NASA’s Curiosity rover lands on Mars

A recent comment on UKMA’s Facebook page has prompted Metric Views to look into NASA’s latest mission to Mars. This is reported to have landed at 06:32 BST on Monday 6 August.

Frank Davidson wrote the following on Sunday on the UKMA Facebook page:

“I’ve been watching NASA streams recently ahead of the Mars landing (anticipated
2012-08-06 05:31 hours zulu). There has been a mix of imperial and metric used in the press conference (but hopefully not in the lander and rover).”
So what is Curiosity, what is its purpose, and how come it has so far escaped the fate of the Mars Climate Orbiter of 1999, which was lost because of a measurement muddle?

NASA’s web site is largely metric, with English/USC in brackets:

This looks promising, and the story from the BBC’s science correspondent is also entirely metric:

However the account on the BBC one o’clock news was Imperial. I wonder what happened there. Do the two parts of the organisation not communicate?

And the purpose of the mission? A BBC Horizon programme broadcast on 30 July 2012 suggested it would look for evidence of life on Mars.

9 thoughts on “NASA’s Curiosity rover lands on Mars”

  1. Hi all,
    Curiosity is an impressive piece of technology. I looked at the JPL site and the above links. The weight of Curiosity is stated as 899 kg at the JPL site and 900 kg in the science environment article. I am not sure which is the more accurate mass. I think NASA chose to use SI units in expressing flight data and distance even though Curiosity may have been built to US Customary units. This in itself is a turning point. I also think the news media is more comfortable using SI units because of the proximity to the Olympic Games, where the public has been exposed to metres and kilograms.


  2. Gene Mechtly reports as follows from the USA:

    “The NASA-JPL Control Room Conversations and News Conference Reporting of the Mars Landing on the NASA Channel … was almost exclusively SI early this morning for performance data; distances in meters or kilometers, speeds in meters per second, remaining fuel in kilograms etc. (except for pressure in psia).

    It was a disappointment to see graphical simulations of entry into the Mars Atmosphere in mph.

    I believe, without proof yet in hand, that most of the hardware was engineered in millimeters.”


  3. Our friends in the US have been able to supply further information:

    “I did some further research and even though there is no definitive yes or no considering Curiosity’s measurement origins, the evidence points to SI.

    Consider this link:

    and note the responses and subsequent links. NASA’s factsheet ( on curiosity is dual, but SI is primary and rounded.

    This link: appears to be the Jet Propulsion Laboratory of NASA where it was built and tested. Note only metric is used and numbers are rounded.

    I can’t speak for certain, but I believe JPL is the only division of NASA that actually uses metric. They were responsible for the first Mars Orbiter that crashed in 1999. Then they did everything in metric, but they also contracted some of the design to Martin-Marietta, who went against the contact and provided thrust data in pounds instead of newtons.

    So if I were to conclude, it does appear that Curiosity is a metric child. It is unfortunate that other parts of NASA and the media go to great lengths to hide this fact.

    One final note. I think it is a real hoot that the person who originally asked the questioned mentioned 10 feet, but all of the responses came back metric only.”


  4. @ Bob

    Semantics. Lockheed and Martin Marietta merged in 1995, several facilities got new names. But it was a former Martin Marietta lab. I don’t think it is worth playing what was their name on the day the error was made. There were numerous faults. They failed to follow the contract, and both NASA’s and the supplier’s quality systems failed to detect the error. In my opinion, NASA took an overly large share of the blame because their quality system failed to detect it. Again, in my opinion, there was inadequate attention to how the supplier’s personnel were unaware of the terms of the contract and/or ignored those terms and structured their program to provide wrong data, as well as how their quality system missed it. Adherence to contract requirements usually gets considerable attention. I can understand a subtle error, but not “cluelessness” relative to requirements. Good project control is about capturing the requirements, then figuring out how to meet them, and doing so with evidence.


  5. The purpose of this mission is more important that it may seem and, as an interested observer, am very pleased to see it has landed successfully.

    Scientists don’t know for certain exactly how life got started here on Earth although they do have some pretty good ideas. I think what they are really looking for is a concrete example of it having occurred elsewhere, even if it never developed beyond primitive microbes. It would be confirmation that current theories are along the right lines.

    If they do find it, the implications will be quite profound. It would show without doubt that given the right basic conditions life is inevitable. And that would mean the wider universe must be teeming with it.


  6. Well, do not Americans still have that pesky little phrase in their code of laws about the prefered system being SI?


  7. @Ian
    Yes we do. However, I might describe it as a toothless phrase. Look at all the metrication it has caused since 1988. Although the word “voluntary” was omitted from the 1988 amendment, no action was ever taken to require metrication, and the Metric Board which occupies many paragraphs, even though it had no power and only coordinated, had already been defunded and disbanded.

    The only positive action ever taken by Congress to demonstrate this “preferred” status was the requirement for dual indication of net contents under the FPLA, passed in 1992, in force in 1994. Although Congress required Federal agencies to do business and particularly Federal construction in metric, it then checked the powers of those same agencies when they took their charter too seriously. Circa 1995/96, Congress forbade FHWA to force metric road construction or metric highway signs on the States, road contractors, etc. A once good metrication plan was completely overturned in the course of a few years. Federal building designers were forced to consider Customary-dimensioned bricks and lighting fixtures in their design if lower priced. Coupled with “Buy American” initiatives, you can guess how that turned out.

    While metric is indeed preferred, Congress has at least equalled if not surpassed the UK government in demonstrating lack of direction, plan, focus, and commitment in bringing their fine words to life and actually causing any metrication whatsoever. It would be redundant to say they speak with forked tongue because they are politicians, and the joke goes,
    “How do you know when a politician is lying?”
    “His lips are moving.”

    A few agencies have been punished for being too metric (well, too forceful about being metric), and no agency has ever been punished for not be metric enough. NASA has repeatedly sought waivers to metric requirements in their programs and they have never been officially gigged for this behavior.


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