Dr Megan Argo BEM

Astrophysicist

Bye bye coal

So last night the last of the UK’s coal-fired power stations was turned off for good. Ratcliffe-on-Soar is no longer generating electricity by burning coal.

Coal has been reducing in significance in the UK’s energy mix for some time, as data from the National Grid show, below.

Graph from https://grid.iamkate.com by @kate@fosstodon.org. Look at that coal line drop from a high in 2012 to nothing today, while the energy generated from wind has increased dramatically.

So what if we expanded this policy to cover the whole world?

The baseline scenario

The UK may be the first G7 country to remove coal from our energy mix, but what if every other country adopted the same policy?

Thanks to Climate Interactive and their En-ROADS Climate Solutions Simulator, we can see what the effects might be.

First, let’s look at the baseline scenario. This is what the state of the world might be if societal and technological changes were to continue at their current rate of progress with no policy changes.

Here is the energy mix going out to 2100.

En-ROADS baseline scenario showing the energy mix. In 2024, the majority of the world’s energy comes from a mix of coal, oil and gas – fossil fuels. As we move towards 2100, coal, oil and gas remain fairly steady, but the proportion of our energy from renewables increases steadily. Total energy use rises.

And here is how greenhouse gas emissions change in that baseline scenario – assuming no policy changes are made.

In this scenario, we get a global temperature change of +3.3C by 2100. Scary.

En-ROADS baseline scenario showing the change in greenhouse gas net emissions from ~40 gigatons CO2 equivalent per year in the year 2000, out to ~70 gigatons CO2 equivalent per year by 2100.

Let’s make some changes

Using the En-ROADS Simulator you can make a lot of changes. You can move sliders, you can fine-tune settings, and you can even change the underlying assumptions. It’s hugely flexible and you can simulate all sorts of possible policy interventions to see what impact they might have.

Let’s change settings to do with coal to simulate the whole world following the UK and stopping generating electricity using coal.

Here’s what the energy mix would look like.

Reducing coal causes it to disappear from the energy mix over a few years as infrastructure comes to the end of its life. By the mid-2030s there is no more electricity from coal.

What happens to that all-important measure of greenhouse gas net emissions? As we reduce coal use towards zero, greenhouse gas net emissions fall – because we are no longer burning as much coal.

Once coal disappears from the mix, the curve starts rising slowly again as energy demand continues to rise.

Importantly, the total CO2 in the atmosphere is reduced in this scenario. That’s a Good Thing.

In this scenario, greenhouse gas net emissions start to decrease over the next few years, before gradually rising again from the mid 2030s. From now on, the total emissions per year are lower than the baseline scenario.

Here’s what we changed in the model.

We’ve reduced new coal infrastructure completely, i.e no new infrastructure will be built to generate electricity from coal from now on. This policy is phased in over 10 years.

We’ve also reduced utilisation of coal processing plants and coal-fired power plants, completely ending coal utilisation as a fuel – also phased in over 10 years.

We also increase the annual retirement rate of coal plants used for electricity to 10%/year.

Coal primary energy demand reduces from 155 exajoules per year today, to zero exajoules per year by 2034. In the baseline scenario, the demand stays high and reaches more then 185 exajoules/year by 2100.

As a result you can see the coal primary energy demand (graph on the right) plummet to zero by 2034. Look at how the energy demand from coal drops to zero by 2034, compared with the baseline scenario.

Co-benefits

It’s not just about greenhouse gas emissions, although those are hugely important. When you make changes that reduce emissions, you get other benefits as a result.

What sort of results do we get?

Firstly, a reduction in the global temperature rise. The baseline model has a rise of 3.3C. Now we’ve reduced that to 2.9C. Not as far as we need to go, but it’s a start.

This comes about because of a change in the trajectory of the greenhouse gas concentration curve.

The baseline scenario has a concentration curve rising from just under 400 ppm to 800 ppm by 2100. In our scenario, this curve starts to rise less steeply, reaching 700 ppm by 2100 instead.

We also get other important co-benefits, things that have a positive impact on human health, the ecosystem, sea level rise, etc.

Here we can see how the removal of coal from the energy mix dramatically reduces air pollution from energy generation.

This graph shows a dramatic reduction in PM2.5 emissions, very small particles (2.5 micrometers or less in diameter) that can be easily inhaled and cause health problems.

PM2.5 emissions from energy generation go from between 20 and 25 megatons per year to less than 5 megatons per year by 2035 in this scenario, dramatically reducing air pollution.

This is great, right? Well, it’s a good step in the right direction, but it’s not The Solution.

Here’s the global sources of primary energy graph again. Notice what happens to the natural gas wedge (blue).

When coal use is reduced, demand for energy is still significant, so gas gets used to compensate. Unless there are also restrictions on gas, its demand will go up in response to expensive (or no) coal.

Notice how the gas wedge starts to grow once coal is removed from the mix.

How do we solve that? One solution is to tax (or restrict) the use of oil and gas as well. But that makes energy more expensive for everyone, and life more difficult for those who struggle to afford energy.

It’s a difficult problem. And as you can see here, although changing policy on the use of coal is a high-leverage solution, on its own it is far from the entire solution.

Getting closer to 2C

We need to keep coal, oil and gas in the ground for any solution to bring us close to 2C.

As the folks at Climate Interactive say “it takes many seed to plant a garden”. There is no one solution that is going to fix the climate. But removing coal from our energy production is a step in the right direction.

Here’s the scenario we built.

Want to explore further? Have a go at making your own scenario to bring the temperature rise to 2C or better? Go have a play with the simulator, and share your scenarios!

One giant step for commercial spaceflight

The space story of the week has been that of Polaris Dawn, the first ever spacewalk by non-governmental astronauts, when billionaire and mission commander Jared Isaacman and SpaceX engineer and mission specialist Sarah Gillis put their heads out of their SpaceX Dragon capsule. It probably wasn’t as spectacular as many people expected – there was no free floating around the capsule, and the astronauts didn’t leave the hatch – but it does mark a significant milestone in the rapidly developing commercial space sector.

Now, you may want to dismiss this as just another billionaire having fun with his vast wealth, but Isaacman bankrolled the mission with a view to pushing the technology, developing new spacesuit designs, undertaking scientific and medical research, as well as fundraising for a children’s hospital. There are far worse things he could be doing with his money!

And this was far from a tourist’s joyride. During their five-day mission the astronauts undertook more than 40 experiments, flew higher than any astronauts since the final Apollo mission (in 1972!), tested new communication techniques, and of course tested those new spacesuits. And they undertook a lot of training before hand, just like governmental astronauts are required to do, so that they knew what to expect (physically, technologically, and mentally) and were prepared for any number of eventualities.

