Pit stop in L2?

RobertDyck · 2014-03-16 09:03:01

From a Robert Zubrin presentation: Mars Direct: Humans to the Red Planet within a Decade - Nasa

Note: Total delta-V (km/s) to go from Earth to surface of Mars is lower than to surface of the Moon. The reason is you have to use propulsive landing on the Moon, while Mars has an atmosphere.

Last edited by RobertDyck (2014-03-16 09:24:39)

RobS · 2014-03-16 12:18:23

This appears to be low lunar orbit, not L1. Stopping at L1, refueling, and heading back to Earth for trans-Mars injection seems to add about 0.6 to 1.0 km/sec to the total trip, and you'd do it only if lunar fuel were cheap enough at L1. I doubt that is possible, since you could aerobrake it to low Earth orbit and avoid the extra stop.

Quaoar · 2014-03-18 02:05:52

RobS wrote:

This appears to be low lunar orbit, not L1. Stopping at L1, refueling, and heading back to Earth for trans-Mars injection seems to add about 0.6 to 1.0 km/sec to the total trip, and you'd do it only if lunar fuel were cheap enough at L1. I doubt that is possible, since you could aerobrake it to low Earth orbit and avoid the extra stop.

Or reaching L1 slow spiraling with a cheap solar electric propulsion, and then the crew reach the spaceship and leave for Mars.

Quaoar · 2014-03-18 13:59:29

RobS wrote:

Hard to tell what the electrical propulsion is achieving when they have a chemical stage along as well.

I found the solution in this article ( http://www.kiss.caltech.edu/workshops/s … Propulsion )

The Tug reachs an high orbit spiraling out with electric propulsion, then performes a close lunar approach using Moon's gravity to low the perigee to LEO

RobS · 2014-03-18 14:06:26

Ah, they are using xenon. Right now, no one can produce 40 tonnes of xenon; the world production is too low. Furthermore, the cost of xenon is astronomical; $10 per liter is what I just found. A liter has 5.9 grams of xenon, so that equals about $1.8 per gram and $1.8 million per tonne. The Falcon Heavy should be launching chemical propellant to orbit for $1 million per tonne, less if the outer cores prove reusable. So this system won't be economic, especially after the development cost of a 300 kilowatt power system and ion engines are considered.

Quaoar · 2014-03-18 15:57:44

RobS wrote:

Ah, they are using xenon. Right now, no one can produce 40 tonnes of xenon; the world production is too low. Furthermore, the cost of xenon is astronomical; $10 per liter is what I just found. A liter has 5.9 grams of xenon, so that equals about $1.8 per gram and $1.8 million per tonne. The Falcon Heavy should be launching chemical propellant to orbit for $1 million per tonne, less if the outer cores prove reusable. So this system won't be economic, especially after the development cost of a 300 kilowatt power system and ion engines are considered.

I couldn't realize why they pretend to use xenon, when argon is more and more abundant and cheaper. An electric propulsion using xenon is doomed to reamain forever on the paper.

RobS · 2014-03-18 17:18:58

You need to use a lot more electricity to ionize argon, so you need more power to get the same thrust.

Quaoar · 2014-03-19 02:40:21

A cheeper propellant with a lower ionization energy dosn't exist?

RobertDyck · 2014-03-19 04:56:44

Lithium metal? There is work on that. It means a solid propellant, so completely different feed system. And Russians did some work with Krypton and Bismuth. Krypton has ionization energy of 1350.8 kJ/mol for the first ion, while Xenon has 1170.4; so Krypton requires slightly more electricity than Xenon. But Krypton is lighter: 83.798 g/mol while Xenon masses 131.293 g/mol. Krypton costs $33 per 100g, while Xenon costs $120 per 100g. And this chart claims about 10 times as many litres of Krypton as Xenon are produced per year.

Just ensure you don't have radioactive isotope krypton-85 dissolved in solid quartz. Especially with Be++ and Fe++ dissolved, creating green quartz. Kryptonite. Ok, way to much work for a lame joke.

