Flight Question Mars Transfer Vehicle.

[orbitingpluto]

So far a concept like thishttp://www.orbithangar.com/searchid.php?ID=5208 is what I have used for Mars landings. But these landers are big so maybe just follow the concept.

You might be interested post #7 of this thread, where I pointed out a few other Mars addons in addition to that one.

Could 'Helium' refer to Helium-3, which would implicate a fusion engine?

I don't know what Astro has in mind, but a Helium-3 fusion-powered nuclear engine kinda seems too far-future for what he is up to.

Regarding the perils of getting down to Mars surface and, even worse, getting back up to orbit: Mars is a planet, big enough to make these operations a nightmare. To get back up would rather require landing a fully fueld Falcon 9 rocket safely on its surface, ready for launch back into orbit. This is closer to reality than an Apollo LM with a heatshield.

I agree with all of this, except the sizing of Mars Ascent vehicle. I think something in the neighborhood of a Falcon 9 would be overkill, though I'm not about to calculate a better analogy rocket. I would make a wild-ass guess at something similar to a first generation Atlas, though.

The idea of splitting the mission into a separate lander and a Mars ascent vehicle may look tempting, but has a danger of its own: If the landing approach fails, the crew of the lander would be doomed, as they cannot abort the landing.

Did I really did say to split the ascent vehicle off into it's own vehicle?

To answer my own question: yes, yes I did.:facepalm:

 

[Delta glider]

You might be interested post #7 of this thread, where I pointed out a few other Mars addons in addition to that one.

:facepalm:

 

[orbitingpluto]

francisdrake's comment of "Apollo LM with a heatshield" plus a few pictures got me thinking a bit; hopefully the pictures make up for the fact I'm not going to type that much out.

Mars DRM lander, safely tucked into a big aeroshell:

Two DRM landers on the surface:

Astro's design, no shell, only a heatshield on the bottom:

The DRM landers all get encapsulated in aeroshells to survive the entry into Mars's atmosphere, and looking at Astro's lander, there doesn't seem to be any physical reason it wouldn't fit into a similar aeroshell. That way, it should be better protected than with the current idea of just protection from below.

 

[Delta glider]

The DRM landers all get encapsulated in aeroshells to survive the entry into Mars's atmosphere, and looking at Astro's lander, there doesn't seem to be any physical reason it wouldn't fit into a similar aeroshell. That way, it should be better protected than with the current idea of just protection from below.

I do not even think that Astro's design would work, as the ionizing plazma will vaporize the entire vehicle, but that is just a speculation.

---------- Post added at 08:00 PM ---------- Previous post was at 07:57 PM ----------

In fact, you could look into the Uranus/Neptune mission concepts and the aeroshells in their look good as they are smaller. The DRM1 ones are 10 metres in diameter! And 90 metric tonnes.

 

[orbitingpluto]

In fact, you could look into the Uranus/Neptune mission concepts and the aeroshells in their look good as they are smaller. The DRM1 ones are 10 metres in diameter! And 90 metric tonnes.

Similar, but not the same. I can't speak for any specs on Astro's design, but since it looks smaller both in diameter, height and capability(seriously, one of the landers brings a pressurized rover down with it), a lander of his encapsulated should not be expected to mass the same as a DRM1 one.

The main driver behind volume and mass of any aeroshell is the stuff inside it. Robotic probes like the ones in the outer planets thread don't have to contain payloads like Mars ascent vehicles, nuclear reactors, habitats, or rovers, and thus don't have the big aeroshells the DRM1 study proposed.

 

[Astro SG Wise]

So, am I hearing conflicting opinions? I have thought about that, I have never been able to get the MTV with a heatshield to actually survive in orbiter, no matter how realistic it is or not.