Where no EVA has gone before

The jeopardy was very real. The spacesuits were an evolved design of the standard SpaceX spacesuits used for launch and reentry to protect the astronauts in case of a cabin depressurisation or change in temperature. Space agencies tend to provide astronauts with this type of suit for launch/reentry, and an entirely different, bulkier, more robust spacesuit for use on extravehicular activity (EVA, aka a spacewalk). That works, but requires more suits, and the bulky spacesuits are often not flexible enough to cope with different body types and shapes. This is a problem if you are going to want to mass produce them for your Mars colonists!

It was also different to most modern spacewalks in that there was no airlock. Go back to the days of the first spacewalks, like Ed White on Gemini IV, and no airlock was the norm, but on the International Space Station astronauts going outside for station maintenance or repairs will don their spacesuit, go into an airlock, depressurise the airlock, and then leave through an outer hatch. They have a pressurised space station to return to if they have any problems such as a suit leak, or something pokes a hole in it (or a micrometeorite or piece of space debris hits them). Dragon has no airlock, so all four crew members had to wear the suits before the entire cabin was depressurised.

And they all had to go through the preparation phase known as prebreathing, familiar to divers, where you gradually reduce the pressure and switch to breathing pure oxygen in order to remove nitrogen from your bloodstream. This reduces the risk of them suffering from decompression sickness, or the bends. Why do astronauts have to do this? Well, if your spacesuit was at atmospheric pressure it would be so stiff in the vacuum of space that it would be very difficult to move around or flex a joint. A spacesuit that can contain a pressure of one atmosphere against the vacuum of space needs to be very robust which makes it heavy and more rigid. By operating at a lower pressure, and having your astronauts undergo the required pre-breathing exercise in advance, a spacesuit can be thinner, lighter, more flexible, and much easier to use as a result.

Why it matters

For decades governmental organisations have led the way in space exploration. The Outer Space Treaty assumes this is the case, making space law an interesting and rapidly evolving field (not to mention the issues involved with space junk). Governmental space programmes are usually dependent on popular opinion for funding – either directly or indirectly (but this is not so much the case in China of course). NASA relies on congress to approve its funding, and congress are likely to think twice about giving the space programme more money when there is a cost of living crisis and they rely on votes to get elected. The European Space Agency also has a complicated landscape of national funders to negotiate.

NASA have worked with commercial firms for decades, with numerous contracts awarded to external companies for various aspects of the Apollo programme hardware for example. But the recent development and acceleration of the private space sector has enabled them to outsource more aspects of their operations. As well as the Commercial Crew Program (with SpaceX and Boeing awarded contracts to provide transportation services for crew and cargo to the ISS), there is also the Commercial Lunar Payload Service (CLPS, sending payloads to the Moon). With billionaires starting to develop their own mini space programmes through these commercial operators, we are likely to see an acceleration of activity in manned space flight.

This is exciting and is likely to help push the technology ad capabilities of the private sector forwards, but of course it comes with risks – both for those participating as private astronauts, and for those of us on the ground who may find debris coming through our roofs! The more human activity in space, the more chance of something going wrong. That will, inevitably, result in fatalities.

The bigger picture

The more activity in space in total, both in terms of human spaceflight but also the thousands of satellites being launched into space forming megaconstellations, the higher the risk of collisions and serious damage to what has become an increasingly vital part of our communications infrastructure.

There is a strong case for better regulation for orbit occupancy, collision avoidance, light pollution, and the physical pollution caused by the large increase in satellite reentry numbers. It’s time for some consideration of space as an environment.

The space sector has become vital to much of the global economy, and it will be exciting to see it develop. But we need regulation and the law to catch up with reality.

What’s in store for 2024

Happy New Year! I spoke with Glen Hunt on BBC Radio Lancashire this morning about what the Universe (and our exploration of it) might have in store for us this year. It certainly looks like it will be an exciting year for space exploration, and there are many potential discoveries that could be on the cards. Here are some things I’m particularly looking forward to.

The Sky in January

The first thing to look for is the planet Jupiter high in the sky for most of the night. Look towards the South if you are in the northern hemisphere, look to the North if you are south of the equator. Jupiter will be bright, and pretty unmistakable in the early evening.  Look with binoculars, if you have them, to see its moons (and cloud bands, if you’re lucky enough to have access to a telescope).

The ringed planet Saturn is also visible this month, but low in the South-West and fainter. Look with binoculars or a telescope for a view of the impressive ring system.  Saturn sets before 9pm and gets earlier as the month goes on, so catch it early if you can.  There is also a crescent moon close by on the 14th, with both objects low in the South-Western sky.

A sky map showing the locations of some highlights of the January sky.
The sky as seen from North-West England at 6.30pm on January 3rd. Jupiter is high in the South, Saturn is over to the South-West, and the winter favourite constellation of Orion is rising in the East. Image: Stellarium / the author.

If you’re up early, have a look for Venus (easy to spot) and Mercury (quite a lot more difficult!) low in the eastern sky before dawn.  Use binoculars for a better chance of spotting the elusive Mercury, BUT DON’T LOOK AT THE SUN with them!

One of the best meteor showers, but one of the least well-observed (thanks to the weather!), is the Quadrantid meteor shower peaking on January 4th. Unlike most meteor showers which originate from comet debris, this one is due to asteroid 2003 EH1 (possibly a dead comet, possibly a rock comet). This asteroid has an orbit around the Sun lasting 5.5 years, only taking it as far out as Saturn, unlike the majority of comets which spend most of their time beyond Pluto.   Although the body responsible was only discovered in 2003, the meteor shower has been known about since 1825. The radiant, the position the meteors appear to all come from on the sky, was in the now-defunct constellation of Quadrans Muralis (hence the name) – this location is now part of the constellation of Bootes the Herdsman today. 

The Quadrantids can be a very strong shower, with peak rates of more than 100 meteors per hour, but the peak is very short-lived and this year is hampered by daylight during predicted peak hours here in the UK. You have a better chance of seeing good activity from the Americas or Asia this year. Your best chance to view is in the early hours when the radiant is high, after 2am.  Sadly the Moon all rises just after midnight and is half illuminated, making viewing fainter meteors more difficult.  The short predicted peak of activity is between 0900 and 1500 GMT on January 4th.  

The sky looking East at 2.22am on January 4th 2024 showing the constellation Bootes, the location of the radiant for the Quadrantid meteor shower. Image: Stellarium / the author.

The sky later in the year

There will be the usual changing of the constellations as the seasons roll around. Orion is a winter favourite with lots of bright stars and a spectacular star forming region below Orion’s belt that is worth a look with binoculars or a telescope.

There are also a series of meteor showers that happen on the same dates each year as we pass through the debris left behind by comets or asteroids as they orbit the Sun. The ones to watch in 2024, aside from the Quadrantids in January, are the Perseids in mid-August and the Geminids in December. Other meteor showers will happen, but they are not predicted to be as active as these. For most details, keep an eye on the IMO’s Meteor Shower Calendar which is regularly updated.

