gobblox38 t1_jal0lpq wrote on March 2, 2023 at 4:24 AM

Reply to comment by MattC1977 in NASA’s DART data validates kinetic impact as planetary defense method | DART altered the orbit of the asteroid moonlet Dimorphos by 33 minutes by mepper

~~These are arc minutes. There are 360° in a circle, 60 minutes in a degree, and 60 seconds in a minute.~~

On earth, an arc minute along a great circle is equal to a nautical mile. The conversion to any unit of length depends on the radius of the rotation. If the orbit is elliptical, the equation gets more complicated.

EDIT: I was totally incorrect about what they were talking about. See daughter post for details.

TKtommmy t1_jal2jo6 wrote on March 2, 2023 at 4:42 AM

No, we're talking the orbital period in time. Actual minutes of time.

gobblox38 t1_jal5eri wrote on March 2, 2023 at 5:09 AM

>Based on the change in the binary orbit period^2 , we find an instantaneous reduction in Dimorphos’s along-track orbital velocity component of 2.70 ± 0.10 mm s^–1

I should have read the article more closely. I thought they meant the angle changed when what really happened is the speed reduction increased the orbital period by 33 minutes.

After giving some consideration as to why they'd write it like that, it makes sense. Changing the orbital period by an amount of time may be enough for another orbiting body to get out of the way.

My bias got in the way of this one, thanks for the correction.