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Last month, while hanging out with Minute Physics, Smarter Every Day and 3BLUE1Brown
at Vidcon we started exploring the possibility that there are parts of World War 1 era German
Warships flying to the edge of our Solar System aboard the Voyager Satellite.
It was a pretty fascinating story, but none of us could confirm whether it was true.
I became a little obsessed with idea and wanted to share my journey to uncover whether there
is any truth to the story.
So first of all, why would there be parts of German Warships used in satellites at all?
When it comes to creating sensitive sensors, like geiger counters, it is vital that they
are constructed from materials with minimal radioactivity, after all Geiger Counters are
designed to detect and measure radioactivity and if the materials they are made from are
producing radiation, then their readings will be inaccurate.
Any steel produced after the Trinity Test, the world’s first nuclear detonation in
1945, is contaminated with radionuclides like Cobalt-60.
After this first test there has been 2,000 nuclear tests, many of them above ground,
that have elevated the world’s background radiation to a peak of 0.15 milli sievert
per year above natural levels in 1963.
This contamination get’s introduced to the steel though the refining process, which I
spoke about in more detail in my History of Iron and Steel video, as air is pumped through
molten pig iron to oxidise the excess carbon and impurities, allowing them to be removed.
As this occurs the contaminated air deposits the cobalt-60 in the iron and thus elevates
it’s radioactivity.
It is possible to use pure oxygen in this process in a clean room environment, but it’s
expensive.
A much cheaper source of low-background steel is from warships that sunk prior to these
first nuclear tests, the most famous source being the scuttled German fleet of battleships
in the Scapa Flow, Scotland.
Following the surrender of Germany in World War 1 the German army was instructed to hand
over all of their U-Boats to the Allied forces, however an agreement for the fate of the German
surface fleet could not be found and it was decided that they would be moored with a skeleton
crew of sailors until peace negotiations had finalised.
But, one June 21st 1919, the German Admiral Ludwig von Reuter (Ludvig von Royter) decided
to take matters into his own hands.
Signalling his men to scuttle the ships and thus prevent them from being used by the Allies.
52 of the 74 battleships moored in Scapa Flow sunk.
The cost of salvaging these ships was deemed too expensive at the time, as there was a
glut of scrap metal following the war.
The first of the scuttled ships were raised in 1923 to clear shipping routes and a further
38 ships were raised and scrapped until the outbreak of World War 2.
The remaining 7 ships have had small scale salvage operations to recover the low-background
steel that has been shielded from background radiation under 47 metres of water.
These ships are now protected Ancient Monuments and Archaeological Areas Act and you can actually
explore the wrecks with a diving permit.
So are there parts of steel from these wrecks on the Voyager 1?
This is a claim that has been circling on the internet for quite some time, but I could
source no proof for it.
So I started to investigate further to see if there was any possibility that parts of
Voyager 1 would need this steel.
The first thing to note is that steel will be used only when it absolutely needs to,
as it’s heavy.
Lighter materials like aluminium and titanium are much more common.
So I began scouring the internet for construction details, and I found this fantastic document
released by NASA in 1980 detailing the construction of Voyager 1.
There were no radiation sensors included in the list of sensors, which was the first strike
to the likelihood of this story.
Next I searched for references to steel, and on page 7 I found that the shielding for the
radioisotope thermoelectric generators were constructed from a steel alloy and gold foil,
but the radioisotope thermoelectric generator itself is powered by radiation, it would have
no need for low-background steel.
The support boom was built from steel and titanium, but for the same reasons it is highly
unlikely that these parts would have any use for low-background steel.
These were the only references for steel I could find.
So it is HIGHLY unlikely that there is any material from these ships aboard the Voyager
1, but there is a more likely scenario that they may have been used in Explorer 1.
The Explorer 1 was the first satellite ever launched by the US.
Launching aboard a Jupiter C rocket in 1958, 20 years before Voyager, it did include radiation
sensors on board, as it’s primary mission objective was to investigate radiation levels
in space and evaluate whether a human could survive a space mission.
The instrument section of the satellite was skinned with steel, which could well have
been low-background steel.
Explorer 1 oddly found a much lower cosmic ray level than expected, which Dr James Van
Allen theorised being caused by the sensor becoming saturated by a very high radiation
region around earth caused by charged particles from solar wind becoming trapped in earth’s
magnetic field.
This belt was later confirmed and named the Van Allen Belt.
So there is a small chance that steel from these old German Warships made it to space,
but short of speaking directly with the engineers that designed the Explorer 1, it’s next
to impossible to confirm the source of their steel.
Thankfully the need to salvage this low-background steel from old warships is diminishing, thanks
to treaties bringing an end the testing of nuclear weapons and the short half-life of
radioactive isotopes like Cobalt-60, which has a half-life of 5.26 years.
Background radiation has fallen dramatically from the highs of 1863, falling all the way
from 0.15 millisieverts per year to 0.005 mSv/yr above natural levels.
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