Author Topic: Orion Discussion Thread 2  (Read 244817 times)

Offline Overwatchfan123

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Re: Orion Discussion Thread 2
« Reply #660 on: 09/14/2022 08:54 pm »
If Orion has no power, oxygen, or communications with Mission Control, then how the bloody hell can it support a crew?
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Offline John Santos

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Re: Orion Discussion Thread 2
« Reply #661 on: 09/14/2022 09:02 pm »
If Orion has no power, oxygen, or communications with Mission Control, then how the bloody hell can it support a crew?
Because ALL of those services are provided by the ESM, which MUST be jettisoned before EDL.  The power, oxygen and other life support in the Command Module are only sufficient for an hour or so and the comms are only for a range of a few hundred miles, not interplanetary distances.

Sheesh!

Offline Overwatchfan123

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Re: Orion Discussion Thread 2
« Reply #662 on: 09/14/2022 09:04 pm »
OK, OK, sheesh!
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Offline John Santos

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Re: Orion Discussion Thread 2
« Reply #663 on: 09/14/2022 09:09 pm »
The Martian atmosphere is 100 times thinner than Earth’s.  And although there was a brief period when a hard surface landing with airbags was considered for Orion, it must now land in a body of liquid water, of which there is none on Mars.  Orion would go splat trying to land Mars.

The thinness of the Martian atmosphere requires different EDL techniques, namely retropulsion (this is what Starship will use) or deployable aerosurfaces like ballutes and decelerators.  An ablative heat shield like Orion, Shuttle, and the Apollo CM used alone is not enough for Mars.
Minor nit: The Shuttle heat shield was not ablative.  At least, not intentionally.  (Often some bits of some tiles would erode away during reentry and those tiles would have to be replaced before the next flight.)  But this doesn't affect your otherwise correct assertion at all.

Re: Orion Discussion Thread 2
« Reply #664 on: 09/14/2022 09:14 pm »
So I was going on the published images for "Orion" from the NASA and ESA documents which showed combined crew capsule and service module. I guess what you are saying - Capsule has no power, cooling, etc, and of course only the crew capsule would make it to the surface - service module burns up. And to other points, Orion Capsule needs to land in water and couldn't slow its descent enough to land on the surface. Looks like both Orion Capsule and SpaceX Dragon would need significant upgrades to make it to the surface and meet any temporary habitat requirements. Thanks.

Offline Jim

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Re: Orion Discussion Thread 2
« Reply #665 on: 09/14/2022 10:47 pm »
And to other points, Orion Capsule needs to land in water and couldn't slow its descent enough to land on the surface.

Starliner lands on dirt and it couldn't be used.

The parachutes can only slow to a few hundred miles an hour in Mars atmosphere.

Offline Jim

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Re: Orion Discussion Thread 2
« Reply #666 on: 09/14/2022 10:49 pm »
....... Orion Capsule ...........would need significant upgrades to make it to the surface and meet any temporary habitat requirements. Thanks.


Regardless, it is poor shape factor and not enough volume for a habitat, especially one that need to be exited in an EVA suit.

Re: Orion Discussion Thread 2
« Reply #667 on: 09/15/2022 01:12 pm »
Heading back to "Will there be a Starship heading to Mars in 2024" thread. Many thanks to the Orion Tread, I learned a lot. It would seem that we are conspicuously missing a crewed vehicle that can land on Mars - except for Starship perhaps - yet to be proven. In all the good observations and discussion, it did occur to me that there is one fully qualified vehicle that has a proven track record of providing soft landings on Mars - Sky Crane! Maybe there's an angle there for that technology to step into the gap? Good luck with Orion and Gateway Programs.

Offline VSECOTSPE

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Re: Orion Discussion Thread 2
« Reply #668 on: 09/15/2022 02:39 pm »

Perseverance used Skycrane because it was so much heavier compared to prior Mars rovers and because it needed to safely drive away from its landing site, unlike the Viking missions.  The retrorockets needed to decelerate a one-ton payload like Perserverance the last couple hundred miles per hour could have kicked up debris that would have damaged Perserverance and/or dug holes that Perseverance could not drive out of or around.  Putting those retrorockets above Perseverance on Skycrane avoided those mission risks for the rover.

Starship, at least the lunar version, also places its retrorockets for final descent high on the vehicle to avoid debris damage and surface excavation issues.  So the fundamental technique employed by Skycrane is already in use on one human lander.

Skycrane or the high retrorockets on Lunar Starship only address the final EDL leg — shedding the last couple hundred miles per hour of vehicle velocity.  Skycrane or high retrorockets do nothing to get around the thin Martian atmosphere.  That requires hyper/supersonic retropropulsion at much higher speeds and altitudes and with much larger rockets, which Falcon 9 booster recovery has proven out in spades on Earth, or it requires deployable decelerators, like the inflatable ballutes that NASA’s technology program has been slowly developing/testing.  Skycrane doesn’t provide Orion with a way around those challenges.