Quaoar · 2014-04-08 09:48:57

I found this work ( http://pdf.aiaa.org/preview/CDReadyMJPC … 8_4520.pdf ) about a direct evaporation bismuth Hall thruster.

Bismuth is cheep and has a lower ionization energy than xenon.

Mars_B4_Moon · 2022-07-05 08:16:17

L points could become a valuable place to set an array of observation satellites but also communication networks, lack of radio communications can also be caused by ionospheric anomalies, solar activity or during re-entry of a spacecraft, we also see with the War in Ukraine civilian communication networks may be subject to radio jamming from an aggressive imperialist state, even if its slower by snail mail each planet or Asteroid of the Solar system could have a satellite that replays information meaning there would be almost no blackouts.

James Webb Space Telescope, designed to operate near the Earth–Sun L2. Due to the natural stability of L4 and L5, it is common for natural objects to be found orbiting in those Lagrange points of planetary systems. Objects that inhabit those points are generically referred to as 'trojans' there are also the ' Jupiter trojan asteroids'. The Sun–Earth L4 and L5 points contain interplanetary dust and at least two asteroids, Earth–Moon L4 and L5 points contain concentrations of interplanetary dust, known as Kordylewski clouds. The Sun–Neptune L4 and L5 points contain several dozen known objects, the Neptune trojans, there is speculation that China may send a Nuclear Orbiter to Neptune, the planet Mars has four trojans. Chang'e 2 was placed onto a heliocentric orbit that took the Chinese spacecraft past the near-Earth asteroid 4179 Toutatis. There are quasi-stable periodic orbits called halo orbits around these points in a three-body system. The L3 point lies on the line defined by the two large masses, beyond the larger of the two. Within the Sun–Earth system, the L3 point exists on the opposite side of the Sun, a little outside Earth's orbit and slightly closer to the center of the Sun than Earth is. Soho is at L1 since the 90s and WIND at L1 since 2004.

Optimal Location of Relay Satellites for Continuous Communication with Mars
https://www.researchgate.net/publicatio … _with_Mars
A two-satellite Gangale orbit relay system provides optimum performance. We then investigate the propellant requirements for a Gangale orbit insertion and station-keeping in light of non-gravitational forces. We conclude that the Gangale orbit configuration is practical from these points of view.

NASA’s CAPSTONE Probe Is Officially en Route to the Moon
https://gizmodo.com/nasas-capstone-head … 1849140591

Chang'e 5 orbiter enters 1st Lagrange Point of Sun-Earth system
www.china.org.cn/china/2021-03/20/content_77330591.htm

Japanese venture Company in Tsukuba First to Commercialize Lasers Connecting Space and Earth: The laser communication network could revolutionize disaster response, along with private telecommunications, space exploration.
https://japan-forward.com/venture-compa … and-earth/

Last edited by Mars_B4_Moon (2022-07-06 05:47:40)

Mars_B4_Moon · 2023-06-28 11:35:34

Maybe a communication network, traditionally L4 and L5 Sun–Mars Lagrangian points have been sometimes called Mars trojans maybe they will be pit stops for building communication stations?

New laser communications system arrives at NASA for Artemis 2 moon mission

https://news.yahoo.com/laser-communicat … 44473.html

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#26 2014-03-16 09:03:01

Re: Pit stop in L2?

#27 2014-03-16 12:18:23

Re: Pit stop in L2?

#28 2014-03-18 02:05:52

Re: Pit stop in L2?

#29 2014-03-18 13:59:29

Re: Pit stop in L2?

#30 2014-03-18 14:06:26

Re: Pit stop in L2?

#31 2014-03-18 15:57:44

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#32 2014-03-18 17:18:58

Re: Pit stop in L2?

#33 2014-03-19 02:40:21

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#34 2014-03-19 04:56:44

Re: Pit stop in L2?

#35 2014-04-08 09:48:57

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#36 2022-07-05 08:16:17

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#37 2023-06-28 11:35:34

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