|
Author
|
Topic: Lunar regolith reaching the Apollo CM orbit?
|
Buel
Member Posts: 870
From: UK
Registered: Mar 2012
|
posted 04-22-2023 02:16 PM
   
I’ve been in communication with someone who is adamant that the "cloud generated by the Apollo lander crossed the command module orbit."I’m finding this very hard to believe being as the CM orbit was roughly 70-80 miles? |
Headshot
Member Posts: 1210
From: Vancouver, WA, USA
Registered: Feb 2012
|
posted 04-22-2023 05:55 PM
Starting with Apollo 14, I believe, the CSM's perilune was around 10 mi (50,000 feet) for a short time. NASA used the SPS engine to lower the CSM/LM's orbit for a few revolutions to provide extra fuel for the LM's "hovering time" during the landing phase. This practice was supposed to start with Apollo 13, but that did not happen. |
Buel
Member Posts: 870
From: UK
Registered: Mar 2012
|
posted 04-22-2023 06:08 PM
Thanks for that. However, I’ve been reading how the regolith actually affected the CSM? Quote here; [The regolith] can effectively drag the orbital systems, increasing the energy required for station keeping, not to mention that going through a mist of sand particles of 10 microns at orbital speeds can have a noticeable sandblasting effect.The effect is similar to the challenges we face in the design of satellites in very low earth orbit, where the effects of the drag are very noticeable. |
Headshot
Member Posts: 1210
From: Vancouver, WA, USA
Registered: Feb 2012
|
posted 04-22-2023 06:19 PM
I would suspect that the amount of regolith that actually made it up to 50,000 feet above the lunar surface would be inconsequential at best. Also, the particles would most likely have been on ballistic trajectories, and thus short-lived, with very few actually going into some sort of lunar orbit. |
SpaceAholic
Member Posts: 5240
From: Sierra Vista, Arizona
Registered: Nov 1999
|
posted 04-22-2023 07:14 PM
quote:
Originally posted by Buel:
I’m finding this very hard to believe being as the CM orbit was roughly 70-80 miles?
Exhaust velocities of typical bi-propellant liquid rocket engines can well exceed 6000 MPH; this is sufficient to eject lunar surface material into orbit (escape velocity approximately 5000 MPH). |
Henry Heatherbank
Member Posts: 309
From: Adelaide, South Australia
Registered: Apr 2005
|
posted 04-23-2023 05:27 AM
Coincidentally I saw a comment to a similar effect on social media in Australia today, and simply didn’t believe it. I cannot see how the LM engines (descent or ascent) could have been powerful enough to disturb surface regolith so that it ascended to CSM orbital altitude. |
Buel
Member Posts: 870
From: UK
Registered: Mar 2012
|
posted 04-23-2023 05:45 AM
I’m with you but what are your thoughts on this; Dust Transport And Its Effects Due To Landing Spacecraft Lunar lander engine exhaust blows dust, soil, gravel, and rocks at high velocity and will damage surrounding hardware such as lunar outposts, mining operations, or historic sites unless the ejecta are properly mitigated. Twenty years of research have developed a consistent picture of the physics of rocket exhaust blowing lunar soil, but significant gaps exist. No currently-available modeling method can fully predict the effects. However, the basics are understood well enough to begin designing countermeasures. The chap on LinkedIn also posted this; Managing the Plume Effect To Assure Sustainability Of Lunar Activities. |
oly
Member Posts: 1446
From: Perth, Western Australia
Registered: Apr 2015
|
posted 04-24-2023 10:44 PM
quote:
Originally posted by Buel:
No currently-available modeling method can fully predict the effects.
The math required to make these predictions exists, as does the imagination and creativity to come up with a range of solutions. Without an additional external force acting upon the debris, the projectiles will travel in the opposite direction from the force acting upon it.When designing a significant lunar base, some type of barrier could be used to protect a lunar base from rocket plume debris. This may be done by assembling the base inside a crater that has a profile suitable to act as protection from high-velocity debris. Computer modeling can replicate the path of debris if the force of lunar gravity is known, the force of the rocket exhaust is known, and the expected mass of debris is know. Given two of these are required to design a vehicle capable of landing on the Moon and the third we have a reasonable amount of information known. This would give engineers a good idea what is needed to protect a lunar base. Some type of earth-moving equipment could be used to construct a barrier, or you could build the base behind a large rock, or obsolete hardware could be used as a shield. Engineers could design a lunar base that could land autonomously to begin with and the crew land away from the base and relocate by foot or rover. I don't believe this is an insurmountable deal breaker, just a problem in need of a solution. |
advertisement