And a couple of supermoons. While these are not particularly exciting from a scientific point of view, the full Moon is always impressive, and a full Moon at lunar perigee is bigger and brighter than usual, so will be worth a look if the skies are clear. Look up on September 18th and October 17th 2024. (And remember, the astronomical term for this is perigee-syzygy of the Earth-Moon-Sun system. Snappy!)

Spaceflight

2023 was an exciting year for spaceflight and solar system exploration missions, and 2024 is looking like it will be just as exciting. There’s certainly lots planned, both by space agencies like NASA and ESA, governments such as China, and the rapidly growing commercial sector.  Here are some things to look out for in 2024.

Europa Clipper is scheduled to launch in October, heading off to survey Jupiter’s moon Europa, an icy world that may support a sub-surface ocean.  There is a lot of interest in exploring the potential for habitability of Europa (you need liquid water, the right chemistry, and light/heat) and this probe will help with that by allowing scientists to determine the extent of any sub-surface liquid water and examine the geological processes at work.  It won’t arrive until 2030 though, but will complement ESA’s JUICE mission (launched in 2023) nicely when it does.

China plan to launch the next in their series of missions to the Moon with Chang’e 6 heading to the far side of the Moon to attempt the first sample return from the far side of the lunar surface (the side we never see from the Earth).  Likely launch in May.  We have lunar samples from the near side thanks to Apollo, but not from the far side, so comparing the two will tell us more about the history of the Moon.

June should see the maiden flight of the long-awaited Ariane 6, the European Space Agency’s replacement for the long-serving and highly successful Ariane 5 launch vehicle.  It will be able to carry a large payload to orbit, but could lose out commercially to SpaceX’s Starship once that starts flying successfully, and Blue Origin’s New Glenn heavy launcher expecting it’s maiden flight in August. Ariane rockets are expendable, whereas Starship and New Glenn are largely reusable which brings down the cost per launch substantially.

And of course the next Artemis mission taking humans around the Moon for the first time since the Apollo era, pencilled in for November 2024 (but, like all launches, this could slip).  Artemis 2 will be the first crewed flight of the Orion capsule, and see the first humans go beyond low Earth orbit since 1972, taking four astronauts around the Moon and back in what is likely to be a highly-watched mission.  Expect stunning photographs of the lunar surface!

As well as large programmes like Artemis, NASA have also commissioned a series of commercial companies to provide lunar landers for robotic and autonomous probes through the Commercial Lunar Payload Services (CLPS) programme.  The first of these missions, Peregrine 1, is due to launch on January 8th and will carry two rovers, several sensors, and a collection of time capsules. Several other launches are planned, expanding NASA’s existing work with outside commercial contractors that goes back decades.

We are also likely to see both another record year for satellites launched into low Earth orbit (making the risk of collisions ever more likely, and astronomy more challenging) and more new private operators beginning launch operations, including multiple commercial launches to the Moon, adding further competition to the market.

Biosignatures?

And finally (in Jodcast tradition), there is certainly a lot of interest in looking for evidence of biological processes in space, and it’s possible 2024 might be the year we first find solid evidence of biosignatures somewhere other than the Earth. This could be in samples from Mars, or it could come from further afield in the form of spectroscopic signatures from the atmospheres of exoplanets.

Since the 1990s we have discovered more than 5000 exoplanets around stars other than the Sun. The more we look, the more we find. Remember though that this is still challenging – we had the telescope for almost 400 years before we discovered the first solid evidence for extra-solar planets! And as is usually the case with new discoveries, we found the easier ones first.

Astronomers are using powerful telescopes with very sensitive spectrometers to split up the light coming from the exoplanets. This is challenging because a planet only reflects the light from its host star, rather than emitting its own light, so it is much fainter than the star and much harder to detect (which is why it took almost 400 years to find one!). But if you can do it, and split the light into its constituent colours to make a spectrum, you can then look for the signatures of chemicals in the planet’s atmosphere.

Some chemicals are associated with life, so those are the ones to look for. Many of these chemicals can also be produced by non-biological processes too, so finding a signature in the spectrum is only one part of the puzzle in many cases. But if we find one of them, it will certainly be tantalising.

There are also a lot of astronomers looking for signatures of life in the cosmos using a rather different method. Instead of looking for biosignatures, they are looking for technosignatures – evidence of advanced technology from signals that could not be produced in any natural way. This could be radio signals (like the radio and TV transmissions we have been sending into space for many decades now), or something more advanced such as a powerful beacon, or evidence of megastructures, or even evidence of some cataclysmic event.

It may sound like science fiction, but these are genuine research projects. The probability of finding either a bio- or technosignature may be low, but should we find evidence of life elsewhere in the cosmos, the implications really would be tremendous.

That’s not all folks

There are plenty more exciting events to look out for in 2024, from super moons to comets, results from previous missions, new images from JWST that will be as astonishing as ever, and many, many rocket launches. But it’s lunch time here, so I’ll leave it there for now. If you made it this far, thanks for reading! What are you looking forward to this year?

Fireworks? In October?

No, not Bonfire Night. We’re talking celestial firework displays! It’s October, and once again we’re coming up on the time for the annual Orionid meteor shower.

There’s been a trend over recent years of various parts of the media getting a bit hysterical about various astronomical phenomena, and in some cases hyping them up waaaaaay beyond any sensible justification and raising expectations to totally unrealistic levels. So if you’ve arrived here having heard stories about how spectacular the Orionids will be on October 21st, should you believe the hype? TLDR: no, but…

What is a meteor, anyway?

A meteor is actually quite mundane: a small piece of rock, generally smaller than a grain of rice that disintegrates as it flies through our upper atmosphere while travelling at many kilometres per second.

You can see meteors on any clear night of the year, all you have to do is find somewhere dark, look up, and be patient. These are called sporadic meteors and are just the detritus left over from the formation of the solar system, or debris from collisions between rocky bodies in the solar system. In the absence of something like a planet to crash into, they just float gently around in space not doing very much.

Usually you have to wait a while before you see a sporadic meteor, although because they are distributed randomly in space they don’t turn up a regular intervals and you may see a handful close together if you’re lucky.

Meteor showers, on the other hand, can be much more spectacular, and come round predictably at the same time each year. In the case of the Orionids, that time is October 21st – or thereabouts.

Origins of the Orionids

All meteor showers are the result of the Earth passing through regions of space with a higher than average concentration of these dust and rock particles. This happens because stuff gets left behind when comets (and some asteroids) go about their normal business on elliptical orbits around the Sun.

Comets are a bit like giant, dirty snowballs, containing large quantities of both ice, frozen gases, dust and rocks, and other volatile substances. We currently know of more than 3800 comets in the solar system, some of which we have actually visited giving us a much better idea of their chemical composition. Samples collected by the Stardust mission even finding the presence of the amino acid glycine, one of the fundamental building blocks of all life as we know it.

Comets spend most of their lives in the far reaches of the solar system where conditions are very cold indeed. Since comet orbits are elliptical, and centred on the Sun, their orbits also take them into the inner solar system for some of the time.