You see, the heat shield does not allow for enough "shadow room" in which the lander can sit, let alone adding fuel tanks to the sides in my drawn out design. I was using the heat shield for the [ame="http://orbithangar.com/searchid.php?ID=6429"]BM lander[/ame], and it is most likely possible that the BM is unrealistic, so the cargo wouldn't truly survive. Now, I have never thought of using an aeroshell, but that proves a good point Pluto. If the heat shield was shortened in diameter (to match the diameter of the SLS core stage), and an aeroshell added, then it would be much easier on the vehicle. The only problem is, with the BM's large heat shield, I have never been able to slow down enough, it just busted through the Martian atmosphere and hit the ground still burning. I would recommend the addition of a parachute system and supersonic decelerators.

I have done some considering of the Constellation program, and I realize that the DRM landers seem equally reasonable, if not better, because it is harder to rendezvous the landing cargo vessels together on the ground when the are smaller, than when they are few in number. It seems that landing DRMs is a better choice, but what will NASA actually do? The Constellation program is "canceled", and so will NASA still use the old designs for the Orion/SLS Mars mission?

 

[orbitingpluto]

So, am I hearing conflicting opinions

I didn't state this before, but I do think that having just a heatshield on the bottom won't work. I didn't want to be too negative, which ended up creating it's own problem- sorry about that.

So yeah, no conflict of opinion.

You see, the heat shield does not allow for enough "shadow room" in which the lander can sit, let alone adding fuel tanks to the sides in my drawn out design. I was using the heat shield for the BM lander, and it is most likely possible that the BM is unrealistic, so the cargo wouldn't truly survive. Now, I have never thought of using an aeroshell, but that proves a good point Pluto. If the heat shield was shortened in diameter (to match the diameter of the SLS core stage), and an aeroshell added, then it would be much easier on the vehicle. The only problem is, with the BM's large heat shield, I have never been able to slow down enough, it just busted through the Martian atmosphere and hit the ground still burning. I would recommend the addition of a parachute system and supersonic decelerators.

Keep in mind those aeroshells enter the atmosphere on their 'side' with the black tiles facing down. Instead of just having the X square meters of the circular heatshield, the areoshell has the area of one entire side of the aeroshell to work with. Parachute are definitely a must, though I'm not so certain about something like the supersonic decelerator. Where would it attach, and how?

I have done some considering of the Constellation program, and I realize that the DRM landers seem equally reasonable, if not better, because it is harder to rendezvous the landing cargo vessels together on the ground when the are smaller, than when they are few in number. It seems that landing DRMs is a better choice, but what will NASA actually do? The Constellation program is "canceled", and so will NASA still use the old designs for the Orion/SLS Mars mission?

Nobody knows. The closest thing to a Constellation era Mars plan was(I think) DRM 5, but figuring out what might be approved and actually carried out, as opposed to being cancelled at some point seems like too tall a task. There's predicting the future over the short term(2-5 years), then there's predicting the future over the decade or two a Mars mission would be in development and then be carried out.

However, the DRMs happen to the design reference for Mars missions, hence the the name Design Reference Mission. Should NASA get the budget and instruction to carry out a mission to Mars, the first step would be taking the latest DRM and not only freshening it up a bit and fleshing it out, but also making a few adjustments based on budget or current capabilities.

You could make the assumption that NASA will carry out a Mars Mission, and just work on figuring out a technically realistic mission, while ignoring making it politically and budgetary realistic. Compared to accurately predicting the whims and reasons of Government and the American public, rocket science is easy.

 

[Delta glider]

Drouge chutes slow you down from supersonic speeds.

 

[Astro SG Wise]

I didn't state this before, but I do think that having just a heatshield on the bottom won't work. I didn't want to be too negative, which ended up creating it's own problem- sorry about that.

So yeah, no conflict of opinion.

Gotcha, thanks, I understand, but don't worry about hurting my feelings. :thumbup:


The Aeroshell on the DRMs had one side black, and one side white, but couldn't we extend the black a little on both sides and have the central heat shield take the heat? Based on size, this heat shield would be bigger than Orion's, and Orion can take way more than the Martian atmosphere.

