Rocket Carrying North Korean Spy Satellite Crashes into Sea | Hacker News Reader

Rocket Carrying North Korean Spy Satellite Crashes into Sea

gizmodo.com

99 pointsnickthegreek72 comments

I keep telling people: Space is hard.

> The rocket lost thrust after the first stage separation due to an “abnormal startup of the engine” on the vehicle’s second stage that may have been caused by an instability in the engine and fuel system, according to KCNA.

This is the challenge for most newcomers to space deal with. Every space startup in the US over the last couple years seems to have all had some trouble between stage 1 engine cut off and stage 2 operating. It's so easy in Kerbal Space Program!

You need to: Stop your main engine; disconnect the first and second stage cleanly, successfully; put at least a little distance between first and second stage; Start the stage 2 engine in a vacuum and in freefall (which you cannot test out on the ground) and do it remotely/autonomously; have stage 2 correctly identify its own position and speed well enough to aim to the stable orbit you hoped for.

Oh, and don't forget to successfully ditch your faring at some point or the satellite is trapped in an egg shell with no solar panels, communications equipment, or (in the case of a spy satellite) telescopes.

It was hard enough with two Estes engines! Often that second stage went off into the wild blue, never to be seen again, at some weird angle, or even spinning!

LOL. Me and my friends designed a two stage rocket, and of course we insisted that our first attempt use "D" size engines. The first stage took the rocket up about 75-100 ft and when the second stage lit off, the rocket somehow kicked over and was flying perfectly horizontal.

The problem was, we were launching from the bottom of a retention basin at the local park district so we started out at -40 ft altitude. This meant the rocket went zooming across the neighborhood only slightly above tree top level.

Oh that is just brilliant. Model rocket shenanigans were a highlight of my childhood.

Turns out, duct taping extra motors onto the rocket body as a cluster of second stage engines, initiated by cannon fuse itself ignited by the first stage didn't work so hot.

I had a few model rockets, but I also made some completely custom ones out of index cards wrapped around a small motor. I added curved fins so one would spin. THAT was interesting! One of my (normal estes) rockets was hanging from a tree over a bike path by the park for like a week until I finally brought a ladder and some poles to get it down. Honestly I'm surprised nobody ever tried to grab it lol.

Edit: The very first estes rocket was from a kit - our teacher had a "rocket week" and we all made and launched rockets. Mine went up, a fin fell off, then it u-turned, and then went straight for the math teacher.

yeah, the problem is if they don't ignite at exactly the same time, you'll get unbalanced thrust and wild spinning! lots of excitement there!

Well, if your goal was to create an anti-ship cruise missile, I'd say you're about half-way there..!

https://en.wikipedia.org/wiki/File:Brahmos_ER.webm

in the high power rocketry the newer flight controllers that have staging capabilities have lockouts now. We can configure logic like "only fire the second stage igniter if N seconds have elapsed since stage 1 burnout AND the rocket is traveling at a min of X ft/sec AND no more than Y degrees off vertical". It makes things a lot safer and more convenient

1) an M motor igniting 45 degrees off vertical 20k feet up means a long drive let alone a long walk.

2) an M motor igniting at a negative velocity ( descending and likely pointing down) is very scary heh.

A year back or so I built a thrust vectored model rocket with two stages using an Estes E12 and an F15 motor for the second stage. The flight computer had logic in it to only light the second stage if the first stage had been successful to lift off the ground and the rocket at some vertical angle plus/minus some degrees and the velocity was positive upwards and non-zero. Luckily this first attempt worked out!

https://www.youtube.com/watch?v=zPtFv-cwcfQ

The first stage was designed to be pushed out by the second stage and a bit before the first stage was completely out or the rocket would lose too much control authority.

We had Christmas paper tubes, balsa fins cut with a dull xacto knife, a hand carved nose cone and a super glued washer as a thrust ring.

That sounds about right :P There's some really cool stuff nowadays, but I certainly didn't grow up with it!

A buddy & I noticed that 1/4A and 1/2A engines only have a bit of propellant, all at the bottom. So we hacksawed off the empty part to get a rocket body less than 2" long. Glued on some fins and a paper nose cone. It went up about two feet and then tilted and zoomed off sideways. Enlightening.

So YOU were the ones that started that fire in October Sky

Well, my grandfathers surname was Hickman, and I was born in WV.

(I know, Homer Hickam is different...but it's close)

Met him once in college, I was in the Corps of Cadets at Virginia Tech, which is where Homer Hickam ended up as well. Very humble guy, at least in the few minutes I was around him.