As a comet approaches the inner solar system it get closer to the Sun and so absorbs more solar radiation, heating the nucleus and causing some of the ice to sublimate – that is it turns directly from a solid ice into a gaseous vapour. As the ice turns to gas, the dust and rock particles embedded in it are released and float away, leaving a trail of debris behind the comet as it travels around the Sun.

 When the path of the Earth happens to cross one of these debris trails, we see an increase in meteors coming through our atmosphere.  This is the origin of a meteor shower, and explains why they are regular with predictable dates of activity.

The Orionid meteor shower is the result of debris left behind by Halley’s comet, one of the most famous comets in our solar system. The comet only returns to our skies once every 76 years (and is not due back until 2061), but the Earth travels through the debris trail each year, giving us the regular Orionid shower in October, and also the less well-known Eta-Aquariid shower in April/May.

Variations

A given meteor shower may not have the same level of activity, year to year. Some years a shower might be fairly unimpressive, with peak rates of only a few per hour. Other years we might have a much larger spike in activity and see rates of several hundred an hour. Rarely we might see rates of more than 1000 per hour – rarely seen meteor storm.

Imagine an aeroplane passing through the sky on a sunny day, leaving a contrail behind it in the sky. If you sit and watch that trail, it slowly expands, becomes less dense, and eventually disappears. Comet debris trails are a little like that (although not as easy to see, being made up of tiny dark particles of rock!).

As that trail ages, it gets less well-confined, the particles move apart slowly. Each time the comet comes round on its orbit, it deposits a fresh trail of denser debris along its orbital path. Add in the fact that the gravitational influence of the likes of Jupiter (and any other planet the comet comes relatively close to) can alter the trajectory of the comet, and you start to get a sense of why the number of meteors we see varies from year to year as the Earth passes though denser or less dense parts of the debris trail.

Very clever folks (such as the IMCCE meteoroids and meteors group) take observational data on the number of meteors observed each year (collected by seasoned observers – and you can help!) and build models of the debris trails for each meteor shower, and use those to make predictions about the number of meteor showers we are likely to see the following year. They are usually pretty accurate, but sometimes we see unexpected spikes in rates that were not possible to predict from past data alone – so it’s always worth a look.

What to expect in 2023

This year we are expecting good observing conditions on the peak night of October 21st, with the Moon at 48% illumination but setting before midnight.  The best time to observe will be after midnight when the Moon sets and the constellation of Orion will have risen – this is the location of the radiant of this shower, the location on the sky the meteors appear to come from, and what gives the shower its name.

Some showers are particularly spectacular with more than one a minute on average.  We’re not expecting that this year for this shower, with predictions of around 20 or so per hour.  However, any shower has the potential to be spectacular, so it’s always worth a look!

The best way to observe is to find somewhere away from street lighting, wrap up warm, and look up!  Obviously, you also need clear skies, but don’t worry if October 21st is cloudy as the streams of debris that cause most meteor showers are wide enough to provide activity over more than one night.  Catching meteors takes patience, but can be worth the effort, and can contribute to citizen science projects.

Clouded out? I expect a lot of us (here in the UK, anyway) will be, thanks to Storm Babet. You might have more luck in other parts of the world. The nice thing about the Orionids is that they are equatorial, meaning you can see them from both the northern and southern hemispheres.

If you do miss them, don’t despair. There are plenty more meteor showers in the calendar!

In December we will see the return of the Geminid meteor shower with a predicted peak of ~150/hour! Much more spectacular! The Moon will also be favourable as it will be very close to the Sun and not up during most of the night, aiding dark sky conditions which help you see the fainter meteors.

So, if you miss out this weekend, make a note in your calendar of December 14th, and make sure you remember to take a look!

The FCC issues first fine to a satellite operator

The US Federal Communications Commission (FCC) issued a press release on October 3rd 2023 describing the first time they have fined a satellite operator for failing to properly de-orbit one of their old satellites.  The fine might be small, but this is the first time they’ve used their regulatory powers to issue such a fine and so is a significant moment for the space sector.

We’re used to thinking of space as a big place, with distances dwarfing those we are used to on the Earth.  But Earth orbit is a finite resource.  Just as you can only fit so many cars on a motorway such as the M25, you can only put so many satellites into orbit before you risk collisions.

Since Sputnik 1 in 1957, humans have launched more than 15,000 objects into orbit.  Today, less than half that number are still operational.  Some defunct satellites have returned to Earth, many have burned up in the atmosphere, but a significant number are still in orbit many years, sometimes many decades, after they ceased operations.  

The debris problem

Active satellites are one thing, but decommissioned (or malfunctioning) satellites are quite another.  Once out of fuel, or uncontactable by ground stations, defunct satellites become nothing more than heavy, fast-moving, uncontrollable, dangerous projectiles.

Accidental collisions have happened, several times in fact, involving operational satellites, non-operational satellites, or mission-related debris (including parts of spent launch vehicles).  Debris has also been created accidentally through satellite break-up, and deliberately via anti-satellite weapons tests by various states, most recently in 2021 where the resulting debris threatened the safety of the International Space Station and the astronauts on board.

How much space junk is up there?  NASA’s Orbital Debris Program Office monitors and tracks space debris and estimates that there are approximately 500,000 marble-size fragments, and over 100,000,000 objects of 1mm or less in Earth orbit.  Even tiny fragments of material can do significant damage when moving at typical orbital speeds of several kilometres per second.  More debris makes space more hazardous for all operators.

Decommissioning satellites

With so much orbital debris, the question of how to deal with decommissioned satellites becomes vital for the sustainable use of low-Earth orbit (LEO) and the long-term viability of space-based activities.  Guidelines exist in many parts of the world (for example the European Space Agency has an office with a remit for space safety and requirements for their own satellites), but global standards (and enforcement of those standards) is not easy.

Satellites in LEO can be disposed of by giving them a nudge that sends them towards the atmosphere.  The drag provided by even the rarefied environment at the top of the atmosphere is enough to cause a satellite re-entry. 

Most satellites will burn up during their fiery descent, resulting in no debris hitting the ground, but creates a cloud of chemicals from disintegrating metal, electronic components, solar panels and batteries that slowly disperses in the air.  With many more satellites ending their operational lives this way, the long-term viability of dumping all this material in the atmosphere also needs to be considered.

Larger satellites do result in some debris making it through the atmosphere. Back in 1979 the Skylab space station broke up in the atmosphere, scattering debris across southern Western Australia centred on the small community of Balladonia. The local council issued NASA with a fine for littering. More recently, the launches of more than one segment of the Chinese space station in 2021 and 2022, resulted in 18-tonne rocket bodies re-entering the atmosphere in an uncontrolled manner, scattering debris over large areas.