Secondly, I agree, prediction :crystalball: would be a little too hard, because different presidents would be cycling through the executive branch, and you never know about congress! I think that NASA would try a smaller lander, and send cargo via smaller rockets, i.e. Atlas V, Delta IV, or da big SLS (but extremely expensive). I think this because they say they can only launch a few SLS rockets a year, and they better start working soon if they want to get all that cargo to Mars on a schedule like that!

If so, that they focus on a smaller lander like mine, I think they should implement an Exploration Mission Three to test the capabilities of this lander, the Orion MPCV, and SLS together, kinda like an Apollo 9 on steroids.

Thanks for the comments everyone!

(Oh, and P.S.: The Heat shield would bring the vehicle to a safe atmospheric level, the supersonic decelerators would be under the aeroshell (which would jettison after re-entry burn), they would open, and a parachute would slow it down even more. At a certain speed, the heat shield (with supersonic decelerator bags) would jettison, the parachute would be cut, and the lander would fire it's engines, open it's great, and in the end, save fuel.

 

[orbitingpluto]

The Aeroshell on the DRMs had one side black, and one side white, but couldn't we extend the black a little on both sides and have the central heat shield take the heat? Based on size, this heat shield would be bigger than Orion's, and Orion can take way more than the Martian atmosphere.

The problem isn't thermal protection, but surface area to work with; you need to interact with quite a bit of atmosphere to slow down, and with Mars's thin atmosphere, you need as much surface area as you can get.

Hopefully you see what I mean? Also, the back plate is looks more like a back shell than a actual heatshield, but I can't look though the DRM 1.5 document I have right now to confirm that suspicion.


I'll reply more later.

 

[Astro SG Wise]

Yes. I agree. If the problem isn't thermal protection, once the vehicle slows down just enough so plasma isn't surrounding itself, it could jettison the aeroshell cover, deploy supersonic decelerators, and then the parachute. Once, those slow down to a certain point, the vehicle would jettison the heat shield, cut the parachute, and land on it's engines.

 

[Delta glider]

Yes. I agree. If the problem isn't thermal protection, once the vehicle slows down just enough so plasma isn't surrounding itself, it could jettison the aeroshell cover, deploy supersonic decelerators, and then the parachute. Once, those slow down to a certain point, the vehicle would jettison the heat shield, cut the parachute, and land on it's engines.

:yes:

 

[orbitingpluto]

Yes. I agree. If the problem isn't thermal protection, once the vehicle slows down just enough so plasma isn't surrounding itself, it could jettison the aeroshell cover, deploy supersonic decelerators, and then the parachute. Once, those slow down to a certain point, the vehicle would jettison the heat shield, cut the parachute, and land on it's engines.

I'm not sure if you got my actual point. You don't have to move around the thermal protection stuff- the aeroshell has those tiles on that one side, because from the side it presents the greatest amount of area to the atmosphere. Take a second look at the picture I posted and estimate the area of the bottom verses the side, and it should be easy to tell which is bigger.


Also keep in mind that adding a whole bunch of stages(exit aeroshell, deploy supersonic decelerator, exit supersonic decelerator, deploy parachutes, exit chutes, deploy gear and landing engines, engine burn..) is the opposite of keeping it simple. Read this line from the DRM 1 document:

Mars orbit capture and the majority of
the Mars descent maneuver is performed
using a single biconic aeroshell. The decision
to perform the Mars orbit capture maneuver
was based on the facts that (1) an aeroshell
will be required to perform the Mars descent
maneuver no matter what method is used to
capture into Mars orbit, (2) the additional
demands on a descent aeroshell to meet the
Mars capture requirements were determined
to be modest, and (3) a single aeroshell
eliminated one staging event, and thus one
more potential failure mode, prior to landing
on the surface.

The less the there is to go wrong, the greater the chance it will all work right; so goes the argument, at least.

