4 ms·

What I don't understand is how we still don't know where the damn thing is going to land. We know where it's at, we know its velocity, and we know its altitude.

What I don't understand is how we still don't know where the damn thing is going to land. We know where it's at, we know its velocity, and we know its altitude. And yet nobody seems to be able to calculate the math for the its de-orbital trajectory? Is our rocket science after all these years really that much of a joke?

mulmen 5y ago
It’s out of control. The atmosphere is not uniform.
- t0mbstone 5y ago
  And there are no simulations that can at least figure out a rough landing area?
  - mulmen 5y ago
    That is what this website [1] does. Simulating global weather from the surface up to the Thermosphere [2] a week in advance with the required fidelity to notify even continents would be an enormous undertaking. It would require detailed models of solar activity including how it reaches Earth. As we get closer to reentry time the estimates will improve because there are fewer variables. This particular case is notable because it is a deliberate uncontrolled reentry. Typically reentry is controlled, allowing for fine adjustments. Launch profiles typically also have some safety margin built in where even if a controlled launch becomes uncontrolled the spacecraft will still end up somewhere safe. None of that is the case here so the impact point is at the mercy of the wind. [1]: https://aerospace.org/reentries/cz-5b-rocket-body-id-48275 https://aerospace.org/reentries/cz-5b-rocket-body-id-48275 [2]: https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Thermosphere https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Thermosphe...
    - mulmen 5y ago
      It’s too late to edit but I attempted to reference my own comment and realized this link has already rotted. It now redirects to a useless Twitter thread. See https://orbit.ing-now.com/satellite/48275/2021-035b/cz-5b/ https://orbit.ing-now.com/satellite/48275/2021-035b/cz-5b/ for an up-to-date estimate. Unfortunately it doesn’t have the nice visualization aerospace.org has decided to revoke for this mission specifically.

mulmen 5y ago

It’s out of control. The atmosphere is not uniform.

t0mbstone 5y ago
And there are no simulations that can at least figure out a rough landing area?
- mulmen 5y ago
  That is what this website [1] does. Simulating global weather from the surface up to the Thermosphere [2] a week in advance with the required fidelity to notify even continents would be an enormous undertaking. It would require detailed models of solar activity including how it reaches Earth. As we get closer to reentry time the estimates will improve because there are fewer variables. This particular case is notable because it is a deliberate uncontrolled reentry. Typically reentry is controlled, allowing for fine adjustments. Launch profiles typically also have some safety margin built in where even if a controlled launch becomes uncontrolled the spacecraft will still end up somewhere safe. None of that is the case here so the impact point is at the mercy of the wind. [1]: https://aerospace.org/reentries/cz-5b-rocket-body-id-48275 https://aerospace.org/reentries/cz-5b-rocket-body-id-48275 [2]: https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Thermosphere https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Thermosphe...
  - mulmen 5y ago
    It’s too late to edit but I attempted to reference my own comment and realized this link has already rotted. It now redirects to a useless Twitter thread. See https://orbit.ing-now.com/satellite/48275/2021-035b/cz-5b/ https://orbit.ing-now.com/satellite/48275/2021-035b/cz-5b/ for an up-to-date estimate. Unfortunately it doesn’t have the nice visualization aerospace.org has decided to revoke for this mission specifically.