Fun fact, while at VT he led the creation of the original Skipper cannon. He and a bunch of other cadets thought it was shameful that VT had no cannon and VMI would trot out this little deck gun ("it was really more like a mortar!" according to him) at football games and shoot it off. He amassed a bunch of brass uniform bits and approached a foundry in IIRC Radford about it. They laughed about how a cannon made of uniform brass would blow up, but traded them for gunmetal brass.

The first time they fired it was a salute for President Kennedy, but the assassination happened before they had time to drill a touch hole. They rounded up every ketchup squeeze bottle they could find, put the charge of powder in that, and taped a piece of fuse in the spout. The ketchup bottle assemblies were lit and slid down the barrel.

Years later, a bunch of drunk cadets on Skipper Crew blew the original up. They kept cramming charges down after misfires, I think they had three in there when it went. The explosion blew up the caisson and threw shrapel, some of which embedded in Slusher Tower and is supposedly still there. The pieces were gathered up, mostly reassembled, and at least when I was there resided in the Corps Museum.

Anyway, yeah, rockets!

My favorite Hickam story is the ultimate "Do you know who I am?"

"And I am on the National Space Council that oversees NASA,"

https://www.usatoday.com/story/news/nation-now/2018/08/22/na...

Same latin root

Nah I grew up in a different part of southern WV...and a few decades too late to be responsible!

In grad school I took a class from Robert Boyer and J Strother Moore (famous for Boyer-Moore string searching and the 2005 ACM Software System Award for the Boyer-Moore Theorem Prover). It was a long time ago, but I remember an anecdote that Boyer explained happened while working at NASA on the Apollo project. It is a good example of the simple things that can go wrong in space. (I hope I can explain it clearly and correctly, I took that class decades ago.)

At one point, to return to earth the command module must separate from the landing module (after it has been on the surface of the moon and back) and fire the thrusters that will return the astronauts and some moon rocks to earth. The astronauts flip some switches to start this sequence.

Shortly before the whole Apollo moon mission, programmers discovered a bug. The thruster doesn't know where the center of gravity of the orbiter is located, but it must adjust its gimbals so that the thrust is in line with the craft's center of gravity to prevent tumbling the spaceship. This is automatically done, rapidly at the startup of the thrusters, by firing and then wiggling the nozzle a bit to figure out the correct direction vector in line with the center of gravity by readings from gyros. It seems like this should work.

The bug is that there would be a delay between flipping the switch to fire the thrusters and the actual firing because, in zero-gravity, the fuel is just a big floating ball of liquid in the fuel tanks and consequently there is a delay of a few seconds while little maneuvering gas jets start accelerating the craft causing the fuel to move to the back of the tank (where the fuel lines are) and finally making its way into the nozzle of the trusters where it ignites automatically. Unfortunately, the software assumed that the thruster would ignite right away, and would wiggle the nozzle and get a completely wrong answer for the calculated center of gravity because the engine wasn't ignited yet. Then, with the nozzle pointed in the totally wrong direction, ignition would cause the craft to be pitched into a dangerous tumble while trying to leave lunar orbit. This bug wouldn't be obvious during testing on earth because the fuel would be at the bottom of the tank and ready to fire without the delay.

It was too late to patch the software so some instructions were taped next to the switches instructing the astronauts to put in the necessary delay manually.

In this vein, I highly recommend the RP-1 mod set for KSP1, which introduces (among other things) ullage and engine start failures, launching from a realistic Earth. Really gave me a huge appreciation for the difficulty of achieving orbit.

https://github.com/KSP-RO/RP-0

> [RP-1] Really gave me a huge appreciation for the difficulty of achieving orbit.

One of my favorite things about (even un-modded) KSP was appreciating -- even on a super simplified level -- all that went into making things go into space. Even just launching in the same direction as the orbit of the planet to get a gravity assist seems so "duh" now but was something I had never considered before KSP.

What a great game, will have to check out RP-1.

I believe you can start the second engine without stopping the first engine, then initiate separation and cut fuel to the first stage engines. A number of rockets feature this design and have a way for the rocket exhaust gas to pass to the outside of the hull before separation occurs.

Yep, its called hot staging & was used on some of the Titans for example.

Another even more conservative option is to ground start all your engines and then throw some of them away directly (original Atlas) or with a stage (R7/Soyuz).