Satellites in geostationary orbits are much higher above the surface of the Earth.  Bringing them down in the same way as satellites in LEO would require significant fuel for the necessary change in velocity (known as delta-v), as well as presenting the hazard of crossing the orbits of satellites operating at lower altitudes.  More often, defunct satellites in geostationary orbits are disposed of by sending them further out, requiring a much smaller delta-v and less fuel, into what is known as a disposal orbit, some 300km further up.

What happened with EchoStar-7

The subject of the FCC fine, Echostar-7 was a geostationary satellite operated by Dish Network, used to provide television services to the United States.  It had a mass of just under 2000 kg, excluding propellant, and spent its operational lifetime in geostationary orbit, some 36,000km above the surface of the Earth.  Launched in 2002, it was originally planned to operate for 12 years but was given a license extension in 2012 taking its operations through to May 2022 when it was expected to transfer to a disposal orbit.

However, in February 2022 the satellite operator, Dish Network, determined that the satellite has less propellant remaining than it should have.  Without enough propellant remaining on board, reaching the required altitude for the safe disposal orbit was no longer possible.  In the end, the satellite only reached an altitude 122km above the geostationary position, far short of the intended orbit required in their orbital debris mitigation plan.

So what?

Why does this matter?  With so many satellites in space, and the number increasing rapidly thanks to the advent of large constellations of satellites being launched by companies such as SpaceX, OneWeb, Kuiper (due to launch their first satellite this week) and others, the risks of a catastrophic collision increase all the time.  The risks are greater with defunct or uncontrollable satellites as they are unable to be moved to avoid a collision.  Failing to reach the 300km mark means that the satellite could become a significant hazard for operational satellites in geostationary orbit.

Satellites orbit at high velocity, travelling several kilometres per second.  When they collide the resulting debris also travels incredibly fast in many directions.  Fast-moving debris has a lot of energy and any impact with another satellite, functional or not, will result in yet more fast-moving debris.  Because of the significant risks this poses, companies launching satellites must take steps to ensure the safe and responsible disposal of them when they reach the end of their operational lifetime.

While many countries and space programmes have their own voluntary guidelines and codes of conduct for satellite operators, this is the first case of such an operator being fined by a regulator for breaching licence conditions relating to disposal, a significant moment for the rapidly developing commercial space sector.

The risks are significant.  Debris can damage and destroy other satellites, taking out vital communications infrastructure.  Astronauts on board the International Space Station regularly have to perform manoeuvres to avoid either debris or active satellites that come within safely limits.  Satellite operators themselves are increasingly having to undertake collision avoidance manoeuvres because of other functional and non-functional satellites.  

The modern world relies heavily on satellite communications.  If enough debris accumulates in Earth orbit it will become difficult, if not impossible, to operate communications networks on which so much of modern life has come to rely, but also to send spacecraft (and potentially humans) out into the solar system. 

The fine is small in this case, just $150,000, but it is a clear signal that the FCC is willing to use its regulatory powers to fine operators who do not take seriously their responsibilities to the sustainable use of Earth orbit.  

It is worth remembering that the FCC only has jurisdiction over US-based operators.  To be effective as a deterrent and drive more responsible behaviour globally we need larger fines, and international cooperation between agencies and regulators so that our near-space environment isn’t trashed the same way we have destroyed so many habitats here on the Earth.  

The consequences of not acting would be disastrous for communications, banking, Earth observation, disaster relief, and many other sectors that rely on satellites and their applications.  Now is the time to act.

Exploding stars

If you’ve looked at any astronomy-related news over the last few days, you’ll have spotted that a supernova has exploded in a nearby galaxy, and astronomers are getting excited about it. Supernovae are not uncommon (we discovered more than 2000 of them just last year), but some get astronomers more excited than others. Why is this one interesting? Read on.

We think of stars like the Sun as lasting forever. On human timescales, that’s ok since most of them have lifetimes of millions to billions of years – our own Sun has been shining for some five billion years, and probably has enough fuel to last another five billion or so. But they are transient things, like everything else in the Universe, just on timescales it is difficult for us mere mortals to grasp. Even astronomers struggle!

Stellar lifecycles

Stars are giant fusion reactors, fusing hydrogen in the core to make helium, and releasing energy in the process. It’s this energy release that powers the heat and light we get from the Sun, and what makes all the other stars shine. Stars continue this fusion process for as long as the conditions are right in the core. You need a lot of hydrogen under very high pressure and at very high temperatures. Eventually, the hydrogen runs out and a star starts to die.

The way a star ends its life depends very much on one parameter: its mass. The amount of stuff that makes up a star. It’s a simple parameter, but it determines an awful lot about a star’s properties, lifespan, colour, luminosity, end point, and much else. Most stars are mostly composed of hydrogen (~75%) and helium (~25%) with small amounts of other elements. Stars that have formed recently (in cosmic terms) have a greater proportion of these “other” elements, for reasons I’ll come to, but they are still mostly hydrogen and helium.

When a star runs out of hydrogen in the core, the fusion process slows down, reducing the amount of energy released per second. That energy, in the form of photons, keeps the star from collapsing under gravity for most of the star’s life. When the number of photons decreases, the star can no longer counteract the relentless pull of gravity, and it starts to contract. In science terminology, the star is no longer in hydrostatic equilibrium.

As the star begins to contract under gravity, the pressure in the core begins to rise, the temperature also goes up, and we get to the point where conditions in the core are extreme enough that the fusion of helium can begin. This process also releases energy (although not at the same rate) and stops the collapse for a time. There isn’t so much helium though, so the helium-fusing period of a star’s lifespan is relatively short. The shell of mainly hydrogen around this hotter core is now also hotter, and can start undergoing hydrogen fusion too. Again, it doesn’t last anywhere near as long as the original hydrogen burning phase – a phase we call the main sequence lifetime, and which makes up the longest part of any star’s lifetime.

For stars like the Sun, that’s almost it. The helium also runs out, the core starts to collapse again. As the outer layers expand and cool, the star becomes a red giant. The core continues to shrink, eventually becoming a hot, dense object known as a white dwarf. The outer layers eventually drift off to form a (poorly-named) planetary nebula, the white dwarf core slowly cools and fades away over billions of years.

But for stars greater than a certain mass (somewhere around eight times the mass of our own Sun) the end is much more dramatic. These stars continue the fusion process, with the core developing like the layers of an onion, with each progressive layer fusing heavier and heavier elements as they are produced by the layers above them, all the way across the periodic table, up to iron. Iron is interesting, as its the first element in the periodic table where you cannot release energy through fusing it to create a heavier element. To fuse iron, you have to add energy. There’s nowhere inside a star for that injection of energy to come from, so the fusion process stops.

If there’s no fusion in the core, there is nothing stopping the layers above collapsing under gravity. And that’s what happens. Catastrophically.

