On a recent episode of The Late Show with Stephen Colbert, Dr. Neil deGrasse Tyson said:

And to this day NASA will still report the power of rockets in horsepower, which is completely absurd, because no matter how many horses you string together, they will not elevate into space.So it just doesn’t make any sense!

Question: Is it true? Does NASA still report the power of rockets in horsepower?

Is this in press briefings, or educational material, or scientific literature?

cued at 04:35:

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    $\begingroup$ Why not, it's a unit of power people are familiar with. They use other absurd units such as inches and lbf $\endgroup$
    – user20636
    Mar 7, 2020 at 12:11
  • $\begingroup$ @JCRM I suppose because power is not a useful unit for launch vehicles. The question here is about does or doesn't, not should or shouldn't. $\endgroup$
    – uhoh
    Mar 7, 2020 at 13:04
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    $\begingroup$ It (or power/weight) is useful to get a feeling of just how much energy is being processed by such a small device. $\endgroup$
    – ikrase
    Mar 7, 2020 at 22:54
  • $\begingroup$ follow-up: How did NASA calculate 22 million “rocket horsepower” for the SLS Booster? $\endgroup$
    – uhoh
    Mar 8, 2020 at 23:17
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    $\begingroup$ Maybe this question can be rephrased to "does NDGT use humor as a rhetorical device?". $\endgroup$ Mar 9, 2020 at 12:45

2 Answers 2


Yes, part of NASA's function is public communication. As such they will use units such as "Aircraft Carriers" "School Buses" and "horsepower"

While not precise, expressing thrust in terms of horsepower notionally allows people to understand it more.

"What's impressive about this test is when ignited, the booster will be operating at about 3.6 million pounds of thrust, or 22 million horsepower," said Alex Priskos, manager of the SLS Boosters Office at Marshall. "This test firing is critical to enable validation of our design."

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    $\begingroup$ Yes, for PR purposes only. $\endgroup$ Mar 7, 2020 at 14:05
  • $\begingroup$ I've just asked How does NASA calculate "rocket horsepower"? $\endgroup$
    – uhoh
    Mar 7, 2020 at 14:44
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    $\begingroup$ The content of the links is unimportant (all three mention horsepower) They're merely recent examples. If they do disappear, that may mean the answer has changed. $\endgroup$
    – user20636
    Mar 7, 2020 at 14:45
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    $\begingroup$ It shouldn't be necessary for each reader to go off-site three times to get the answer to the question. Link-only answers are always discouraged in SE and actively discouraged here in Space SE. It's a long-standing policy. $\endgroup$
    – uhoh
    Mar 7, 2020 at 14:49
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    $\begingroup$ There's a video of an airline pilot who's quite into technical things related to cars and planes, in which he calculates how many horsepowers a F-14 Tomcat has -> youtube.com/watch?v=JC-7wRmMH2g While computing horsepower for a jet plane is fun and bogus, it allows an average human to grasp to difference jet power makes when compared to propeller driven planes. So, horsepowers of a rocket may be bonkers, but it's a concept everyday people are familiar with. How powerful is the Saturn V? Very. How much? Very much. Horsepower may be a good crutch to convey the meaning of "Very much" $\endgroup$
    – Dohn Joe
    May 12 at 8:37

Using the inappropriate unit horsepower for rocket engines has a very long tradition. When the V2 A4 rocket of WWII was presented to ignorant NSDAP government officials by the Wernher von Braun team, the only useful comparative value was horsepower known from automotive engines. A thrust value using forth units was not understood.

One offical had the very stupid idea of using rocket engines for railway locomotives.

  • 1
    $\begingroup$ It does make one wonder about "government officials". Some things never change, irrespective of time or the politics of "government officials". Some "government officials" around the world think Covid-19 is fake, others that coal still has a future as an energy source, not to mention other misconceived ideas. If horse power is all their little uneducated or inexperienced minds can understand, talk to them about horse power. They hold the purse strings & "someone" needs finance. $\endgroup$
    – Fred
    May 11 at 17:53
  • $\begingroup$ Sandia Nation labs rocket rail test system $\endgroup$ May 11 at 18:48
  • $\begingroup$ This is a great anecdote. Do you have a source? A quick Google didn't find anything. $\endgroup$
    – paulmrest
    May 11 at 19:31
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    $\begingroup$ I remember reading about that in a book some decades ago. I have to search about 5 books in my book shelf. $\endgroup$
    – Uwe
    May 11 at 19:37

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