19th March 2019 – Meteor fireball detected off Kamchatka
Interesting news article on the BBC about a fireball detected on the 18th December last year in the Bering Sea off the east coast of Russia’s Kamchatka peninsula, a place I happen to know well. The fireball was detected by “military satellites” – presumably those monitoring for nuclear tests. Nothing seems to have been felt or reported locally (we sometimes forget how big Earth really is).
The interesting thing is the size of the explosion: 173 kilotons TNT equivalent, which is ten times the Hiroshima nuke and the second largest meteor detected in decades, almost half the size of the huge Chelyabinsk blast caught on all those Russian dashcams.
In this case, the meteor was just that – it exploded in the upper atmosphere (25.6 km alt) over the ocean. But it suggests we might not be as safe from small asteroids as we like to think now the near-Earth objects (NEOs) are supposedly mostly known. So how big was the meteoroid? We can get an idea from some simple physics, by assuming the energy released was all the kinetic energy of the meteoroid.
The news report suggests a speed of 32 km/s and we know the energy released in kt, so first we can first convert back to SI units. 32 km/s = 32000 m/s. The energy in joules of a ton of TNT (according to Wikipedia) is 4.184x109 J, so the energy released by the meteor was 173 x 1000 x 4.184x109 x 0.907 (tonnes/ton) = 6.565 x1014 J.
We can rearrange the kinetic energy equation, E = ½ mv2 in terms of mass to give m = 2E / v2
Then plugging our values back in, we get mmeteoroid = 2 x 6.565 x1014 / 320002 = 1282,000 kg.
Working back using density (probably between rock and iron) and volume, that gives a meteoroid likely less than ten metres across!
That’s really tiny! No wonder it wasn’t a tracked NEO asteroid! It’s chastening to realise how much kinetic energy such a small thing contains at cosmic velocities.
In, fact the BBC reports that the ultimate goal is to detect 90% of NEOs above 140m in size. However, an asteroid of that size would likely make it to ground level and would release many megatons of energy. Gulp.
17th March 2019
A local news outlet in Boca Chica is reporting that SpaceX’s Starship Hopper test bed is about to begin tethered tests of its Raptor engine(s). This is a big deal, because Raptor is completely new and the basis for SpaceX’s new Super Heavy/Starship launch system.
Raptor uses a design – full flow staged combustion – that is radical and has never flown. It should make the engine more efficient and/or more reliable.
Remote Boca Chica is on the far south tip of Texas, just east of the Mexican border, where SpaceX has a test facility on the coast.
14th March 2019
In my latest book, I write about the truly crazy situation that no human has been more than a few hundred miles from Earth in pushing fifty years. When and if we do, there may be no astronaut alive from the previous deep space era to greet the returning crew. Unless …
NASA has a planned (though likely un-crewed) circum-Lunar mission (you know, like Apollo 8 … in 1968!) next year, EM-1. But given the endless delays to the Space Launch System (SLS), I’ve never taken that very seriously. But now, reports are coming out that NASA may open it up to commercial tender. And that basically means ULA vs SpaceX (again).
If NASA sticks with the planned Orion capsule and service module, ULA would for sure need at least two and possibly three missions to hurl the hardware aloft on a Delta Heavy, which can only put about 10 tonnes into trans-lunar injection (TLI).
However, the situation with SpaceX is less clear. The weight of the capsule and service module at some 26 tonnes seems to be slightly beyond the limit for Falcon Heavy in fully expendable mode. From what I can see, Heavy could loft approx. 21 tonnes to TLI. Could SpaceX push the envelope (maybe with a Raptor for the second stage)? Or could SpaceX even get the Super-Heavy booster flying by then? Given their almost unbelievably aggressive development schedule so far, maybe.
Either way, if NASA decides to go commercial for this mission, it looks potentially good news for fans of deep space exploration: a successful un-crewed EM-1 might lead to a crewed version, esp. given SpaceX’s low costs. On the downside, it could be another nail in the proverbial for SLS.
12th March 2019
SpaceX has been in the news a lot lately. Meanwhile, Tesla is having another tough week, with the press again smearing Musk as some pot-smoking flake. Oddly, the same journalists write glowingly how SpaceX is saving the US manned space program. Hello! It’s the same guy!
Talking of SpaceX and Tesla, I wonder what the “… and one more thing” will be at Thursday’s big reveal of the Model Y? Could it be the SpaceX Roadster? Musk was tweeting (what else?) about it again last month.
In case you’re not up to speed, this will be a SpaceX branded version of Tesla’s new Roadster hypercar. The SpaceX Roadster will have cold gas thrusters like a SpaceX booster, powered by a SpaceX COPV. The thrusters should give the car extra acceleration (as if 1.9 seconds 0-60 isn’t quick enough) and perhaps better cornering and braking too.
Much more importantly (?!), Musk has promised those thrusters will let the SpaceX Roadster hover! I take a look at whether this is even possible in this short piece:
11th March 2019
My new book is now live on Amazon (Kindle only for now, paperback to follow):
9th March 2019
Gave my second talk of the week about the strange and fantastical legacy of Percival Lowell, the subject of my new book: The Roads from Mars Hill.
The audiences and venues were geographically close, but very different! First came a room full of nuclear physicists at the University of Manchester’s futuristic Dalton Institute Cumbria Facility. Second was my twice-a-year spot at Low Gillerthwaite Field Centre’s dark sky event: children, chickens, soup-and-parkin, muddy boots and a roaring fire.
8th March 2019
SpaceX’s perfect launch, docking and recovery of the Dragon capsule paves the way for US manned space flight again. More significantly for me, it gives SpaceX the headroom to focus on Starship, the Moon and Mars!