The outer layers start to fall as the source of photon pressure to keep them up diminishes, until the iron core collapses under its own weight*, resulting in energetic shockwaves that literally rip the star apart. This is what we call a core collapse supernova. The physics of this are fascinating, and the theoretical modelling has come a long way in recent years as computers have become more powerful. (Other types of supernova happen too, astronomers recently detected radio observations from a thermonuclear supernova for the first time, but that’s for another day.)

Now, supernovae are not rare events. As I mentioned at the top, we discovered over 2000 supernovae just in 2022, with many more than that identified as candidate supernovae. Many of these are discovered by automated surveys that scan the sky each night looking for new objects, or astronomical objects changing in brightness. But some are discovered by dedicated amateurs with good equipment and an excellent knowledge of the sky.

SN2023ixf

This supernova, SN2023ixf, was discovered by one well-known supernova hunter, Koichi Itagaki from Japan. He’s discovered quite a few over the years! It is located in one of the spiral arms of the galaxy M101, also known as the Pinwheel galaxy due to its appearance, and it is pretty gorgeous:

M101 or the Pinwheel Galaxy, as seen by Hubble. Credit: ESA/NASA/Hubble.

The galaxy is some 21 million light years away, so the light reaching us now (including the light from this explosion) left the galaxy 21 million years ago and has only just reached us. Looking out into space is looking back in time, we only ever see the Universe as it was in the past.

So, if we discover so many of them each year, why are astronomers excited about this one in particular? Well, for one simple reason: its proximity. While we discover a lot of supernovae, most galaxies are a lot further away than M101, so most supernovae are also much further away than this. The closer a supernova is, the more easily we can study them, and the more detail we can achieve with our observations. A nearby event means that our telescope have better resolution (our images have more detail in them) and we collect more photons (an event of the same brightness twice as far away will appear four times fainter).

This galaxy has also been host to several supernovae over the years. Since we’ve been watching, we’ve spotted at least five in M101, the most recent being SN2011fe discovered in (no surprise!) 2011.

What we know so far

SN2023ixf was first discovered on May 19th and is being observed by astronomers around the northern hemisphere, so what do we know so far?

It’s a core collapse supernova, having gone through the evolutionary stages described above. Estimates from early modelling suggest that the progenitor star might have been about 15 times more massive than the Sun before it exploded. It has been getting brighter, heading for a peak magnitude of around mag 10 – far too faint to be seen with the naked eye, you’ll need at least a 4-inch/20-cm aperture telescope (and some patience!) to spot it.

There are lots of images over on David Bishop’s excellent Bright Supernova catalog page for this object, and plenty of updates if you do a quick search. It will likely stay bright form some weeks, so (as Catherine Heymans said on 5 Live at 8.50am this morning), if you have a telescope gathering dust in the attic, you might want to drag it out and have a look.

Why are they important?

So what’s all the fuss? It may be close, but it’s just one of many hundreds of thousands – so what?

Supernovae are cosmologically important. That nuclear fusion process I described makes elements up to iron in the periodic table. To get anything heavier than that, you need even more extreme conditions than in the core of a massive star, and that’s where supernovae come in.

In a supernova explosion, the extreme conditions created in the shockwave and subsequent blast result in a rapid burst of nucleosynthesis, creating elements much heavier than iron, including many that are important to the creation of things like the computer you are using to read this!

All of those heavy elements, as well as the stuff up to iron created before the explosion itself, get thrown out into the surrounding gas that make up what astronomers call the interstellar medium. This process is called enrichment, adding heavy elements to a gas that is mostly made of hydrogen and helium.

Stars form from the interstellar medium. Over dense regions in the gas start to clump together, gravity increases and more material gets pulled in. Slowly, over hundreds of thousands to millions of years, the gas accumulates, the temperature goes up, the pressure in the centre increases, until you have a hot ball of gas where nuclear fusion can begin in the core – et voila, a star is born!

The gas around the core then goes on to form planets in many cases. If that gas cloud only contains hydrogen and helium, you only get gas giants forming. If the gas also contains heavy elements in sufficient quantities, produced in previous supernova explosions, then you get rocky planets forming too.

If you’ve ever heard Carl Sagan talk about us being made of star stuff, this is what he means. Much of the chemicals that make life possible, that make up the crust the Earth, that make up you and me, and our computers, were made inside massive stars and released into space in supernova explosions.

Don’t panic?

Our own galaxy, the Milky Way, is also forming stars, some of which are massive enough to go supernovae in this way. We actually haven’t had one in the Milky Way since 1604 so we’re rather overdue for one.

Some stars we know of are big enough to explode this way. Betelgeuse is a red giant that has got astronomers very excited in the last couple of years by behaving in a way that could signal its impending doom. It hasn’t exploded yet, but keep an eye on it.

If a supernova did explode in the Milky Way it would likely appear extremely bright due to its closeness. Astronomers would go bananas.

Supernovae are energetic explosions, generating blasts of neutrinos, as well as strong radiation across the electromagnetic spectrum – radio, infrared, visible, ultraviolet, X-rays, gamma rays. Any planets in the neighbourhood would get a good dose of radiation.

Don’t worry though, there are no stars in the vicinity of the Sun that are big enough to be a threat to life on Earth by going supernova. The supernova candidates are all far enough away to not be a threat. They would be pretty cool to watch though!

Edit: I just spoke to BBC Radio 5 Live about this supernova! Listen back (5.50pm): https://www.bbc.co.uk/sounds/schedules/bbc_radio_five_live

Edit: thanks to Jost Migenda for spotting my mistake!

A day at the Palace

Between January and July 2021, during a Covid-19 lockdown and beyond, I organised and ran a programme of virtual planetarium shows over Zoom, talking to groups of Rainbows, Brownies, Guides and Rangers across the whole of the UK. Over six or so months, this programme delivered more than 60 shows and reached over 1400 girls. As a result of all this, I was awarded a British Empire Medal in the Queen’s Birthday Honours in June 2022.

Megan in a hat with my new shiny medal pinned to my jacket.
BEM presentation day at Tatton Park, October 2022

When you are awarded an MBE, OBE, CBE, etc., you get invested into the order by one of the working royals. Not so for the British Empire Medal. Instead you get your medal presented by your local Lord Lieutenant, and an invitation to attend a Garden Party at Buckingham Palace!

I was presented with my medal by the Lord Lieutenant of Cheshire at Tatton Park in October last year. The image on the left was taken that day. I really enjoyed meeting the other awardees and hearing about the excellent things they had done and for which they had been awarded the same medal. As guests, I took my partner, my mum and her husband, and Gail, my Guide leader from when I was young, and who has been a very special friend ever since. The presentation was followed by afternoon tea with the other awardees and our guests, as well as various local dignitaries. I spent a while talking to the Lord Lieutenant about the need to encourage girls, and young people generally, to take an interest in science.

May 3rd 2023 was the date of the Garden Party at Buckingham Palace. On the invitation, the dress code said “day dress” for women. I don’t wear dresses very often, not since primary school anyway, they’re just so impractical. But this was a rather special occasion, so a dress it was. Rather than buy one though, I decided to make one. Out of space fabric, of course.

