivated. The technological advances that came out of the various programs (not just the Apollo missions, of course) were huge. The whole purpose of the space race was...

27 May 2019 Yikes! Did NASA just dust New York? No, they didn’t. Don’t worry. It was all an exercise. But it makes a fun read! Recently NASA and JPL hosted a conference on planetary defence – against near-Earth objects, that is, not aliens. Part of the five-day conference was a simulation of the discovery of an object on a collision course with Earth. Each day, more information was presented, and experts were asked what the best course of action would be, including options to deflect or “disrupt” the asteroid. They also discussed what would be at risk, and how to manage and mitigate damage. The hypothetical narrative that the experts were subjected to was this: In March 2019, the asteroid is discovered, and is estimated to have an impact probability of 1 in 100. At this point, most of the effort is focused on determining the fine orbit, and the size and mass of the asteroid. By July 2019, additional information has increased the probability of impact to 1 in 10. This is whe...

17 April 2019 You might remember a few weeks ago I was talking about space junk? I included a photo of a chip taken out of one of the windows of the International Space Station. This was caused by a tiny flake of something (they think it might have been paint) that struck at about 26,000 kilometers per hour. Well, in more recent news, India has demonstrated that it's now the fourth nation that has the ability to shoot down a satellite in low Earth orbit. They did this using a kinetic strike, which is also known as "hit to kill". Simply put, all this involved was a well-aimed rocket that collided with the satellite, blasting it to pieces. Sounds familiar? Hit-to-kill strikes are the same as any other collision, and are a source of dangerous space junk. According to the US Air Force Space Command, India's demonstration created more than 250 (some say 400, but it depends on the size we're tracking) pieces of dangerous space junk in low Earth orbit - which i...