Even if a big Skycrane did allow an Orion-like capsule to slow down enough for a safe Mars landing, as others have pointed out upthread, capsules lack the right volumes for donning suits, ingress/egress, etc.  Moreover, they have no propulsion system capable of leaving the surface of Mars.  They would be a one-way ticket.

This is an example of a modern, non-Starship approach to manned Mars lander design:

https://ntrs.nasa.gov/api/citations/20160004402/downloads/20160004402.pdf

Orion is for transiting the Earth’s atmosphere.  The lander in that paper, Starship, or variations on them, are what you need for transiting the Martian atmosphere.

Offline Jim

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Re: Orion Discussion Thread 2
« Reply #669 on: 09/15/2022 02:53 pm »
Heading back to "Will there be a Starship heading to Mars in 2024" thread. Many thanks to the Orion Tread, I learned a lot. It would seem that we are conspicuously missing a crewed vehicle that can land on Mars - except for Starship perhaps - yet to be proven. In all the good observations and discussion, it did occur to me that there is one fully qualified vehicle that has a proven track record of providing soft landings on Mars - Sky Crane! Maybe there's an angle there for that technology to step into the gap? Good luck with Orion and Gateway Programs.

Skycrane is a method and not a device.

Offline Jim

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Re: Orion Discussion Thread 2
« Reply #670 on: 09/15/2022 02:56 pm »
Heading back to "Will there be a Starship heading to Mars in 2024" thread. Many thanks to the Orion Tread, I learned a lot. It would seem that we are conspicuously missing a crewed vehicle that can land on Mars - except for Starship perhaps - yet to be proven. In all the good observations and discussion, it did occur to me that there is one fully qualified vehicle that has a proven track record of providing soft landings on Mars - Sky Crane! Maybe there's an angle there for that technology to step into the gap? Good luck with Orion and Gateway Programs.

No.   Starship is the lander and the habitat.  Orion is not going to be any better or further along.   It has no room to store consumables.
« Last Edit: 09/15/2022 02:57 pm by Jim »

Re: Orion Discussion Thread 2
« Reply #671 on: 09/20/2022 02:19 pm »
Heading back to "Will there be a Starship heading to Mars in 2024" thread. Many thanks to the Orion Tread, I learned a lot. It would seem that we are conspicuously missing a crewed vehicle that can land on Mars - except for Starship perhaps - yet to be proven. In all the good observations and discussion, it did occur to me that there is one fully qualified vehicle that has a proven track record of providing soft landings on Mars - Sky Crane! Maybe there's an angle there for that technology to step into the gap? Good luck with Orion and Gateway Programs.

Skycrane is a method and not a device.
Interesting - so a few last questions, do you think all the 'smarts' for Skycrane were in the Rovers? In other words, Skycrane didn't have any nav, sensing, landing guidance, communications, etc - Rovers had it all? Where could the design details for the Skycrane be found? Who built the Skycrane? Thx.

Offline Jim

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Re: Orion Discussion Thread 2
« Reply #672 on: 09/20/2022 02:45 pm »
Heading back to "Will there be a Starship heading to Mars in 2024" thread. Many thanks to the Orion Tread, I learned a lot. It would seem that we are conspicuously missing a crewed vehicle that can land on Mars - except for Starship perhaps - yet to be proven. In all the good observations and discussion, it did occur to me that there is one fully qualified vehicle that has a proven track record of providing soft landings on Mars - Sky Crane! Maybe there's an angle there for that technology to step into the gap? Good luck with Orion and Gateway Programs.

Skycrane is a method and not a device.
Interesting - so a few last questions, do you think all the 'smarts' for Skycrane were in the Rovers? In other words, Skycrane didn't have any nav, sensing, landing guidance, communications, etc - Rovers had it all? Where could the design details for the Skycrane be found? Who built the Skycrane? Thx.

Again, there is no such thing as a "skycrane"
The descent stage, which performs the skycrane maneuver, has minimal avionics.  Most are in the rover.  The descent stage has the landing radar, antennas and an IMU but the computer in the rover with its INU does all the work.  The radio is also in the rover.  The descent stage has a controller to allow it to fly away.    JPL built the descent stage.  Detail can be found in press kits and paper submitted.  There are no drawings or plans available on the internet.

Re: Orion Discussion Thread 2
« Reply #673 on: 09/20/2022 08:04 pm »
Jim, thanks for the help. I realize that you are speaking technically when you say "there is no such thing as a skycrane", but understand that if you Search the Internet, it is full of articles that contain the term skycrane and even articles about skycrane. So, please don't shoot the messenger. Thx.

 

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