NASA is observing galaxies billions of light years away in search for Dark Matter. To be honest, they could easily point their telescopes to the nearest prison to observe dark matter.
Is this a joke about a lot of people of color being in jail?
Yes, I think that this is more important than them. They are too uneducated
This is a very narrow view of incarcerated people of color and I urge you to educate yourself on why the majority of people in jail are people of color. Regardless this is an insensitive joke and you shouldn't say it.