The nerd community had a bit of news earlier today: a meteor streaking across the skies of Russia. Since everyone in Russia seems to have a dashcam (apparently it’s a car insurance requirement over there due to police/judicial corruption), we even got footage of it:
While the meteor didn’t cause any damage itself, the sonic blasts were significantly more destructive; current reports seem to indicate around 400 injured, mainly from broken/falling glass. Not surprising: the sonic wave arrived ~30 seconds after the meteor passed over, and a lot of people would have been at various windows having a look at what had just happened (and in their defence, if I saw a massive flare like that, with a beautiful contrail in its wake, I’d be out there as well trying to get photos for this blog!). It’s similar to tsunamis: most fatalities happen to people who chase the receding sea, unaware that the reason for the receding waters is that they’re about to un-recede in a rather spectacular and destructive way.
(You may want to turn your speakers/headclamps down for the sonic blast videos, unless you either enjoy extremely loud bangs or you’d like a crash course in Russian swear words…)
Of course, being Russia and therefore having Russian temperatues, blown-out windows are a serious problem in winter, so hopefully the emergency services there are more jacked up than ours.
The big question here is: is this related to the asteroid 2012 DA14? For those of you living under a rock, it’s an asteroid with an estimated diameter of 50 meters, an estimated mass of 190,000 metric tons — and it will be passing approximately 27,000 kilometres from Earth’s surface in a few hours (19:25 UTC, 21:25 South African time). Over on Bad Astronomy, Phil Plait seems to think that it’s totally unrelated:
For one thing, this occurred about 16 hours before DA14 passes. At 8 kilometers per second that’s nearly half a million kilometers away from DA14. That puts it on a totally different orbit. For another, from the lighting, time of day, and videos showing the rising Sun, it looks like this was moving mostly east-to-west. I may be off, but that’s how it looks. DA14 is approaching Earth from the south, so any fragment of that rock would also appear to move south-to-north.
Not necessarily. Imagine a basketball in front of you. That is the Earth. Now draw an imaginary line from your nose to the left side of the basketball. Your line is going east to west. Now draw another line to the right of the basketball. Your line is now going west to east. Same point of origin. Same basic direction of movement. Different perceived trajectory for those living on the basketball.
Information on the meteor is still rather sketchy, although we may get a better picture in the next few days — it appears that the meteor broke up in the atmosphere and may have rained down some chunks on the ground. If true, and if and when those chunks are found, we may learn more.
For now, I’m going to have to end off with this image by EUMETSAT, showing the vapour trail:
The most obvious bad news is that this is quite dangerous, as this object has now become a collision risk to other satellites.
The first collision between two satellites happened in 2009, when an American 1,235-pound Iridium communications satellite—launched in 1997—collided with a dead 1-ton Russian satellite launched in 1993. At the time, NASA blamed the Russians.
The collision wasn’t only bad for the functioning Iridium, but also to everyone else. Space is a big place, but it’s full of trash. And like that accident proved, collisions happen.
We can track small pieces of debris, but space crashes generate particles that we can’t monitor. The thousands of objects that may result from such an accident put other satellites, spaceships and the lives of astronauts at risk.
There’s probably several of you wondering how a small piece of space debris can be so deadly, and the answer is a simple one: the speeds involved. Earth’s escape velocity is 11 km/s, so that’s kind of a minimum speed limit for anything wishing to escape the planet’s gravitational influence. In practice, satellites will be moving slower than that, since they don’t need to escape Earth’s gravitational influence; they need only to obtain balance between Earth’s gravitational pull and the inertia of the satellite’s motion.
But that’s still fast. The closer the object is to Earth, the faster it needs to be moving to obtain that balance, since the gravitational influence is stronger. I spend a bit of time tinkering with NASA’s orbital velocity calculator, and discovered the following:
The International Space Station, which is maintained at an orbital altitude of between 330 km and 410 km (if Wikipedia is to be believed), has an average orbital velocity of 7.706 km/s.
Geosynchronous satellites, at an altitude of 35,786 km above the equator, requires an orbital velocity of 3.07 km/s.
The Moon, which is around 380,000 km away, has an average orbital velocity of 1.022 km/s.
For comparison, a bullet fired from an AK-47 assault rifle has a muzzle velocity of 0.715 km/s. (Once again, if Wikipedia is to be believed.) Imagine something the size of a bullet colliding with your spacecraft at 10 times that speed — the consequences of an almost-certain uncontrolled depressurization would not be pretty.
The other bad news is that, while nobody really knows if this is a satellite or not, all countries are assuming it has been an attempt to disguise the test of a three-stage intercontinental ballistic missile. One that can easily reach the United States or Russia. And it worked.
The only bit of good news is that the lack of precision that probably led to a spinning satellite is proof of North Koreans’ ineptitude when it comes to design and control these long-range weapons. Putting an ICBM in space is not all you need to, say, drop a couple of nuclear warheads over Los Angeles. You need precision guiding systems for that, something that Kim Jong-Un’s boffins don’t seem to have mastered quite yet.
But then again, a nuclear warhead falling anywhere will definitely be very bad news anyway, no matter how precise it is.
While the rest of the world worries about that, I’m more interested in where the satellite will potentially come down after an almost-certain uncontrolled re-entry. The satellite’s position can be tracked here: rather disturbingly, it passed almost directly over Cape Town as I was typing this post up.
So, lesson of the day — if you’re going to put something in orbit, make sure you do it properly. Otherwise, you are having a bad problem and you will not go to space today.
Yesterday, SpaceX (finally!) managed to get their Falcon 9 rocket off the ground, carrying the Dragon capsule to the International Space Station, and thus filling the void that the retirement of the Space Shuttles has left. Given that SpaceX has a South African expat at the helm, it’s kind of hard not to feel proud about this moment:
Docking with the ISS is scheduled for Friday — given that this is the first docking (or rather, a berthing, as the Dragon capsule can’t dock with the ISS yet), SpaceX will be taking a little while longer than the two days typically taken by the Space Shuttle and Soyuz craft, due to the necessity of having to fully test all systems first. I’ll keep a close eye on when that happens.
For the more geeky readers, SpaceX has put out a press kit (PDF warning) with all sorts of juicy details regarding mission objectives, schedule, specifications, and so forth. Definitely worth the read if you’re into that kind of thing.
NASA’s Lunar Reconnaissance Orbiter (which is on a mission to, amongst other things, map the moon’s surface as a precursor to future manned missions) was recently moved into a orbit of 25 km above the moon’s surface. One of the things that the orbiter did while in that orbit was to take the following image of the Apollo 17 landing site:
More information (and more images) are over at the NASA press release here.