It was a lovely afternoon, with perfect weather (although a little chilly in a dress!). The gates opened at 3pm, tea was served in the tea tent (sandwiches, cakes, tea, apple juice, barley water, ice cream), with music provided by two military bands in tents on either side of the green. The bands were so far apart, to communicate to each other when they were playing they each had a flag pole – the flag was raised when the band played, and lowered when they finished. The gardens were lovely, well worth exploring if you ever get the chance. Lots of bluebells, as well as azaleas, camellias, rhododendrons, roses, and a rather marvellous wisteria.

All in all, a lovely event, and I felt very honoured to be there. I didn’t get to meet the King though, I just saw the back of his head over a crowd of people, but it didn’t matter.

Being in London just before the first Coronation in 70 years was also a bit mad. The infrastructure for the festivities was being assembled around us, lots of roads were closed, and there were huge numbers of tourists. Leaving a restaurant on Tuesday evening, we bumped into the rehearsals for the coronation procession and got a sneak preview! Rather than look for a taxi, we walked down Whitehall towards the noise of the drums, then followed the military bands as they marched down Birdcage Walk back to the barracks. Very impressive to watch.

Thanks to all the groups who hosted me for my planetarium shows back in 2021, thanks to all the girls who watched the shows and asked brilliant questions, thanks to my UCLan colleagues who helped out with shows when demand outstripped the number of available evenings I had, and thanks to my other half for putting up with all my evening activities (and cooking dinner!). And thanks to whoever nominated me, it’s all been very special and I’m happy I was able to do something useful during such a bizarre time.

I’m still happy to visit groups to do planetarium shows, I just don’t have an actual planetarium! I do have a laptop though, all I need is a screen or white wall, a projector, and a way to make the room dark… get in touch if you’d like a visit, especially if your Brownies want to do their Space badge!

And if you know anyone who has done something amazing, do consider nominating them for an award.

More asteroid near misses – and one hit!

The early hours of January 27th 2023 saw the closest approach to Earth of asteroid 2023 BU.  The fact that this particular space rock was only discovered on January 21st, just a week earlier, combined with it passing just 3,600 km from the surface of the Earth (0.03x the distance between the Earth and the Moon) got the media rather excited.  It’s trajectory brought it closer to the Earth than orbit of our geostationary satellites, but still well above the 200-300 km of things like the International Space Station located in low Earth orbit.  Given how far apart geostationary satellites are, our communications infrastructure was not in any significant danger (this time).

This particular asteroid was estimated to have a diameter of 4-8 metres and was travelling at a speed of around 9.3 kilometres per second as it passed by.  This might sound big, but it’s tiny by asteroid standards.  If it had hit the atmosphere, it would have most likely burnt up entirely, leaving only tiny fragments reaching the ground, if at all.  For comparison, the rock that disintegrated over Chelyabinsk in 2013 was estimated to be 20 metres in diameter – that one exploded in the atmosphere, showering small chunks of debris over the town.  Assuming a similar density to the Chelyabinsk rock, asteroid 2023 BU likely had a mass of less than 1,000 tonnes.

The asteroid moves rapidly past the Earth at closest approach before moving away again and slowing down.

Animation showing the close approach of asteroid 2023 BU on January 27th 2023. Image credit: ESA.

The thing is with an asteroid passing this close to a much larger object, the encounter will change its future orbital trajectory.  Prior to this encounter, observations show that this asteroid orbited the Sun every 359 days.  Observations made after the encounter allowed experts to model its new orbit, finding that it now orbits the Sun every 425 days.  It won’t be back at the Earth now until December 24th 2029 when it will be some 14 million km at closest approach.  Nothing to worry about.  In fact, they’ve modelled its position all the way to 2139.  The closest it will pass to us in that time is 528 thousand km in January 26th 2066.

The thing is, this happens all the time.  As of today, according to the IAU’s Minor Planet Center, there are 31,207 known near-Earth asteroids, 850 of which are larger than 1 kilometre in size, and 2,328 potentially hazardous asteroids.  And we’re finding new ones all the time.  Just this year (we’re still only in February) we’ve had at least eleven objects pass closer than the Moon, at least five of which were not discovered until after closest approach!  Again, don’t panic, they’re all pretty small and would be highly unlikely to do any damage.

2023 CX1 entering the atmosphere.  By Wokege.

2023 CX1 entering the atmosphere on Feb 13th 2023. By Wokege.

One of these actually impacted the atmosphere.  Asteroid 2023 CX1 was discovered less than seven hours before impact!  Again, don’t panic, it was tiny, about 1 metre in diameter, and burned up as an impressive fireball somewhere over the English Channel / Northern France (above).  You can see reports of sightings on the IMO fireball report catalogue.  This was only the seventh impacting asteroid to be discovered before it actually hit the atmosphere.  It’s still pretty difficult to find these things in advance.

If you want to look at the population characteristics, JPL’s Center for Near Earth Object Studies has some data and charts you can play with – I’ve included a couple below showing the discovery rate of NEOs, colour-coded by survey, and the size distribution.

Bar chart showing the increase in discoveries in recent years.

Discovery rate of NEOs, colour-coded by survey, dated Jan 31st 2023. Credit: CNEOS.

The above plot shows the increase in discovery of near-Earth objects.  The surveys that have discovered the most objects are the Catalina Sky Survey and Pan-STARRS, although many are still discovered by amateur astronomers – including 2023 BU and 2023CX1!  This is one of the science goals of the Vera C. Rubin telescope‘s Legacy Survey of Space and Time (LSST), to make an inventory of the solar system.

There are far more small NEOs known than large ones.

Size distribution of NEOs discovered to date, dated Jan 31st 2023. Credit: CNEOS

This one shows the size distribution of NEOs discovered so far.  As you can see, there are not many in the 1000+ metres category – luckily!  Those are the ones most likely to cause us damage, but they are also the easiest to spot.  The thing with space rocks is that they are rocks.  Rocks are usually pretty dull looking, they are often dark colours and don’t reflect much light.  That is a problem when your trying to find them with an optical telescope – they don’t reflect much light, so are pretty faint and therefore difficult to detect.

If you’re a keen astronomical observer and are looking for a project, here’s the Minor Planet Center’s list of NEOs needing confirmation.  More observations are always welcome, helping to pin down asteroid orbits, and you don’t need sophisticated equipment to contribute.

Keep watching the skies – there will be more of these!  But they will get harder to spot as we launch more and more satellites, and install more and more lights.

?

Space Juice

It’s been a busy week or so for news stories about the solar system!  Last Friday was the list time we would get to see Juice, Jupiter Icy Moons Explorer, before it was shipped off to Kourou in French Guiana for launch on an Ariane 5 rocket in April.  Juice is heading off to the Jupiter system to explore the planet, its magnetic fields, and some of its largest moons: Europa, Ganymede and Callisto.  This mission has been in development for years, having been selected in 2012 as the first “large-class” mission in ESA’s Cosmic Vision 2015-2025 programme, and has contributions from both NASA and the Israeli Space Agency.

