Deriving the Dimensions of the Rodrigues Debris

Though the piece of debris discovered on Rodrigues Island has not yet been definitively linked to MH370, the distinctive pattern applied to one of its sides seems to match perfectly the interior of a Malaysia Airlines 777, as Don Thompson has so astutely pointed out. Therefore, pending confirmation from the authorities, it seems highly likely that this represents the fourth piece of MH370 debris to be recovered from the Indian Ocean since the start of the year.

The first three pieces have been studied in Australia and handed over to the Malaysians. Apart from confirmation that the two Mozambique pieces almost certainly did come from MH370, no further information about them has been released, and it seems unlikely that any will be before Malaysia issues its final report, which is slated to take place after Australia calls off the seabed search in the middle of this year. Therefore anything we are going to learn from these pieces is going to come from studying photographs and videos taken before they were ushered away into official secrecy.

In today’s post I’d like to discuss my attempts to determine the exact size of the Rodrigues debris fragment, and what its dimensions tell us about the size of the marine organisms growing on it. This is important in determining how long the piece floated in the ocean.

 

1- side view

Figure 1

 

In Figure 1 we are looking at the top of the piece, with the “back” of it (the part not facing toward the cabin interior) upward. I’ve marked in blue 12 inches on the ruler visible in the foreground. Based on the relative number of pixels, I calculate the length of the edge in yellow to be 11.5 inches, and the thickness of the piece (red line) as approximately 1 inch. The purple circle shows the approximate location of the “Lonely Barnacle” which I’ll talk about in a little bit.

In Figure 2 we see a close-up of the bottom edge of the piece. Although the object appears to be of uniform width, the hex cells at the bottom have a different orientation from those elsewhere in the piece: their longitudinal axes are vertically oriented, rather than back-to-front:

2- bottom view copy

Figure 2

 

In a comment on an earlier post, reader Ken Goodwin identified the honeycomb material as most likely being 1/8 inch 3 lb Nomex. This would match well with the width of the piece as measured in Figure 1. If the seven cells I’ve outlined in blue above have a total length of 7/8 of an inch, then the total width of the honeycomb portion (green line) is 0.8 inches.

Figure 3 shows the Lonely Barnacle mentioned above. Based on the hex cells it is lying next to, its length appears to be almost exactly 1 inch, or about 25 mm. (Note that what we’re measuring here is the length of the capitulum, in other words the shell.)

3- lonely barnacle small

Figure 3

 

Note that the barnacle might not be lying exactly flat; if its main axis is skewed in relation to the camera its actual size will be somewhat longer, perhaps 26 to 28 mm.

In Figure 2 it’s possible to see that quite a lot of barnacles are growing in area where the surface has become separated from the honeycomb in the inboard portion of piece (the right-hand side in Figure 1). Unfortunately, I’ve been unable to find any good pictures of this area. The best images showing barnacles are of an area at the top of the front of the panel, on the outboard side:

5- vertical

Figure 4

 

4- barnacle farm

Figure 5

 

Based on their apparent size in these images, the largest barnacles appear to be, again, approximately 25 mm in length.

I ran these images past Cynthia Venn of Bloomsburg University, who is perhaps the most knowledgeable person in the world about Lepas growth rates. She identified these barnacles as being Lepas anatifera, with some smaller Lepas anserifera perhaps thrown in as well. She was unable to determine whether the anatifera belonged to the subspecies striata (which reach a maximum length of 35 to 40 mm) or anatifera (which can reach up to 50 to 60mm) but at any rate they are significantly smaller than their maximum size, which they usually reach in six months to a year.

Of their observed length, Venn told me: “They can get that size in a couple of months.”

Note, too, that most of the barnacles that are visible are substantially smaller than the largest ones; if the piece had been floating in the ocean for two years, we would expect a large community of full-sized barnacles, as is seen on tsunami debris of comparable age. Note, too, that the barnacles on the Rodrigues piece are significantly smaller than those on the Réunion piece, the largest of which measured 39 mm.

It is difficult to explain how a piece that has been adrift for two years can have substantially smaller barnacles than another piece that has been floating in the same stretch of ocean–experiencing, that is, the same temperatures and nutrient levels–for only 1.25 years.