Feb. 9, 2022
5:15 a.m. PST

Minimum Separation Velocity and Jettison Operations

Hi again, Shane! I'm sorry if I am pestering you with questions at this point but what is the minimum separation velocity of the jettisoned trash? Is it really 100m/s (360km/hr) as stated in ICES-2021 or can it be lower than that "almost impossible speed" (it would take 250000J of kinetic energy to jettison a 50kg trash)?

Also, it was mentioned that the jettison frequency would only be at every 7.3 days (Therefore accumulating trash mass and volume). During the time of operation, are the astronauts only allowed to do it once or do it multiple times (divide the 50kg trash into manageable parts)?

ps. I apologize if I am asking way too many things. I only want to provide the right solutions for the problem. Thanks! (again).
6 Replies

Shane Jenkins HeroX team
Feb. 14, 2022
8:46 a.m. PST
Hi there Ross, no worries. The Sponsor mentioned that a more relevant, but not completely confirmed, estimation for the separation velocity is about 0.4 meters/second or more.

As for your second question, I believe that can be somewhat flexible with your discretion. Obviously holding onto waste longer affects the range of the spacecraft and can crowd the interior, but jettisoning less frequently could also mean that less air is lost from an air lock. All of these variable are for you to consider, but the rate mentioned in the guidelines was meant to help guide you as a fairly standard prediction.

Hope that helps!

Feb. 14, 2022
8:48 a.m. PST
That really helps a lot! Thank you very much, Shane!

Carlos Daniel Aguilar
March 3, 2022
12:57 a.m. PST
Hola me llamo Carlos y me ha servido mucho vuestro diálogo. Soy aficionado al espacio y no se de cálculos, Alguien sabe si la velocidad de escape necesaria varia mucho o poco si se aplica desde la exclusa o si se aplica a dos metros fuera de la nave?.

March 3, 2022
1:32 a.m. PST
Hi, Carlos! No, not really. I don't see any reason for it to affect the velocity. It doesn't really matter if you launch it inside or outside the airlock unless you're worried about friction on the airlock walls. As for gravity, the spacecraft would be way too small to have any significant effect on your projectile. Hope that helps!

Carlos Daniel Aguilar
March 3, 2022
1:44 a.m. PST
Gracias Ross...!! imaginaba que la velocidad y el peso de la nave pudieron ejercer alguna fuerza de inercia en el sentido de la trayectoria.

March 3, 2022
1:54 a.m. PST
That's a fair assumption, Carlos, but since the projectile originated from the spacecraft, the projectile would therefore have no relative velocity (before jettison) as it was originally traveling with the spacecraft. Remember that "Speed is Relative". About the weight of the spacecraft. I don't see any reason that could possibly affect your projectile's velocity, well unless the ship is under acceleration.

Happy to help, Carlos!
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