A thought about Mars and manned missions

Full disclosure...I am not a big fan of the whole manned mission(s) to Mars theme; I strongly question the scientific value of such an endeavor , but that's for another thread. This thread is intended to address some of the difficulties landing on Mars and a possible solution.

Mars is notoriously difficult to land on...successfully. Depending on how you crunch the numbers, upwards of 50% of Mars missions have failed to land successfully. One of the big challenges is the fact that while Mars does have an atmosphere, that atmosphere is very, very, thin. Consequently, you can't really slow a craft down enough using the atmosphere as a brake before you deorbit. (that, and parachutes suck on Mars) We are pretty good at landing on planets with no atmosphere (i.e. the Moon), and we're great at landing on planets with atmosphere like Earth. Mars, not so much.

Now, Elon Musk might not be very good at marketing cars, but SpaceX builds a bang-up rocket in the Falcon 9. It seems to me a Falcon 9 like product could be adapted to landing on Mars. The current evolution of the Falcon 9 isn't really designed for a Mars mission, but something like it could be developed using similar technology.

When people think about SpaceX and Mars many immediately jump to the SpaceX Starship, and that's all fine and good for the "getting there" part, but it doesn't address the "landing on Mars" part. So, why not develop a Falcon 9-like booster stage which would travel along with a Starship like craft? The way I see it, you could kill two birds with one stone here. First, you could overcome the atmospheric challenges of landing on Mars, and second you would land with a booster capable of returning occupants back to orbit upon departure (something rarely discussed in Mars mission discussions).

The Falcon 9 doesn't really use the atmosphere for braking. It basically turns around, fires a retro burn and falls out of the sky (controlled of course) and then fires another retro burn right before touch down. This same concept would seem to be a viable solution for Mars.

What do you think?

a reply to: Flyingclaydisk

There's probably value in having people directly experience Mars. People are very innovative and interactive. There's probably classes of information that can be obtained by direct experience that is beyond information gathered by measurement devices.

I'm sure the NASA mission planners are taking into account cost-benefit analysis for every type of mission.

a reply to: Flyingclaydisk

I really love Mars threads, S&F!

But isn't SpaceX Starship designed exactly for the descend method you're proposing? It will be equipped with raptor engines allowing for vertical landing and take-off on Earth and other planetary bodies.

SpaceX's Starship spacecraft and Super Heavy rocket (collectively referred to as Starship) represent a fully reusable transportation system designed to carry both crew and cargo to Earth orbit, the Moon, Mars and beyond (source).

Just a thought...

a reply to: Flyingclaydisk

Humans going to Mars is a one way trip to an early death.
Months instead of days being hammered by solar radiation.
The low gravity is going to weaken bones and muscles.
No food, no water, lots of dust and sand storms.

Everyone on planet earth will watch these people die a miserable death live on television.


We are not ready for the technical challenges Mars presents..not yet.

Probably most of the problems we have had with landing on Mars is the fact that we're having to design an autonomous landing system that has to do everything itself because of the time delay. And of course we launch it and everything has to be clockwork from launch until it lands. I mean look at the fact that on these missions, we don't even know if the thing landed until after it's happened.

So, I guess ironically, the best argument for sending people to Mars is to make the landing successful. Sending robots sounds like a good idea until you lose enough of them to pay for a manned mission. It's amazing to me that any of the landers we've sent have actually been successful.

I think that likely all the challenges of designing these things to be nearly autonomous AND to last as long as they do with no one there to repair anything could be better spent just doing the human mission. If it's feasible to keep people alive long enough to reach Mars (or make the trip faster) I'm sure they can find people who are willing to risk their lives to go. If they die, they die.

a reply to: Bluntone22

That's why we go underground 😌

Sending in hardened nodes with compound meta materials designed to deflect and block radiation, upon landing, we'll start digging down, reinforcing the tunnel walls with some sort of spray that hardeneds, courtesy of the eggheads at MIT.

Dig deep enough to avoid the Radiation and expand down there.

Space has always been about Speed.

High speed to get into space, high speed to get into orbit once you are in space, high speed to get out of orbit, high speed to get anywhere once you’re in space, and high speed making landing on anything difficult.

Most people think that this is just the way it is because that’s the way it has to be.

WRONG!

There is NO requirement to “blast” into space like a bat out of hell. And, if you can provide adequate shielding from radiation, you can spend years in space with no ill effects: humans have doing it for millennia.

Speed is, in fact, a problem in space travel; it takes “fuel” to achieve speed, and it takes the same amount of “fuel” (here we say “fuel” to mean energy) to slow down once you reach your destination.

And the more fuel need to carry to eventually slow you down, the more fuel you need to to carry to speed you up.

Now, you do need a certain amount of speed to stabilize your orbit, and you need a bit more speed to break out of an orbit to head out into interplanetary space.

