Disturbing the Universe

David L Clements, science and science fiction

Death in Orbit

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There was great, and largely justified, worry about the recent satellite launch by North Korea. After all, if they can launch a washing machine sized satellite into orbit, they can, in principle, land something not much smaller anywhere on the planet.

But the North Korean military, who are used to total secrecy, are now discovering that when you put something into orbit, everyone can see you mistakes. Because it seems that their brand new satellite is probably dead.

As anybody who has been involved with space projects learns very quickly, getting a payload into orbit is only half the job. And even that isn’t easy, because launching a rocket essentially involves making sure that many tonnes of high explosives explode in just the right sequence. Any deviations from that sequence and the launch vehicle is going to end up becoming a very big, and very expensive, firework, with all the consequences that implies*.

But getting the launch vehicle to work isn’t everything.

First of all, if it’s a multiple stage rocket, you have several other large explosions that have to be properly controlled before you get where you want to go. Then, even if you get to Earth orbit successfully, your satellite has to separate from the rocket so that it can operate properly and avoid early re-entry and death. The Glory satellite is a recent casualty to this failure mode, as its launch fairing failed to separate.

All of these factors mean that the stress of launch for those involved goes on a lot longer than the initial moments of fire and steam as the rocket leaves the launch pad. You can read something of my experience of this at the Planck and Herschel launch in my piece in the Rocket Science anthology (please buy a copy!).

And then, even if all of the transportation aspects work, your satellite has to have survived the experience. Your satellite is likely to be a precision engineered piece of scientific equipment, but the experience of a rocket launch will have given it a far more vigorous and extended shake than any airline baggage handler or package shipper can manage**. You will hopefully have taken precautions, have tested your flight hardware on a shaking table that simulates launch, but the real thing is always different, and you can’t make repairs afterwards. Even in the best case scenario you’re going to have to make some changes to settings and calibrations to account of the on-orbit realities – this is why most satellite missions have a significant amount of time allocated to ‘on orbit checkout’ before operations can begin. And it’s a this point that the North Koreans seem to have come unstuck, very publicly. Because there are legions of people who watch what is happening in orbit – not just military and security people, but a large contingent of amateurs who report their results to the public. Examples of such space watchers have included staff and pupils from Kettering Grammar School and many others, now linked by the internet into a powerful, public, space surveillance operation, with reports collected by people such as my friend and colleague Jonathan McDowell***.

Observations by these people across the electromagnetic spectrum have found problems with North Korea’s satellite. Radio data indicates that it is not transmitting anything at all, and certainly not the Songs of Gen. Kim Il-sung and Gen. Kim Jong-il as intended. Secondly, optical observations show a regular variation in the amount of light the satellite is reflecting, suggesting that the craft, which needs full stabilisation to carry out its earth observation mission, is tumbling out of control. Taken together, these suggest that, while the launch was a success, the satellite died.

This can’t be hushed up, as past North Korean failures have been, since the satellite is up there for the whole world to see.

So where does this leave us with respect to the military implications of this launch?

Assuming that they have nuclear warheads, for use in military applications of this vehicle, and North Korean nuclear tests have produced only small yields (a few kilotons at best) and a curious lack of radionucleides, a weaponised launcher would still need to get a working ‘physics package’ and a working re-entry vehicle into orbit for it to be a serious threat. The performance of the current launch suggests that they have a long way to go before they can achieve either of those aims with any reliability and repeatability.

However, the prospect of North Korea lobbing what would at least be dirty bombs, full of radioactive material, in approximately random directions because their guidance fails, is not something that appeals. But this isn’t the great nuclear deterrent that the generals of North Korea are looking for.

I wouldn’t want to be a North Korean rocket scientist this week.

* When Ariane 501 exploded on launch, I literally saw a friend’s scientific career end.

** And shippers and baggage handlers have killed quite a few instruments in the past!

*** Who I hope to tempt to the science programme of LonCon3 in 2014


Author: davecl

Astronomy, science, science fiction

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