There are certainly some tradeoffs with this, such as making it impossible to use a proper altitude/vacuum optimized nozzle if all your engines are ground started.

The old Soviet Vostok did something similar with the third stage, AFAIK.

Never mind the whole magic trick of landing the first stage on a barge and catching the faring in a big net.

They actually just scoop em out of the ocean instead of catching the fairings now

The recovery of the shuttles SRBs was always really cool to me. They float and the process even included manipulating their buoyancy to get them upright for easier recovery!

M/V FreedomStar and M/V LibertyStar were the recovery vessels. I named my sailboat the S/V FreedomStar in namesake. Out of Cape Canaveral, FL.

some people think the goal of kerbel space program is to launch rockets into space ... i think its to have them fail in hilarious fashion. we are not the same.

Atlas 1 and Space Shuttle hacked this by having all engines started on the pad.

Space shuttle still needed to restart their engines in space so that they could slow down enough to return to earth.

Those are other engines, much smaller and using different propellants.

It really is rocket science.

I've seen a lot of reporting, including this, which states that this is North Korea's "first" spy satellite. I thought it was well known that NK has performed at least 2 successful satellite launches previously, KMS-3-2 and KMS-4, which are documented on Wikipedia and tracked on n2yo.com. Does anybody understand the disconnect between the reporting and the evidence of 2 existing spy satellites?

Officially, those were non-spy Earth observation satellites. Not that that means much, but this one is actually labeled a spy satellite. Besides that, KMS-3-2 is known to have gotten to orbit while failing to stabilize and KMS-4 is not known to have sent any signals back.

Good points, according to the Wiki page, KMS-4 was initially tumbling and then shown to have stabilized, which seems to indicate that communication was established.

Not necessarily, at least in terms of communications back https://space.skyrocket.de/doc_sdat/kwangmyongsong-4.htm. Of course, it's also possible nobody has publicly tried looking at the right time. At the same time, it's also possible it wasn't really a functioning imaging satellite in the first place and was more just another test. Hard to tell when the official source just says whatever sounds most interesting that day.

Plot twist - it was a spy submarine all along

   Even before the rocket crashed into the sea, its launch was deemed controversial due to an international ban on North Korea from using ballistic missile technology

The takeaway from this is that the international community is concerned that N Korea is developing ballistic missile technology under the guise of an orbital vehicle. The difference between orbit and sub-orbital flight is only a bit of Delta V and different payload.

You used the word "only" there to imply ... well, that it's simple? I don't think most serious aerospace folks would agree with that assessment.

The word "only" is appropriate here. If you have an ICBM it's still a challenge to get to orbit. If you have a rocket capable of getting to orbit you automatically have an ICBM. If you've got the power to get to orbit you've got the power for a ballistic trajectory.

The bigger challenge is to get out of orbit into one piece. Heat shields for the transonic regime are not trivial technology.

Heat shields are not trivial but they're achievable with 1950s era technology. If you pay the mass penalty you can just use a big "dumb" ablative heat shield. With a bomb you don't need to build anything too sophisticated, it only needs to work once and you don't want it back.

With a rocket capable of getting a meaningful payload to LEO you've got the power to pay that mass penalty if the trajectory is ballistic.

None of this is "easy" but it comes along with developing orbital capabilities. This is why Sputnik's launch was such a big deal to defense planners. If the Soviet Union could get a little satellite into a stable LEO it could deliver a warhead to the continental US.

Or possibly to build a FOBS (or even put nukes in orbit outright).

Well, sure, it's not that simple, but the main point here is that it's "easier" to hit any point on the surface of the Earth with a rocket than it is to get a payload into orbit.

Nothing is simple in aerospace, and I'm sure there are things I'm missing. But generally speaking, an orbital vehicle becomes suborbital when it doesn't have enough speed to not fall back to the Earth. There's re-entry to contend with, but that's a solvable issue. And then there's the payload, also solvable.

What's it doing crashing off of the west coast of Korea? If you're trying for orbit, don't you usually launch east, so that you get a boost from earth's rotation? Or did the rocket just malfunction that badly? (Or is the article just wrong on that detail? Or did I read it wrong?)

Spy satellites are launched to highly inclined orbits (think passing over the poles) so they can cover the whole of the Earth and slightly against the Earth's rotation so they can be sun-synchronous[0]. So this is just what you would expect from such a satellite.