But overall, speed is overrated!

The atmospheric density of Mars is about the same as it is on Earth at 100K FT.

We already simple things, like balloons, that can fly at that altitude.

And, so far, Mars is our best (though far from ideal) shot at a “lifeboat” for our species.

a reply to: Bhadhidar

Humans in space don't get exposed to the brunt of the sun's radiation.
The ISS is orbiting inside earth's atmosphere and under the protection of our magnetic field.
We have very little data on solar radiation effects on the human body. The Apollo astronauts reported strange flashes in their eyes if I recall correctly.

Then you still need to deal with the damage zero gravity does to the human body.

You can argue with 60 years of rocket scientists on why we still blast into space.

en.wikipedia.org...

davidson.weizmann.ac.il...

a reply to: Bluntone22

Therefore, if we generate a similar magnetic field around a spacecraft, we should be able to provide a similar level of protection against radiation for its occupants.

Many plans/ideas already exist for doing just this; the current stumbling block is the question of providing enough power for such a shield.

Power means mass, and mass equates to expense.

For the “short hops” into, and through, space man has attempted so far, it just hasn’t been economically feasible to equip, or even test, such shielding ideas.


As to the “60 years” of blasting into space...

Well, some would say that the internal combustion engine, which has been around almost twice as long, has had its day, as well.

New technologies and new materials, not to mention old technologies incorporating new materials might well be pointing in previously overlooked directions.

a reply to: Bhadhidar

Sure sure...
Just that easy..

originally posted by: Flyingclaydisk
Full disclosure...I am not a big fan of the whole manned mission(s) to Mars theme; I strongly question the scientific value of such an endeavor , but that's for another thread. This thread is intended to address some of the difficulties landing on Mars and a possible solution.

Mars is notoriously difficult to land on...successfully. Depending on how you crunch the numbers, upwards of 50% of Mars missions have failed to land successfully. One of the big challenges is the fact that while Mars does have an atmosphere, that atmosphere is very, very, thin. Consequently, you can't really slow a craft down enough using the atmosphere as a brake before you deorbit. (that, and parachutes suck on Mars) We are pretty good at landing on planets with no atmosphere (i.e. the Moon), and we're great at landing on planets with atmosphere like Earth. Mars, not so much.

Now, Elon Musk might not be very good at marketing cars, but SpaceX builds a bang-up rocket in the Falcon 9. It seems to me a Falcon 9 like product could be adapted to landing on Mars. The current evolution of the Falcon 9 isn't really designed for a Mars mission, but something like it could be developed using similar technology.

When people think about SpaceX and Mars many immediately jump to the SpaceX Starship, and that's all fine and good for the "getting there" part, but it doesn't address the "landing on Mars" part. So, why not develop a Falcon 9-like booster stage which would travel along with a Starship like craft? The way I see it, you could kill two birds with one stone here. First, you could overcome the atmospheric challenges of landing on Mars, and second you would land with a booster capable of returning occupants back to orbit upon departure (something rarely discussed in Mars mission discussions).

The Falcon 9 doesn't really use the atmosphere for braking. It basically turns around, fires a retro burn and falls out of the sky (controlled of course) and then fires another retro burn right before touch down. This same concept would seem to be a viable solution for Mars.

What do you think?

Back in 2011, NASA started a couple of studies that went on for a few years and looked at using SpaceX hardware for landing on Mars. I worked on those studies. The concept was called “Red Dragon”, because it was supposed to take a Dragon capsule of the type used to transport astronauts to Low Earth Orbit (a “Blue Dragon”) and look at whether it could actually land on Mars. Here is a pointer to the Wikipedia article on the concept:

en.wikipedia.org...

From that background, I would like to comment on your OP.

First, the statement that “you can’t really slow a craft down enough” using Mars’ atmosphere is not really correct. All Mars missions that have gone to the surface have used Mars’ atmosphere to slow down one way or another. What is true is that the type of aerodynamic deceleration you use will be different, depending on the size of the craft that you are trying to get to the surface.

The process of getting a craft that is entering Mars’ atmosphere slowed down and planted on the surface is referred to as Entry, Descent, and Landing (EDL). As the name implies, there are 3 different phases to the process. The entry phase is where the craft comes into the top of the atmosphere (typically, at ≈ 6 km/s) and begins slowing down using aerodynamic drag. In the simplest case, that process is completely passive; the entry vehicle is stable like a shuttlecock and it simply slows down and falls down to lower altitudes (it’s called a ballistic entry). Typically, a ballistic entry at Mars will enter the top of the atmosphere at about 250 km and travel maybe 150 km downrange before it reaches its terminal velocity which is usually below about Mach 2. Below Mach 2, a parachute can be deployed which begins the descent phase. That slows the vertical speed even further, until the landing phase can begin. The Viking landers Jettisoned the descent parachute and used rocket engines to perform the final (soft) touchdown. All US Mars missions from that time on stayed on the parachute all the way to the ground and used airbags to cushion the final impact, up until the Mars Science Lander (MSL) mission of 2011.