 

[Astro SG Wise]

I'm not sure if you got my actual point. You don't have to move around the thermal protection stuff- the aeroshell has those tiles on that one side, because from the side it presents the greatest amount of area to the atmosphere. Take a second look at the picture I posted and estimate the area of the bottom verses the side, and it should be easy to tell which is bigger.


Also keep in mind that adding a whole bunch of stages(exit aeroshell, deploy supersonic decelerator, exit supersonic decelerator, deploy parachutes, exit chutes, deploy gear and landing engines, engine burn..) is the opposite of keeping it simple.

So, for your point, your saying that you don't even need to add tiles to the aeroshell?

Yeah, also the addition of the other functions is more complicated, but is it harder to land the DRM? (P.S., the supersonic decelerators are attached to the heat shield, and so there is no decelerator exit, just to be technical :facts:.)

---------- Post added at 01:17 AM ---------- Previous post was at 12:57 AM ----------

Also, when I inspect the Mars Direct Mission concepts, the cylindrical landers seem quite similar to the MTV, at least in function. They have an fold-out deploying heat shield, and no aeroshell.

https://www.youtube.com/watch?v=mU7KBhUGrfE

---------- Post added at 01:24 AM ---------- Previous post was at 01:17 AM ----------

Also, on the topic of stack designs, what about three RNSs!

https://www.youtube.com/watch?v=xOgFIq03Nm4

 

[orbitingpluto]

So, for your point, your saying that you don't even need to add tiles to the aeroshell?

Exactly. It already has all the tiles it needs. I wish I hit upon this comparison earlier, but the aeroshell is more akin to a lifting body than a traditional capsule. In other words, what we both have been calling the bottom of the aeroshell is actually it's aft end, and the actual bottom is the side covered in black tiles. For what it's worth, I figured a graphic might be in order. Sorry about the using paint, it what I have handy:

Hopefully this gets my point across, though I must admit I probably held up your understanding by not being clear enough.

Also, when I inspect the Mars Direct Mission concepts, the cylindrical landers seem quite similar to the MTV, at least in function. They have an fold-out deploying heat shield, and no aeroshell.

https://www.youtube.com/watch?v=mU7KBhUGrfE

That lander narrows inward like a cone though, unlike the mostly cylindrical DRM landers or your modified LTV. Most of it sits in the shadow-zone(not sure if the term) of the heatshield, so there's that difference.

Your modified LTV is more similar to a DRM lander than a Mars Direct lander, which is why I'm arguing that a aeroshell might work out best. Depending what you came up with, I might have thought Von Braun's old 1952 glider-thingy might have been appropriate to bring up, but....

You know what, I can't quite imagine what sort of modern mission plan that glider could be a be reasonable part of.

Also, on the topic of stack designs, what about three RNSs!

https://www.youtube.com/watch?v=xOgFIq03Nm4

NASA Marshall's art department did more than a few illustrations of the RNS, this one being the most relevant:

Three RNS strapped together was not only an anticipated mode of operation, but it was expected. It boggles my mind, what these planners were thinking of.

 

[Astro SG Wise]

So, on the point of the DRM, I have seen the Constellation videos, and I do understand the DRM lander's attitude at re-entry. But, my lander design comes down on a bottom heat shield, not a side aeroshell (or bottom in the case of the DRM). So, wouldn't the LTV design be a combination of the cylindrical Mars Direct Mission landers with an aeroshell covering it, like the DRM? Take a look at that video again. The Mars Direct Mission lander isn't just the conical shuttle-looking lander, but there are completely cylindrical landers as well.

---------- Post added at 12:15 PM ---------- Previous post was at 12:14 PM ----------

Oh, and on RNS, thanks for the info. I still need to figure out how to launch RNS from SLS, but all my SLS scenarios freeze on me. I have a terrible installation.

---------- Post added at 03:00 PM ---------- Previous post was at 12:15 PM ----------

Sorry about the using paint, it what I have handy

If you think that's bad, I should be the one being sorry! :lol:

 

[Astro SG Wise]

So, this is my most recent schematic of the Lynx MTV lander. This picture does not include RCS, Parachutes, Heatsheild module, or batteries/solar panels. I am going to post it fast now, but I will speak more on it later. Cheers!

