Tag Archives: H2 Rocket


If it was a rocket fairing, why didn’t it burn up on re-entry?

H2As soon as my last article was put online, someone asked me, “If it’s space debris, surely it would have burnt up upon re-entry. I mean it’s a payload fairing right?”

People’s perception of atmospheric re-entry involves a lot of heat, such as this rendition of an Apollo capsule enduring a hot re-entry. (Source: NASA)

Yes, it’s a payload fairing, and it’s designed to protect the payload (satellites, etc) on their way up through the atmosphere. Now we’ve know all about heat upon re-entry, so why didn’t it burn up? The simpe answer is:


Orbital vehicles travel at enormous speeds. They do this in order to stay in orbit and use their momentum to not be pulled back down to earth by gravity. The International Space Station is at a low earth orbit of 400 kilometers (above earth surface) and travelling at about 7.66 kilometers per second (or 27,700 kilometers/hour). At geostationary orbits (at 35,786 kilometers above earth surface), satellites travel at around  3.1 km/s. The H2 rocket payload fairings come off at about 201 kilometers above the earth’s surface, just after it escapes the atmosphere. Orbital speed at around 200 kilometers is just under 7.8 km/s.

The usual H2 rocket trajecotry and stages. (Source: JAXA)

The rocket’s speed at 201km is very much less than the orbital speed, when the payload fairings come off. Why do the payload fairings come off so early? You don’t want to carry any weight you don’t need! Orbital launchers are expensive business. The payload fairings’ sole purpose is to protect the payload from the atmosphere. Once you’re out of the atmosphere, you don’t need the fairing anymore and, poof, bye-bye fairing.

The fairing is ejected at very low orbital speed, and the fairing would simply fall back to earth. Given it’s very low speed, it won’t have the super hot plasma-inducing friction heat like we see on common orbital re-entry. The fairings themselves would simply create drag by it’s own shape keeping its speed slow as they come down. There would still be damage from sonic shockwaves (speed of sound is very slow up there), and eventually aerodynamic stress joins the fray and break the fairing into several pieces.

Given the H2 rocket launch trajectory above, the location of the fairing ejection would stiill be very close to Japan. From there, it’s a matter of where it landed precisely and what were the predominant oceanic currents head.

There seems to be quite a bit of payload fairings found from various rockets over the years. A lot of the Arianne rocket payload fairings have been found drifting in the Atlantic, or even landing in the jungle.

Here’s one example:

Payload fairing of the Arianne Alphasat launch found in the Brazilian jungle. (Source: AFP/BBC)

There has a lot of these being reported over the years. If you’re interested to find out more on these, I strongly suggest you read Paul D. Maley’s Space Debris page (click to go there). I was amazed at how much have come down and reported from these launches over the years. I’m glad someone kept track of some if not all of them.


OK, it’s not MH370, or part of a ship but maybe the H-IIA or H-IIB rocket instead

I wrote earlier about the piece of debris found off Thailand that was suspected to being a part of MH370 and how I think of it’s unlikelihood. I also wrote that I’d love to be wrong about it, and I am extremely happy to say that I’m wrong. It doesn’t seem to be a part of a ship’s superstructure as I mentioned in that article.

As I went to bed last night, others were tweeting away about other alternatives. If MH370 is like the past haunting me, this episode is no exception.

Jon Ostrower of WSJ tweeted:

Now, several years ago at one of my previous employer, we were looking to launch a satellite (the project has been cancelled since though). We entered into discussions with Mitsubishi Heavy Industries and was offered to launch our satellite using the H-IIA/B which I will refer to as H2A and H2B instead) family rocket. That, like Inmarsat, was in my past, but MH370 seems to keep haunting me with my past, but that’s a story for another time.

While Jon pointed out the debris is from the H-IIA (H2A) rocket, I would like to point out a key dissimilarity.

