Pound-inch units finally give way to metric in space

It looks as if astronauts, cosmonauts, or yuhangyuan as we will soon learn to call them, will before long have to cope with only one measurement system in space as the US winds down its programme and China takes its place.

The Guardian reported on 29 September 2011 about the shift of leadership in space that is now taking place:


Michael Griffin, professor of mechanical and aerospace engineering at the University of Alabama in Huntsville, has raised concerns about a new space race and called China, which wants to put a robot on the Moon in 2013 and build its own space station for 2015, “a near-peer competitor”. He has also said “When the Chinese can reach the Moon and we cannot, I do not see why any other nation would regard us as a world leader” .

A muddle of measurement units in space hardware was inevitable when the US responded to the successful launch of Sputnik 1 by the Russians on 4 October 1957. But it seems as if this period is now drawing to a close.

This was not at all what the barons had in mind when they wrote in Magna Carta in 1215  “let there be one measure”. Nor is it a giant leap for mankind, perhaps just a small step in the world’s changeover to SI.  But would-be British astronauts can at last dispose of their Whitworth/ISO inch spanners.

8 thoughts on “Pound-inch units finally give way to metric in space”

  1. To be fair, NASA should be designing and procuring in metric according to Federal law (all Federal agencies are supposed to). Unfortunately, the law has enough loopholes to drive a truck through, and NASA whines and cries that the design is part carry-over and metric would be really difficult, and it needs to use customary, and gets an exception approved. Thus starts another Customary design cycle.

    I suppose the publicity is good for a country’s image, but exactly what did we get out of going to the moon or the ISS? We spend a lot of money, but the only space efforts that produce any results are satellites and unmanned missions. There’s not much point in going to the moon just to go to the moon again, and while people talk up the plan, it seems to lack specifics for what do we get out of it.


  2. Few people could doubt the value of satellite technology nowadays. I wonder though how many people saw the potential back in 1957 when Sputnik was launched?


  3. I truly believe that the era of America in space is over. It is really just a matter of time before NASA is completely put out of business. The US simply can not afford to keep it going. I also believe that in the future any deep space projects will have to be done by countries working together in joint ventures. No one country, no matter how rich they are today can afford to go it alone. And working together means using the same measurement system. That being metric.

    It seems though that even NASA back in 2007 conceded that any future exploration by them in space will be metric:


    John mentions the ISS. I remember at the time it was being designed that NASA defended its decision to design its portion in inches. It claimed it had already started the design using inches and a change to metric would be too costly. So presently the American portion uses inch fasteners and the other portions use metric.

    Talk about deliberately creating a muddle, especially in outer space.

    The Europeans and the Russians are also planning a joint venture for the exploration of mars:


    The American inch-designed Constellation project, had to be cancelled because it was too costly.

    I believe that eventually the Chinese, Russians, EU and possibly others will join forces in exploring space. It is the only way it can be done. If the Americans ever swallow their pride, they too may be a part of it.

    Wikipedia states that the ISS will end its service around 2020 and Russia’s next space station OPSEK, will be separated in 2020 to form a new, separate space station, supporting deep space exploration.



  4. But what is going on back here on earth??
    We have just bought a trampoline from Kanga for our grandson. All dimensions of this trampoline (8ft x 12ft) in imperial only including information regarding usage in the instruction manual.
    This appears to be an Australian product, probably manufactured in China. So who decided that metric measures were not appropriate and why?
    At least the nuts and u-bolts were metric and a metric spanner was supplied!!


  5. Any chance the trampoline was originally intended for the USA market? If as a result the supplier printed up the instructions in Imperial only, then maybe the retailers in the UK might have decided they could go ahead and sell it there as well with no complaints.


  6. @Ezra, Martin

    We certainly see a lot of good LIKE that in the US. Chinese goods are commonly really metric, tools included, but translated into Customary. I Googled the brand. It turned up registered to a Chinese company on Alibaba. It also appears to only be sold in the UK. On the company’s webpage, the specs were all metric (thickness of the steel frame, data on the springs, etc) except overall dimensions.

    My “50 inch” Chinese patio table is clearly 1.30 m if not 1.300 m (just over 51″) so don’t expect great precision in the conversion. It came with all metric hardware and a metric Allen wrench for assembly. My patio is large enough that I enjoy the extra, unadvertised inch, but in a small room, it could be a problem.


  7. Actually on the subject of “Pound Inches in Space” (eh, what?), I’m not sure that the USA is finished in space just yet. And I suspect pounds and inches will be back soon enough. Regardless of what NASA want to do, they have the problem that they don’t (and never did) actually build any space hardware. Rocket design and build, and engine design and build and crew capsule (or “ship”) design and build is contracted out to US aeronautics companies. People like Boeing and McDonnell Douglas and (er well, you know, the usual suspects).

    The US aviation industry is locked into engineering things in USC by dint of its own complexity and the fear of mistakes (i.e. deaths) if they dare change.

    I can’t see how US space technology can break free of that, even if it wanted to. From this side of the pond, it looks like NASA’s brief foray into metric was only done to keep the government happy and to “look modern”. Since the loss of the Mars Orbiter due to a contractor’s cockup, I feel NASA are less inclined to keep going on that track. I know it was cancelled, but the proposed “Constellation” rocket project was in USC to “keep costs down” (i.e. avoid more cockups) wasn’t it?

    I’d be pleased to be wrong, but history suggests I won’t be. Not for a long time yet.

    ( It must be costing a fortune for non-US companies like Rolls Royce to be in the aero engine industry as they are. If they build engines for Boeing ‘planes (as they do), they have to be tooled in USC. If they build engines for Airbus (as they do) they have to be tooled in metric. So Rolls Royce must have to be running two parallel engineering and manufacturing plants and be limited by how easily they can transfer staff from one to the other. Anyone know how they cope?? )


  8. Forgive me for digressing here to a subject that is not strictly about metrication but I hope everyone will see at the end that it does have some relevence.

    To return to the subject of space exploration I speak as a life-long fan of manned spaceflight. But seeing how some of it has panned out over the past few decades and the emergence of artificial intelligense I am starting to question it.

    The challenge of manned space exploration is enormous and without a tangible material benefit that is easily recognised by a significant fraction of the world population, it won’t be properly financed or done in the right manner.

    I am dead against any attempt to cut the short-term cost or development timescale of a manned mission to Mars based on a ground launched spaceship, which will necessarly be small, cramped and stressful for its occupants after several months in space, and using throw-away chemical rocket technology.

    If we are going to do it then it should be space launched from Earth orbit or possibly the Moon. Futhermore it should only be attempted after we have returned to the Moon and have had experience in living on its surface with routine travel between the Moon and an Earth orbiting space station (so that the technology for space colonisation is matured in a way that is less risky). Added to this is the necessary development and procurement of a single stage to orbit vehicle (space plane) to get from Earth’s surface to an orbiting station (to facilitate much larger construction projects including a decent interplanetary space-ship which will be able to use a lower thrust propulsion system).

    All this will cost a fortune and it can only be done internationally, spread over a relatively long period of time.

    I don’t think America will necessarily drop out but it will have to take its place on a more equal footing with other nations. In this context the US will have no choice but to ditch USC and fully metricate.


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