[0] https://en.wikipedia.org/wiki/Sun-synchronous_orbit

A guess would be to avoid Japanese airspace, who promised to shoot down anything flying overhead. That assumes this rocket was actually intended to reach orbit and deposit a real satellite.

It seems very ambitious to try to park a satellite in orbit on your very first orbital rocket. Unless I'm missing something?

They put their first satellite in orbit in 2012 confirmed by NORAD. This is not the first launch of a satellite, only a "spy satellite."

Honestly, feels like a concerted media effort to stoke panic about North Korea. Japan and South Korea acted like they didn't know was happening publicly (alarms etc) despite being informed of the launch publicly days before as reported in the media.

> Japan and South Korea acted like they didn't know was happening publicly (alarms etc) despite being informed of the launch publicly days before as reported in the media.

They may have known it was happening, but once the launch malfunctioned, they didn't know where it was going.

And I don't think either side trusts the other when they say "we're launching a rocket near you but not at you".

Not to mention, they have to trust that they're actually telling the truth because it's basically an ICBM with a satellite as a payload (instead of an explosive weapon). Heck, it could still be both. Since it's a hostile party launching it, they have to treat it as if it's a weapon before it even launches (such as warning they'll shoot it down if it's in their airspace).

They've gotten a couple sats to orbit. https://en.wikipedia.org/wiki/Unha

For some high inclination orbits (like if you want a polar orbit that covers the whole world) it might make sense to launch in a NNW or SSW direction. Even for lower inclinations, sometimes it's easier for geopolitical reasons. IIRC Israel always launches retrograde over the sea to avoid upsetting their neighbors, could be similar with NK

>If you're trying for orbit, don't you usually launch east, so that you get a boost from earth's rotation?

No, or rather it's somewhat more complicated. Yes there are many popular orbits (or deep space) where that's an advantage, but there are also lots of orbits where it's less so or even outright undesirable such as with polar orbits. Depending on the purpose of the launch in question it may be necessary to cancel out that energy which means it's actively more expensive to have it. Locations far from the equator get less either way and have to take that into account.

Launch safety is critical too as well, nobody wants to have debris from a failed launch come down somewhere undesirable. For civilized countries that's anywhere that might cause damage, but even for dictatorships it'd include other countries they don't want to offend that specific way or alternatively to give insights into whatever they are launching that could come from wreckage analysis (failure in low first stage isn't going to mean stuff burns up like a deorbit). So even when a target orbit would indeed benefit from such a directly easterly launch, a dog leg is often part of it.

Obviously NK is less than transparent about all this but the basic incentives are still there.

>For civilized countries that's anywhere that might cause damage

Trying to find a joke for that applied to SpaceX/Starship.

Their launch complex is in the far west of the country, and directly east does cross over portions of Korea Bay(/Yellow Sea). Or, I guess, they could have been going for a polar orbit.

39.65974870373334, 124.70613853508173

It was launched from Tonghae which is in the east right?

Tonghae is in the far east, but per the article it was launched from Sohae Satellite Launching Ground.

Oh strange, in the news here it said Tonghae-Ri. Thanks!

Edit: Aha I see it, I looked it up and it says it is from Tongchang-ri which is where Sohae is, not Tonghae. This was what confused me.

Little knowledge + too much wikipedia + assumptions = fake news :P

nah, fake news wouldn't have printed the correction and just doubled down on it

I'm amazed they admitted it! Not even claiming it was 'shot down' or denying completely that there ever was a spy satellite, just straight up admitting that it didn't work.

for internal drpk propaganda, it would be fairly difficult to keep the launch failure from the public, when success is orbit.

the best spin on a failure is partial success. to their population, dprk has one job, to protect the population from the imperialists. losing the rocket to military action which they have been claiming they have successfully been keeping at Bay is a worse internal spin than 2nd stage failure

Fun fact: a wartime-like siren rang in Seoul for 1min, freaking out everybody, until it was announced that it was a false alert.

(I wasn't there but I saw people panicking on Kakao Talk group chats)

> The rocket lost thrust

At my age I completely understand that issue

How fast will this be torn apart? I wonder what level of technology, sourcing of components, and quality of security there is.

It's most likely already 'torn apart' by the impact and possibly explosion. A lot of parts will have sunk to the seafloor. And any analysis might be classified.

Also I'm sure they are able to obtain components from the west, their border with China is pretty porous.

But yeah I'm also interested to hear the outcome in case something does surface. Just wouldn't count on it.

It said it simply lost thrust and descended, I don't think it exploded.

Surprise.

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