When the entry vehicle gets big enough, you can no longer use a purely ballistic entry, you have to start using aerodynamic lift. The MSL mission did that; it entered the atmosphere with a slight positive angle of attack which generated some lift. That allowed the vehicle to actually fly downrange much farther than previous missions. That allowed the vehicle to spend more time down in the thicker part of the atmosphere where it had time to slow down enough to deploy the parachute. Like the Viking landers, the MSL lander used rocket thrusters to zero out its vertical sink rate. (Unlike, any other lander, however, MSL introduced the Sky Crane idea to lower the rover to the ground from hover).

The Red Dragon would have been 3 or 4 times heavier than MSL, and would have to have used lift even more aggressively during entry phase. The optimum profile is actually to enter the atmosphere with downward lift, to get down to the thickest part of the atmosphere as quickly as possible and then roll to a lift-up attitude as close to the surface as you can. That gives you a very long glide out at constant altitude in the densest part of the atmosphere. Even so, a vehicle the size of Red Dragon or larger would never get down below about Mach 3 without propulsion. That’s why parachutes become useless when the vehicle gets too big. Instead, the Red Dragon would have fired its retropropulsion thrusters at Mach 3 and used them all the way to the surface for a soft landing.

A vehicle the size of the Starship, however, would have an entry mass of more than 100 tons. That puts it in a whole new category, especially since it would be carrying humans. When the Space Shuttle returned from orbit it had to limit the deceleration level to no more than 4 g’s to avoid hurting the astronauts. It would be necessary to do the same thing with the Starship, and you can’t stay below that deceleration level and get slowed down enough for landing on a single pass through the atmosphere. Fortunately, it’s entirely possible to make a pass through the atmosphere, skip out, and come back around multiple times. Because the Starship will be made out of Stainless Steel, its surface is reusable probably hundreds of times.

I think the real problem that a vehicle the size of Starship will have is doing a propulsive tail-first landing on an unprepared surface. Rocket motors blasting into loose soil at close range are pretty good at digging a hole right under the landing legs. I don’t know how SpaceX plans to deal with that.

originally posted by: Flyingclaydisk
Mars is notoriously difficult to land on...

NASA came up with some very clever ways to land. My favorite is still the bouncing ball approach. Cushion it enough and maybe a human could do a bounce landing. The other thing that comes to mind is the space elevator that's been proposed on earth. Why not let robots and drones build one on mars.

I'm a big naysayer when it comes to humans on Mars. Of course, the last of the aviator daredevils may eventually make it there in small numbers. Like scientist visitors to the South Pole on Earth. But it's been said that Antarctica is like a stroll in the park compared to Mars, where you have to bring 99.9999 percent of what you need to live with you, including for a long time, air and water.

And with the sizzling radiation blasting everything all the time and just the sheer boredom of having to live with the same group of people for the rest of your life in a shiny tin can buried in the dirt. That sounds ultimately horrible, regardless how much "good science" they might be able to accomplish. Seems to me that setting up a virtual presence there would accomplish just as much or more. Also sample retrieval missions.

But I know I'm in the minority with this opinion, with others holding on to wild romantic notions of daring exploration in their heads, as if somehow it's all going to be like exploring Africa in the 1800s, when it is more like working late in the lab except you never go home forever.

And with the razor dust, that goes double for the Moon. So bon voyage. I'll stay here on Earth where we have stuff like trees and lakes and you can look at them directly with your eyes without a helmet or video camera.

a reply to: 1947boomer

So, pretty much the same thing I said.

LOL!

Landing on Mars is "hard".

LOL!

Cool terminology though.

originally posted by: Bluntone22
a reply to: Flyingclaydisk

Humans going to Mars is a one way trip to an early death.
Months instead of days being hammered by solar radiation.
The low gravity is going to weaken bones and muscles.
No food, no water, lots of dust and sand storms.

Everyone on planet earth will watch these people die a miserable death live on television.


We are not ready for the technical challenges Mars presents..not yet.

Very true. I'll go one further and say it wont happen in our lifetimes, even those in their 20s. Debby downer realist alert: We may not ever have the technology to do it, it might not exist.

Everyone views technology as this limitless, exponential thing that keeps climbing forever. It's just not true. We had a technology boom with nuclear, computers and everything that came with it, but what if that was reaching close to the peak of what we can get, only being able to tweak and enhance those things, maybe develop some new novel ones to accentuate them? No one wants to consider that because it isn't fun on the imagination.

We love imagining all sorts of things that we can do in the future, the possibility being endless.. except they arent endless, we just like to think they are because it's fun and feels good.