Jupiter Icy Moons Explorer

As BBC local radio stations amusingly described it last Friday, Space Juice will achieve several firsts.  It will be the first spacecraft to orbit a moon in the outer solar system – we’ve orbited our own Moon, but never the moon of another world.  It will also be the first flyby of the Earth-Moon system (called a lunar-earth gravity assist), which is a flyby of the Moon first and then another flyby of the Earth just 1.5 days later – by doing this manoeuvre, Juice will save a significant amount of propellant.

Flybys are always important for getting to the outer solar system, they can save you a lot of propellant which gives you more mass to use for funky, exciting science instruments!  In this case, although Jupiter is only about 600 million km from Earth, there is no rocket powerful enough to go directly there.  By making flybys of Earth (August 2024), Venus (August 2025), and Earth again (September 2026, January 2029), Juice will travel more like 6.6 billion kilometres!  It’s worth it though, for the extra science payload.

What’s it going to do?  Juice will give us the most detailed view of Jupiter and its icy/water world moons (Ganymede, Callisto and Europa).  Jupiter is the archetype gas giant planet.  We keep finding Jupiter-like planets around other stars, but they are very difficult to study due to their distance – it’s very hard to image them.  Jupiter is much easier to study, and learning more about this solar system giant can help us understand those Jupiter-like exoplanets in more detail.  All three moons thought to have subsurface oceans of liquid water, so are important places to go searching for evidence of life.

Exploring moons

Jupiter and its moons are like a mini solar system.  Jupiter sits in the middle of a dancing melee of smaller rocky objects in (almost) circular orbits around it.  Why will Juice visit these three moons in particular?  Well, we think they all have some liquid water below the surface.  And they are all quite different, so comparing them will be really interesting.

Europa has an obvious icy crust, so the surface features are actively changing.  Imagine watching the ice creak and move slowly in Antarctica – but on a planetary scale!  Juice will make a couple of flybys of Europa to search for biosignatures, to see how much water there might be under the surface, and explore the moon’s geology and activity.  Europa is very close to Jupiter, it’s a very harsh environment so Juice will only make two flybys of this moon.

Ganymede is older and has a less active crust.  It has an older surface which is rocky, rather than icy, and gives us a window on a geological record that spans billions of years of solar system history.  It’s also the only known moon with a magnetic field, implying that it has a molten core like the Earth.  Juice will explore Ganymede’s magnetic field, look for subsurface pockets of water or evidence of a sub-surface ocean, measure its complex core, its interaction with Jupiter, and help us determine the potential for habitability – now, or in the past.

Callisto has the oldest known surface in the solar system.  It appears heavily cratered, an indicator of its age, and is inactive (no volcanos on Callisto!).   Given its age it will help us explore the history of our own solar system.  It may also contain a salty subsurface ocean, something else the sensors on board Juice will be looking for.

After launch (hopefully!) in April, Juice will then set off on its eight-year cruise out to Jupiter.  On the way it will have to brave harsh radiation and temperature environments (+250C at Venus flyby, -230C at Jupiter!), but it has been designed to cope with all this.  For its science operation phase it will be a long way from Earth, so it will need a powerful antenna to send back data, and largely autonomous systems due to the time delay.  Sunlight is 25 times weaker at Jupiter than on Earth, so it also has very large solar panel arrays (an area of 85 square metres!) producing 700-900 Watts (plus batteries for use during eclipses).

Jupiter will be a busy place over the next decade or so.  Juno is already in orbit, mapping Jupiter’s gravity and magnetic fields, and NASA are also sending Europa Clipper which will arrive in 2030and will work in collaboration with ESA’s Juice.  Keep an eye out for results from these missions!

For much more on Juice, its instruments and mission goals, see ESA’s Juice Launch Kit.

Remembering the Queen

Even when you know a death is coming, it is still a shock.  Along with the rest of the country, and with many around the world, I was very sad to hear the news last night that the Queen had died at Balmoral.  In a way, it was good to know she died somewhere she felt at home, surrounded by her family.  May we all be so lucky.

Seventy years on the throne is quite something.  She was one year younger than my grandad, so reading back through his memoirs is a reminder of how much the world has changed over her reign.  Her dedicated life of service was an inspiration to many and made her a powerful role model.  You may not be a supporter of the monarchy, but you can’t deny that.

My grandad met her once, when they were both young children.  During his early life, my grandad’s parents ran a farm at Dinnet, not far from Ballater.  The landowner and local member of parliament was friendly with the royal family who would often visit Dinnet House when they were in residence at Balmoral.  On one occasion, when a visit coincided with the strawberry crop, the young princesses came with a driver to the farm to collect some fresh cream from the the dairy.  While waiting for the cream, the princesses and their governess got out of the car to look at the young calves in the next field and my grandad and his sister joined them.  In his memoirs, my grandad notes that “they were young children just like we were, but very much tidier in appearance, and rather better spoken“.

I can understand the Queen’s love for Balmoral and the area.  If you’ve never been, it really is worth a visit.  Lochnagar is an imposing mountain and the scenery in the area is just gorgeous.  Last time I was there the gardens were coming to life in early spring, and we saw a red squirrel scrambling nervously up a tree near the gates.  The river Dee runs through the grounds of the estate and the colours of the granite rocks in the water inspired the design of the Balmoral tartan.  (The whiskey from the local distillery isn’t bad, either.)

Many decades later, I met the Queen too.  The merger of UMIST and the Victoria University of Manchester necessitated a new royal charter, which was presented by the Queen at the University on October 22nd 2004.

The Queen shaking hands with PhD students Paul Carr and Megan Argo.

The Queen meeting representatives of the faculty of Engineering and Physical Sciences during the ceremony to mark the granting of the new Royal Charter to the University of Manchester, 22nd October 2004.

I didn’t get to hear the speeches as I had been asked to be one of two representatives from the faculty to meet the Queen after the ceremony and talk to her about the research going on at the University.  We were briefed before hand and were very nervous, but she was (as many people have noted) extremely good at putting people at ease.  I’m sure you would get good at that too, with such a full diary of public engagements spanning decades.

Grandad kept a photo of the occasion on a shelf for years.  He also noted in his memoirs (and told me on several occasions) that he was “disappointed that Megan did not tell the Queen (as I told her to) that she was looking forward to becoming her Astronomer Royal“.  Sorry grandad, I don’t think that was ever even remotely likely!

Along with many, many people, I feel there is something missing today.  The Queen has been there my entire life; we all knew she wouldn’t last forever, but it is still strange to think she has gone.  Having lost two members of my own family this year, my thoughts are with the royal family today.

Rest in peace, Your Majesty, thank you for everything.

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