The H2A shown by Jon has a straight cylindrical fairing:

Cylindrical payload fairing typical that of the H2A rocket

The debris found on the coast, is not a straight cylinder:

Debris found on the Thai coast

You can immediately see that the radius of the curved rim on top is NOT the same as the one at the bottom. The radius on the top is larger than the one at the bottom!

But WAIT! Before you dismiss this as “not from the H2A rocket”, I want you to have a look at the H2A and H2B rocket family, to see what variants are available:

H-II, H-IIA, H-IIB family rockets. (Source: Ofuku)

As we can see, there are some fairings available that can be larger than the neck of the rocket, and that is not limited to the H2B. The H2A variant shown above is the H2A202. Have a look at the H2A204 below:

The various versions of H2A rocket on offer to the market. (Source: Ofuku)

The H2A204 is a 2-stage  rocket that weighs 445 tons, and is able to carry a 6 ton payload to the Geostationary Transfer Orbit and is offered with the flush 4/4D-LC payload fairing, or the 5S payload fairing. The H2B is a 2-stage rocket that weighs 531 tons, and is able to carry an 8 ton payload to the Geostationary Transfer Orbit and usually uses a 5S-H fairing which is longer than the 5S.

Both the H2A and the H2B can carry the wide payload fairing, which is made by Kawasaki:

Available payload fairings for the H2A and H2B made by Kawasaki. (Source: Kawasaki)

So, it seems that it’s one of the 5S fairings from either an H2A204 or H2B.

Some of those who read my previous article would probably now like to ask some questions:

1 – What about the wires seen on the debris?


Well, we can see here:

5S-H fairing prior to final assembly. (Source: JAXA)

You can see the cable there at the bottom, and see that there are not that many pieces of wiring on the fairing.

2 – What about protrusions you mentioned?


These protrusions can be found on the latches used on the H2 5S series fairings. Zoom on the photo below to see:

Fully assembled S5-H fairing prior to mating with the rest of the rocket. (Source: JAXA)

3 – What the panels numbered 307 and 308 each with the 6 bolts, and the other numbers?

Panels 307 and 308 and other station numbers, along with the big protrusions

We can see that panels 307 and 308 are located quite close to a doubler with fasteners. We can see a similar arrangement of the panels, writings and protrusions here below:

The completed S5-H fairing mated with the rocket. (Source: JAXA)

The photo from the debris found above is likely to come from the other side of the circle from the photo above. See the photo of the fairing prior to the assembly, and the arrangement of the 2 round panels along with the fairing edge and protrusions.

How I see this is that it is pretty conclusive that the debris found is not from MH370, although we can’t say which rocket it came from, that’s for the Japanese to decide.

Now, I guess some of you will be asking, “Hang on, the Japanese don’t launch rockets often!” Well, Mitsubishi has been actively marketing the H2 family rocket since 2012, trying to capitalize on some of the failed launches of the Russian Proton launchers. They’ve grabbed one pure commercial launche since then in addition to the Japanese’s own and international space programs. Here’s a list of H2A launches since March 2014:

  • F24 – H2A202: 24 May 2014, multiple small Japanese satellites
  • F25 – H2A202: 07 Oct 2014, Himawari 8 weather satellite
  • F26 – H2A202: 03 Dec 2014, multiple small Japanese satellites
  • F27 – H2A202: 01 Feb 2015, intelligence payload
  • F28 – H2A202: 26 Mar 2015, intelligence payload
  • F29 – H2A204: 24 Nov 2015, Telstar 12 Vantage (Telesat)

For H2B launches since March 2014:

F05 – H2B: 19 Aug 2015, Cubesats & H2 ISS Transfer Vehicle

Back to the original point again, I’m very happy that I was wrong in guessing that this piece is from a ship’s superstructure, because it is more likely to have come from either H2A-F29 or H2B-F05 rockets. Now this could explain why there are less barnacles attached to it than people expected. But one thing is for sure, this is NOT from MH370!

If you’re curious on why the payload fairing didn’t burn up upon re-entry, read my next article (click here).