---------- Post added at 12:51 AM ---------- Previous post was at 12:50 AM ----------

(This design maximizes fuel, and minimizes living space.)

 

[Astro SG Wise]

Part 1: Stack Transfer

So, I have have studied multiple different concepts recently, and I have an arsenal of information on the subject of Mars transfers at this point, but I would like to address a few concerns separately.

For the first time, I recently have transferred to Mars, using IMFD. Problem? I had to refill some things with scenario editor to get into Martian orbit. This is what my MOHV stack looked like once it was on the way to Mars.

It uses the [ame="http://orbithangar.com/searchid.php?ID=5339"]Reusable Nuclear Shuttle[/ame], [ame="http://orbithangar.com/searchid.php?ID=3055"]Solar Service Module[/ame], and the Orion MPCV addons. I also, in a later trial, used the [ame="http://orbithangar.com/searchid.php?ID=3819"]vessel stack[/ame] addon to control three RNS boosters at once (more on that later :facepalm. Anyway, what I used to do, to get to Mars in this stack configuration, was to use the single RNS to boost a target intercept program on IMFD, but I kept refilling it, to simulate having two other RNS boosters along side it. A few big errors I found:

1) SLS can't even lift a fully loaded RNS in the first place! I have been coming up with a concept to use only 8 SLS launches for a Mars mission, but that number even seems unrealistic, and I would never be able to do an orbit insertion.

2) Can the two, side RNS boosters really boost the entire configuration on the way to Mars, not even using the main booster's fuel?

3) How much fuel would the third booster really have in the end? When I view the Von Braun KSP Mars Mission, they use the last booster to get back all the way to earth! Using IMFD, even when I refill the booster when I get done with the preliminary transfer burn, I still don't have enough fuel (sometimes) to even get into orbit insertion.

4) The SSM module is not a realistic size. A better module to use would be Skylab II, but the problem is, if I can barely get to Mars as it is, what would a heavy barrel like Skylab II do?

IN SUMMARY: The concepts look all nice and pretty, but after experimenting for the past few months, the RNS boosters seem to weak, the payloads are still undersized, and the crew is NEVER getting back at this rate :rant:.

A few interesting things noted along side this project: the NERVA2 addon is much more efficient than RNS. Why? Is it the size of the engine? I used that, and I got the best results, but still run into the problem of fuel consumption.

In the end, when I watch the Constellation Mars Stack, the Direct to Mars missions, and others, they always seem to have an amazing amount of fuel in the end. Any explanations? Am I doing the burns wrong?

Thanks. Also, some more pictures...

 

[orbitingpluto]

Hopefully I can shed some light on your questions, but before that, a question of my own: what does your TMI burn look like? Part of of the problem could be an inefficient transfer eating up more dv than it should, leaving less for MOI and latter TEI, and leading to stranded astronauts. A screencap of your plan in IMFD should be enough for someone to figure out if something is wrong, though I'm not going to be that someone- I'm rather out of practice.

On with your questions.

1) SLS can't even lift a fully loaded RNS in the first place! I have been coming up with a concept to use only 8 SLS launches for a Mars mission, but that number even seems unrealistic, and I would never be able to do an orbit insertion.

I have a bit of deja-vu typing this but whatever: The RNS was designed to be launched on either a Saturn V with only part of it's full propellent load at launch, or fully tanked on a uprated Saturn V derivative. The SLS can't quite match the Saturn V, so you'll have to offload quite a bit of prop at launch.

This does have the effect of requiring tanking flights to fill up the RNS(s), ether requiring a few SLSs or having a bunch of smaller rockets launching tankers. Or you have an even bigger rocket than the SLS, and launch the RNS full.

