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#76 2018-07-25 16:12:31

RobertDyck
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From: Winnipeg, Canada
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Re: Getting to Mars with REAL technology, & what's currently missing.

I am disturbed we had such a strenuous debate about advanced boosters for SLS. I still believe liquid boosters are superior. But let's move on.

Certain factions in NASA are adamant about the Moon. Ok. My position is a modification of Mars Direct. Send an MD hab unmanned to the Moon, using tether spin for artificial gravity to demonstrate technology for Mars. But while the 1990 Mars Direct would try to use an MD ERV on the Moon, I recommend an Apollo-like architecture. I already described a reusable LM delivered to Lunar orbit via Falcon Heavy, and Dragon with crew via another Falcon Heavy. The hab would require SLS block 2B.

Last edited by RobertDyck (2018-07-27 15:23:13)

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#77 2018-07-25 16:26:27

Oldfart1939
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Registered: 2016-11-26
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Re: Getting to Mars with REAL technology, & what's currently missing.

When I started this thread, I specifically stated that the technology incorporated should be currently OTS and immediately available. Yes, electric thrusters are intriguing, but currently lack adequate power to move a sizable vehicle to Mars in a normal lifetime. This is going to be the ultimate pragmatist's thread. That doesn't mean that research should end, but just not used until we have our first manned flights.

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#78 2018-07-25 17:04:54

SpaceNut
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Re: Getting to Mars with REAL technology, & what's currently missing.

Current launchers but they can not without sub assebly on orbit get anything reasonable for mars to the surface of mars.
Current capsules for earth reentry for humans are getting closer by the day but none at the moment from Orion, Dragon, Starliner and Dreamchaser.
Current habitats for transit to mars are iss modules, lunar gateway from simular base of build, ISS Beam but little else has been built and
lest we for get no artifical gravity and minimal radiation protection.
Current mars capable landers none for humans but cargo a modified skycrane for 1.5 mT.
Current surface habitats none and even a Beam weighs with in the skycrane landing capability.

https://en.wikipedia.org/wiki/Bigelow_E … ity_Module
https://www.nasa.gov/mission_pages/stat … /1804.html
https://en.wikipedia.org/wiki/SpaceX_CRS-8

The BEAM weighs approximately 3,000 lbs (1,360 kg) and travels within the unpressurized cargo hold of a Dragon capsule.
BEAM is expanded from its packed dimensions of 5.7 feet long and just under 7.75 feet in diameter to its pressurized dimensions of 13 feet long and 10.5 feet in diameter and has 560 cubic feet of pressurized volume.

https://en.wikipedia.org/wiki/Mars_Science_Laboratory

NASA has looked into a skycrane system to land larger craft, but the numbers are tough. Curiosity had a total mass of two tons, but a manned lander would probably clock in at 10 or 15 tons. It’s unclear if it would be possible to land something like that on Mars with our current technology.

This where we were hoping for a Red Dragon but that seems to have been nixed at this point.

So I am refering discusion back to the Smallest Human Ascent or Descent Lander for Mars Or Earth

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#79 2018-07-26 10:13:43

knightdepaix
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Registered: 2014-07-07
Posts: 190

Re: Getting to Mars with REAL technology, & what's currently missing.

Can gravity assist help send parcels of chemicals or solids on a space shuttle between two planets of Mercury, Venus, Earth and Mars?

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#80 2018-07-26 12:39:09

GW Johnson
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From: McGregor, Texas USA
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Posts: 3,565
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Re: Getting to Mars with REAL technology, & what's currently missing.

I didn't mean to debate about SRB's.  I merely pointed out the truth about such things.  The real reasons to use or not use them are non-abortable,  and rough ride.  The other fears are irrational,  as long as the joints and seals and the combustion stability are designed and tested by competent folks.  NASA is not competent to do those jobs.  They never built any solids,  they have only bought them.

Be careful restricting yourself only to BEAM for an inflatable module;  that is a specialized experiment-only article done exclusively for NASA,  at ISS. The real Bigelow modules are more like what they have on their site for B-330.  While it hasn't flown yet,  my vague understanding was they wanted to fly a B-330 this year,  using Atlas-5 as the launch vehicle. 

I'm far less educated about electric propulsion than chemical or nuclear thermal propulsion.  However,  from what Kbd512 points out,  some sort of scale-up really is underway for whatever a Hall thruster is,  and it sounds like for VASIMR,  too.  Sooner or later,  that scaled-up stuff will get flown,  albeit maybe not at Mars mission size.  The Hall thruster already flies at small satellite size. 

I'm just guessing that to evaluate how feasible the projected electric-powered flight design is,  we need certain characteristics for both the thruster itself,  and for its solar power supply.  Thruster:  thrust/supplied power and weight/max thrust,  plus thrust and Isp vs power curves.  Solar power:  power/weight and power/area at Earth's distance from sun,  and the "parasitic" weight of power conditioning equipment/power delivered,  plus whatever the upper and lower limits are,  on power produced from a given size.  Just guessing.

I'm also just guessing that for fairly practical travel times to Mars,  the overall vehicle will need to accelerate at something in the 0.005 to 0.010 gee range.  That sets thrust,  once the vehicle mass gets summed up.  That sum is some sort of frame to tie everything together,  plus the thruster,  plus the solar power plant,  plus the ion propellant tank,  plus payload.  The ion propellant tank has an inert mass and an actual propellant mass.  The flow control hardware needs to be in that inert mass. 

What am I missing here?

GW

Last edited by GW Johnson (2018-07-26 12:47:51)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#81 2018-07-26 13:21:13

RobertDyck
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From: Winnipeg, Canada
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Re: Getting to Mars with REAL technology, & what's currently missing.

In year 2000 / 2001, NASA ordered electric engine engineers to learn everything Russians had to teach them. These were the guys who invented the NSTAR ion engine used on Deep Space One. They didn't like being schooled by Russians. But they learned what the Russians had done. While NASA was just experimenting, Russia had used electric propulsion on military spy satellites since the 1960s for station keeping. NASA thought the best Isp you could get from Hall thrusters was 1700 seconds, but Russia had developed their Thruster Anode Layer (TAL) Hall thrusters to work as well as Glenn Research Center's ion engines: ~3000 seconds. Furthermore they had a study for a high power Hall thruster with 8400 seconds and a lot more thrust. A large number of these could send a human mission to Mars. Well, the solar array would be huge, and it would have to slowly spiral out of LEO and spiral down to LMO. But the guys at Glenn took it as a challenge. They started with MPD engine that Princeton worked on, enhanced Isp by switching propellant from xenon to LH2, and applied all the engine enhancements they learned from the Russians, and everything they developed for ion engines. The result was 8400 second Isp. They built it and tested in a lab. It required as much electric power as the Russian Hall thruster, but the Russian one was a study while they had lab tested hardware. So there!

Then the guys working on VASIMR claimed they could do 9000 second Isp. Nothing to prove they could do it, just vapourware. And any third party analysis showed VASIMR would require much much more electric power.

Last edited by RobertDyck (2018-07-26 17:47:07)

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#82 2018-07-26 14:43:37

Oldfart1939
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Registered: 2016-11-26
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Re: Getting to Mars with REAL technology, & what's currently missing.

With the electric thrusters, the acronym TANSTAAFL comes to mind: There Ain't No Such Thing As A Free Lunch. There seems to be a Catch 22 embedded in all these arguments, and when accelerated at a decent rate, the structure associated with the massive soar array needs to be pretty robust, and robustness comes with an associated weight (mass) penalty. The power requirement is obviously what limits available thrust, as does the mass of Xenon available. Pick your vehicle size and the thrust output, but that calculates to an enormous power requirement for a realistic mass to Mars.

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#83 2018-07-26 17:44:06

RobertDyck
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From: Winnipeg, Canada
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Re: Getting to Mars with REAL technology, & what's currently missing.

Mars mission plan of the Russian corporation Energia, from 1988, updated in 1999. Even with thin film solar arrays to reduce mass, it's still huge and slow. The module labelled "Interplanetary Orbiter" is based on Zvezda, the Russian Service Module on ISS.
concept-01.gif
concept-05.jpg

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#84 2018-07-29 18:29:12

kbd512
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Re: Getting to Mars with REAL technology, & what's currently missing.

Oldfart1939,

You need a lot less mass for deployment and stability if you use a tensioned circular array that uses centripetal force for both deployment and structural rigidity.  That is a design characteristic of structures that use tensegrity to achieve structural rigidity.  There is quite a bit of math and experimentation that proves that concept.

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#85 2018-07-30 11:36:32

Oldfart1939
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Re: Getting to Mars with REAL technology, & what's currently missing.

kbd512-

Yes, I understand that in principle; but it also adds an another layer of complexity to integrate into the overall system.

Last edited by Oldfart1939 (2018-07-30 11:37:07)

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#86 2018-07-30 15:14:28

kbd512
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Re: Getting to Mars with REAL technology, & what's currently missing.

Oldfart1939,

I don't know what to tell you, except that any interplanetary transport vehicle will be inherently complex.  It can be both complex and prohibitively expensive to use or it can just be somewhat complicated to deploy if it uses the best technology we have available.

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#87 2018-07-30 22:03:04

Oldfart1939
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Registered: 2016-11-26
Posts: 1,646

Re: Getting to Mars with REAL technology, & what's currently missing.

kbd512-

Just pointing out that increased complexity adds to cost and slows development time. Of course any space mission will be complex, but in the interests of success, I've advocated the KISS approach. We need initial success in order to maintain funding and project interest. My case in point is the Webb Space Telescope: years behind schedule and way over budget; is in jeopardy of cancellation after congressional review!

Chemical technology can get us to Mars NOW (as it could have 40 years ago!). Dr. Zubrin describes the added layers of complexity as "Battlestar Galactica" engineering.

Last edited by Oldfart1939 (2018-07-30 22:03:46)

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#88 2018-07-30 23:32:36

kbd512
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Re: Getting to Mars with REAL technology, & what's currently missing.

Oldfart1939,

I'm not in favor of holding up progress just to obtain a "perfected" vehicle design, but nobody is working on a realistic vehicle design at the moment.  We may as well design something that would work well for the intended use case.  A Cygnus-atop-F9H upper stage with tether and spin gravity is a perfectly viable design for a pair of astronauts.  I proposed that awhile back.  F9H took a lot longer to fly than I thought it would, but that complete redesign of the core stage was more than SpaceX bargained for.  Learning by doing, such as it were.

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#89 2018-07-31 00:55:02

RobertDyck
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From: Winnipeg, Canada
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Re: Getting to Mars with REAL technology, & what's currently missing.

I keep arguing for a minor modification of Mars Direct. It is practical. It could be launched to Mars via SLS block 2B. TMI stage would be the EUS that NASA is developing right now. Live support would be based on equipment currently operating on the US side of ISS, with modifications I have already listed in this thread. Heat shield for atmospheric entry would be ADEPT, which is part of the original Mars Direct. Inflatable greenhouse would be the same width as a double-car garage and twice the length, using Clarus film manufactured by Honeywell. You could add a fibreglass ship thermally applied to the film for added strength, and straps at regular intervals to relieve stress, to squish it for low ceiling and wide (not cylinder), and hold-down during strong wind. Yes, Mars wind is low force due to low atmospheric pressure, but still. Lower deck would not be a full usable deck like MDRS, it would be primarily equipment with airlock and storage compartment for rover & surface science equipment. My modification would include a reusable ITV using aerocapture at each planet, heat shield similar to ADEPT but using Nextel 440 instead of graphite fibre. Aerocapture doesn't generate as much heat, but a reusable heat shield must be more durable. MAV would use LCH4/LOX, with a light-weight capsule for ascent only. ITV would include a single Dragon capsule in case aerocapture fails at Earth. Pre-position MAV on Mars, but hab/lander would be attached to ITV during crew transit, so life support of hab would act as backup for ITV, and if free return is necessary they would have all food in the ITV (transit to and from Mars), as well as all food in the hab (intended for surface stay).

Artificial gravity is a minor step from Gemini 11, demonstrated September 12-15, 1966.
260px-Gemini_11_Agena.jpg

ISS life support equipment
urine_machine_nasa.jpg 468753main_0005602_rs_946-710.jpg ooiss022e043880.jpg

Depiction of Mars Direct, from the year 2000 movie "Mission to Mars". Note the greenhouse attached via soft tunnel, and the lower deck is not full width.
2011-review-mars.jpg

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#90 2018-07-31 08:15:41

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,565
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Re: Getting to Mars with REAL technology, & what's currently missing.

Confinement inside small spaces isn't going to work for years in a mission.  NASA seems to have finally owned up to that,  based on recent reports.  While they don't believe the MDRS stuff,  they have been running their own Mars simulation on a Hawaiian mountaintop with crews of 4 to 6.   After 6 months,  every crew turns on each other and fights. 

What that means is a module the size of a Cygnus for 2 people is too small for the transit,  and a surface hab the size of Mars Direct is too small for 4 -6 people for months to a year's stay.  You might get some psychological relief if you could go outside in something other than a bulky,  confining space suit.  So who's working on that better suit?

People need reconfigurable spaces in which to be alone,  and to congregate.  That takes a lot of pressurized volume.  Based on Bigelow's published numbers,  it looks like the inflatables may be the most practical solution for getting lots of volume. 

GW

Last edited by GW Johnson (2018-07-31 08:17:39)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#91 2018-07-31 11:59:13

RobertDyck
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From: Winnipeg, Canada
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Re: Getting to Mars with REAL technology, & what's currently missing.

I recently suspect spacesuit design is slamming into another problem. The old issue is job protection: when Nixon cancelled Apollo, Dr Paul Webb had completed the first two generations of MCP suit, but his project was cancelled with it. Remaining spacesuit designers wanted to protect their jobs, so they defended the design approach they had used all along. Apollo suits were an incremental improvement on Gemini suits, which were incremental improvements on Mercury suits, which were incremental improvements on suits used by air force pilots for high altitude flights. MCP meant a radical different approach.

But the new problem is Plantary Protection people. Gas bag suits mean astronauts are sealed in an air-tight rubber bag. MCP is a fabric, with nothing sealing your skin. In fact, cooling is by sweat. Eliminating the liquid cooling garment, circulation pumps, radiator/sublimator, and water used for sublimation is a massive simplification and mass reduction. Simplicity = improved reliability, because fewer things to go wrong. Cooling in an MCP suit is a bottle of drinking water, the human body regulates it's own temperature. But JPL has reported a problem that Planetary Protection people won't let Mars rovers go to the most likely places to look for extant life. Yes, I just said rover are prohibited from going to most likely places. The reason is fear of contamination from bacteria that rovers may carry from Earth. If Planetary Protection people are that paranoid, now imagine how they react to a human being with nothing but fabric sealing his skin. Dead skin could flake off, or bacteria carried on skin. I don't think that's a serious risk, but Planetary Protection people apparently do.

So one reason MCP suits are not being developed is they don't project Mars from humans. This reminds me of a scene from the 1989 Batman movie:
hqdefault.jpg

Last edited by RobertDyck (2018-07-31 12:20:21)

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#92 2018-07-31 12:36:35

Oldfart1939
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Registered: 2016-11-26
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Re: Getting to Mars with REAL technology, & what's currently missing.

I am in agreement with Rob on the MCP suit issues. The enema begins in Houston?

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#93 2018-07-31 18:05:50

SpaceNut
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From: New Hampshire
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Posts: 15,806

Re: Getting to Mars with REAL technology, & what's currently missing.

The containment is at issue for when we have an unusual environment that we must train for and it comes from unequal duties for the communal style of living that you are forced into in order to survive. The topic post by louis here
http://newmars.com/forums/viewtopic.php … 04#p148804 illustrates the complexity and how unequal the work loads will be...

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#94 2018-08-01 19:07:20

kbd512
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Registered: 2015-01-02
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Re: Getting to Mars with REAL technology, & what's currently missing.

Robert and Oldfart1939,

Houston has enough crap to deal with already.  Let's not go off and create any more of it.

That said, I'm completely onboard with the MCP suit technology Dr. Webb designed.  It worked well enough to get the job done and was far lighter and more affordable than the current generation of gas bag space suits.

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#95 2018-08-01 22:52:03

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,806

Re: Getting to Mars with REAL technology, & what's currently missing.

Have posted to each of the succesful landers and rovers using Skycrane knowledge to which when we look towards the red dragon mission that was cancelled we can look to making use of a larger heat shield, getting rid of parachutes, intergrating the escape engines like dragons and designing a lander stage that could be refueled that can get us back to orbit.

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#96 2018-08-05 05:49:55

Oldfart1939
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Registered: 2016-11-26
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Re: Getting to Mars with REAL technology, & what's currently missing.

Sooner than later, I suspect Elon Musk will realize the folly of his Red Dragon Mission cancellations. I've elsewhere stated why they should take immediate priority as ground-based transponders for subsequent landings. It's still not too late to do a simple redesign for retropropulsive landings with modified external landing legs similarly attached as in the Falcon 9 first stages.

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#97 2018-08-05 08:28:30

SpaceNut
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Re: Getting to Mars with REAL technology, & what's currently missing.

My question of the falcon first stage is mounting of the legs are they protected enough with regards to a mars lander or do they need to have there own protective shield going around them, that is ejected before use of the engines firing before a landing.
The canted engines of the Red Dragon are protected by the rim and distance to them with a heatshield that is part of the capsule but what would we do for a first stage for launching and landing engies for a heatshield design layout.

The question changes when looking at reuse versus use once for those things that we would consider expendable as in cargo landers, a ISPP unit, A kilowatt reactor lander ect....those are to be from a common landing format but with the specialization that each requires or do we make them not so specialized?

See the images at this post
http://newmars.com/forums/viewtopic.php … 94#p148694
Also the above habitat from RobertDyck's post.

The equation for mars EDL no Parachutes is Heatshield (increasing diameter = higher payloads)  + fuel + engines ( combination of these = higher payloads) = Structural mass (inflatables or composites = higher payloads) + Payload
This is a construction problem and not really a new technology....

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#98 2018-08-05 09:38:10

Oldfart1939
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Registered: 2016-11-26
Posts: 1,646

Re: Getting to Mars with REAL technology, & what's currently missing.

SpaceNut-

My solution to the proposed problem is pretty straightforward. We modify the storage trunk of the standard "Cargo Dragon" to become an integral component of the landing system. (1) Lengthen the trunk by simply adjoining 2 of them to make a trunk twice the existing length. Using scaled down Dragon 1st stage landing legs for landing the whole works. (2) Incorporate additional hypergolic fuel tankage and a centrally mounted and suitably gimbaled engine to land the whole works. Have a blow-off heat shield to protect everything. This system could bring a LOT of "stuff," and even a dedicated nuke reactor which would not be used until a manned mission unloaded several thousand kg of supplies. Something of this scale could probably be boosted into a low energy, long flight time Hohman  transfer trajectory with a delta V of 3.4 to 3.5 km/sec using an uprated Falcon Heavy.

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#99 2018-08-05 12:02:39

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,806

Re: Getting to Mars with REAL technology, & what's currently missing.

images.spaceref.com/news/2010/SpaceX_Overview_TEM.pdf SpaceX Overview by Tom Markusic
Director, McGregor Rocket Development Facility 27 July, 2010

https://www.spaceflightnow.com/falcon9/001/f9guide.pdf
Falcon 9 Launch Vehicle Payload User’s Guide

This pegs the upper limit of what we can send with the current first/second stage configuration.

http://www.spaceflightinsider.com/organ … x-capsule/

Each Dragon capsule uses Draco thrusters, 18 of them, to maneuver in space and upon re-entry. These engines can each produce about 90 pounds-force (400 N) of thrust, and are fueled by the commonly-used dinitrogen tetroxide, an oxidizer, and monomethylhydrazine, a fuel, with which the oxidizer is hypergolic – or spontaneously ignites on contact. Each Dragon capsule has a total launch payload mass of 13,228 pounds (6,000 kilograms) with a total launch payload volume of 883 cubic feet (25 cubic meters). On return, its total payload mass is halved at 6,614 pounds (3,000 kilograms) with a volume of 388 cubic feet (11 cubic meters). Dragon v2 will make use of eight SuperDraco thrusters, which are Draco thrusters with dramatic upgrades, that will be mounted in pairs to the walls of the capsule. These engines are designed to propel the spacecraft out of danger in the event of an incident. Each of the SuperDraco engines can produce up to 16,000 pounds-force (71 kN) of thrust, and would also be used to land the craft “propulsively on Earth or another planet with the precision of a helicopter,

The truck does come in 2 sizes but will search out the mass and what they contain.

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#100 2018-08-06 22:14:36

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,565
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Re: Getting to Mars with REAL technology, & what's currently missing.

Spacenut:

Go take a look at exrocketman.blogspot.com.  The latest thing I posted there is a configuration study for Mars landers.  It does have the date and title for an article I posted last year regarding reverse-engineered performance of the various Dragon configurations.  This includes weight statements and delta-vee capabilities.  Scope is Red,  crew,  and cargo Dragon.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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