Also, this is more me getting up on semantics than an actual problem, but for a nuclear rocket, the fuel is the nuclear material in the reactor, and the stuff you run through the reactor and out the engine bell to produce thrust is the propellent. Calling propellents fuel makes sense from an Earthy perspective with cars and whatnot, and works well enough with chemically propelled rockets(both propellents combust) but nuclear rockets are different. I'm not sure if I explained this before, but whatever.

2) Can the two, side RNS boosters really boost the entire configuration on the way to Mars, not even using the main booster's fuel?

That was the plan. It would take a really long burn, but the there's enough prop for it. This mission plan is pretty similar, though it's PPM is quite a bit different than the RNS. You might get more confidence when you run the numbers through the rocket equation and figure out the delta-v of your stack. This online calculator is helpful if you don't know how to run a spreadsheet.

3) How much fuel would the third booster really have in the end? When I view the Von Braun KSP Mars Mission, they use the last booster to get back all the way to earth! Using IMFD, even when I refill the booster when I get done with the preliminary transfer burn, I still don't have enough fuel (sometimes) to even get into orbit insertion.

That video doesn't quite matter as much as the fact that you are having problems getting to where you want to go with enough propellent to do MOI and latter TEI. It sounds like your trajectory planning is off, so you ought to focus getting help with that. Like I said above, you can post about the plan you use for TMI and hopefully you can get help in making a more efficient one.

Part of your problem might be choosing poor dates for departure, this trajectory browser should help with that.

4) The SSM module is not a realistic size. A better module to use would be Skylab II, but the problem is, if I can barely get to Mars as it is, what would a heavy barrel like Skylab II do?

Better than either would be [ame="http://orbithangar.com/searchid.php?ID=5247"]Transhab[/ame], and you have the option of switching from the RNS to something with an intergrated hab like the [ame="http://orbithangar.com/searchid.php?ID=2713"]Crew Transfer Vehicles[/ame]([ame="http://orbithangar.com/searchid.php?ID=2789"]plus update[/ame] and [ame="http://orbithangar.com/searchid.php?ID=2794"]cargo version[/ame]) by andymc. But that a bit different than what your currently using, and it's up to you if making a switch is really worth it.

IN SUMMARY: The concepts look all nice and pretty, but after experimenting for the past few months, the RNS boosters seem to weak, the payloads are still undersized, and the crew is NEVER getting back at this rate :rant:.

Part of it is your navigation skills don't seem up to the task, but that's something that will get better with practice and learning. Humans to Mars is just plain difficult to improbable even with the best equipment we have and the most skill musterable, so go easy on yourself when you can't quite get things working. It's not easy, nor is there a definitive guide to getting things right.

A few interesting things noted along side this project: the NERVA2 addon is much more efficient than RNS. Why? Is it the size of the engine? I used that, and I got the best results, but still run into the problem of fuel consumption.

The NERVA2 uses a closed-cycle gas core reactor, which allows the propellent to be heated beyond the temperature the solid core NERVA that the RNS uses allows, meaning a hotter and thus higher exhaust velocity. Higher exhaust velocity means more omph per kilogram.

I would wish that you would spend more time reading Atomic Rockets than watching Youtube, since Atomic Rockets is chockfull of stuff to stretch your mind and teach you all sorts of stuff, like the difference betwixt solid core and closed-cycle gas core, but making demands on anyone's free time is something I should stay away from.

Sorry for being a bit grouchy, here's to the hope this helps you out.

 

[Astro SG Wise]

Thanks a lot. I definitely should look at numbers and actual systems information, rather than watch animations for solid stone truths anyway. So, yes, I did think about the date-of-fire. I used the scenario "before orbit raise" for the Design Reference Mission One addon. I supposed that would be the best day to do it on, seeing that those NTR boosters, with seemingly less fuel, could get heavier payloads to Mars there.

I will have to do more research, but I have found that NASA and Boeing are obsessed with Solar Electric Propulsion as the main propellant source. Then again, we could do it Zubrin's way, but I thought that nuclear made the most sense as a happy medium.

Thanks again. I will continue experimenting. :tiphat: