Author Topic: NEP AG transit to Mars  (Read 56699 times)

Offline JohnFornaro

  • Not an expert
  • Senior Member
  • *****
  • Posts: 10974
  • Delta-t is an important metric.
  • Planet Eaarth
    • Design / Program Associates
  • Liked: 1257
  • Likes Given: 724
Re: RE: NEP AG transit to Mars
« Reply #80 on: 03/26/2009 11:51 pm »
Here's the link to the download area.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=1219&start=1 - which is for presentations and video in L2.

Is there a different level of membership?  when I hit this link, I am told it is not for me to view.  Thanks
Sometimes I just flat out don't get it.

Offline Kaputnik

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 3079
  • Liked: 722
  • Likes Given: 821
Re: NEP AG transit to Mars
« Reply #81 on: 03/29/2009 06:15 pm »
Yes, there's the Level 2 area which is subscription only.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

Offline mlorrey

  • Member
  • Senior Member
  • *****
  • Posts: 2173
  • International Spaceflight Museum
  • Grantham, NH
  • Liked: 23
  • Likes Given: 5
Re: RE: NEP AG transit to Mars
« Reply #82 on: 04/01/2009 09:48 pm »
For manned missions the ~12 month NEP transit to Mars (versus the commonly quoted 3 months for NTR) is a big disadvantage. I know which one I'd prefer to be on.  NEP certainly has uses in unmanned deep space, like in the original JIMO concept.

Shouldn't the transit be faster than 12 months? I thought it was 6 months each way. A Hohmann transfer should leave Earth when it is opposite (aphelion) from the point in Mars orbit where Mars WILL BE when the craft reaches it, which should occur at conjunction.
VP of International Spaceflight Museum - http://ismuseum.org
Founder, Lorrey Aerospace, B&T Holdings, ACE Exchange, and Hypersonic Systems. Currently I am a venture recruiter for Family Office Venture Capital.

Offline JohnFornaro

  • Not an expert
  • Senior Member
  • *****
  • Posts: 10974
  • Delta-t is an important metric.
  • Planet Eaarth
    • Design / Program Associates
  • Liked: 1257
  • Likes Given: 724
Re: NEP AG transit to Mars
« Reply #83 on: 04/01/2009 10:13 pm »
Figgered out the subscription thing, and am now subscribed...  Thanks, Chris.
Sometimes I just flat out don't get it.

Offline kfsorensen

  • aerospace and nuclear engineer
  • Full Member
  • ****
  • Posts: 1568
  • Huntsville, AL
    • Flibe Energy
  • Liked: 150
  • Likes Given: 0
Re: RE: NEP AG transit to Mars
« Reply #84 on: 04/01/2009 11:40 pm »
Shouldn't the transit be faster than 12 months? I thought it was 6 months each way. A Hohmann transfer should leave Earth when it is opposite (aphelion) from the point in Mars orbit where Mars WILL BE when the craft reaches it, which should occur at conjunction.

NEP/SEP transfers to Mars have different orbital dynamics than ballistic (high-thrust) trajectories.  Ballistic trajectories leave the departure planet and arrive at the destination planet with significant relative velocities, whereas the EP trajectories leave with little excess velocity and arrive at nearly a matching velocity.  They take longer to fly, but I wouldn't look at this as much of a disadvantage.

Offline mlorrey

  • Member
  • Senior Member
  • *****
  • Posts: 2173
  • International Spaceflight Museum
  • Grantham, NH
  • Liked: 23
  • Likes Given: 5
Re: RE: NEP AG transit to Mars
« Reply #85 on: 04/04/2009 06:10 am »
Shouldn't the transit be faster than 12 months? I thought it was 6 months each way. A Hohmann transfer should leave Earth when it is opposite (aphelion) from the point in Mars orbit where Mars WILL BE when the craft reaches it, which should occur at conjunction.

NEP/SEP transfers to Mars have different orbital dynamics than ballistic (high-thrust) trajectories.  Ballistic trajectories leave the departure planet and arrive at the destination planet with significant relative velocities, whereas the EP trajectories leave with little excess velocity and arrive at nearly a matching velocity.  They take longer to fly, but I wouldn't look at this as much of a disadvantage.

Hmm I'm not sure this is entirely accurate. The studies I saw for VASIMR propelled missions to Mars show it actually takes less time than a Hohmann transfer, with the big time waster being crawling out of Earth's gravity well. After that happens it is more or less heading directly for Mars.
http://www.space.com/businesstechnology/technology/vasimr_rocket_020807-1.html
http://nextbigfuture.com/2007/11/vasimr-engines-plus-200-mw-of-nuclear.html
http://dma.ing.uniroma1.it/users/bruno/Petro.prn.pdf

Constant thrust electric propulsion with their high Isp actually attains much higher average velocities than the chemical or other high thrust/short burn, although the real time savings of such methods is more readily seen in missions to the asteroids and beyond.

Getting nuclear reactors into space is the big stumbling block. I am hoping that Lonnie Johnson's JTEC system could provide a zero moving parts solar thermal power plant thats 60% efficient, which would be a much higher power density than PV or nukes.
VP of International Spaceflight Museum - http://ismuseum.org
Founder, Lorrey Aerospace, B&T Holdings, ACE Exchange, and Hypersonic Systems. Currently I am a venture recruiter for Family Office Venture Capital.

Offline Chris Bergin

Re: NEP AG transit to Mars
« Reply #86 on: 04/05/2009 04:09 am »
This thread was taken off course, split it. Keep it on NEP AG transit to Mars from now on, or we'll just delete the posts.
« Last Edit: 04/05/2009 04:10 am by Chris Bergin »
Support NSF via L2 -- Help improve NSF -- Site Rules/Feedback/Updates
**Not a L2 member? Whitelist this forum in your adblocker to support the site and ensure full functionality.**

Offline Kaputnik

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 3079
  • Liked: 722
  • Likes Given: 821
Re: NEP AG transit to Mars
« Reply #87 on: 04/05/2009 02:49 pm »
Does anybody have a good source of information on these EP Mars transfer trajectories? I'm thinking some sort of table of examples showing the transfer times attainable with a certain thrust and isp. I'd imagine it's a much harder thing to calculate than a simple one-impluse Hohmann transfer.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

Offline kfsorensen

  • aerospace and nuclear engineer
  • Full Member
  • ****
  • Posts: 1568
  • Huntsville, AL
    • Flibe Energy
  • Liked: 150
  • Likes Given: 0
Re: NEP AG transit to Mars
« Reply #88 on: 04/05/2009 04:10 pm »
Does anybody have a good source of information on these EP Mars transfer trajectories? I'm thinking some sort of table of examples showing the transfer times attainable with a certain thrust and isp. I'd imagine it's a much harder thing to calculate than a simple one-impluse Hohmann transfer.
I've done a large number of them.

Offline Lampyridae

  • Veteran
  • Senior Member
  • *****
  • Posts: 2641
  • South Africa
  • Liked: 949
  • Likes Given: 2056
Re: NEP AG transit to Mars
« Reply #89 on: 04/06/2009 03:27 am »
Does anybody have a good source of information on these EP Mars transfer trajectories? I'm thinking some sort of table of examples showing the transfer times attainable with a certain thrust and isp. I'd imagine it's a much harder thing to calculate than a simple one-impluse Hohmann transfer.
I've done a large number of them.

I guess they'd be a lot tougher than patched conics. Do you use CATS? How detailed are the models?
« Last Edit: 04/06/2009 03:28 am by Lampyridae »

Offline GI-Thruster

  • Full Member
  • ****
  • Posts: 732
  • Liked: 4
  • Likes Given: 0
Re: NEP AG transit to Mars
« Reply #90 on: 04/06/2009 04:53 am »
Not sure if this is helpful but it's interesting:

http://koti.mbnet.fi/jarmonik/Orbiter.html

Offline kfsorensen

  • aerospace and nuclear engineer
  • Full Member
  • ****
  • Posts: 1568
  • Huntsville, AL
    • Flibe Energy
  • Liked: 150
  • Likes Given: 0
Re: NEP AG transit to Mars
« Reply #91 on: 11/15/2014 03:32 pm »
A spacecraft like this might be even more suitable for an attempt to visit Ceres. The low gravity of Ceres would play to the strengths of the propulsion technology. I look forward to the information from the Dawn probe on the suitability of Ceres as a future target of exploration.

Offline Proponent

  • Senior Member
  • *****
  • Posts: 7277
  • Liked: 2782
  • Likes Given: 1462
Re: NEP AG transit to Mars
« Reply #92 on: 11/16/2014 11:20 am »
Does anybody know what the numerical forward-trajectory model (RKF56) is?

Offline kfsorensen

  • aerospace and nuclear engineer
  • Full Member
  • ****
  • Posts: 1568
  • Huntsville, AL
    • Flibe Energy
  • Liked: 150
  • Likes Given: 0
Re: NEP AG transit to Mars
« Reply #93 on: 11/16/2014 01:28 pm »
RKF56? Runge-Kutta-Fehlberg 5th/6th order method with error estimation.
« Last Edit: 11/16/2014 04:19 pm by kfsorensen »

Offline kfsorensen

  • aerospace and nuclear engineer
  • Full Member
  • ****
  • Posts: 1568
  • Huntsville, AL
    • Flibe Energy
  • Liked: 150
  • Likes Given: 0
Re: NEP AG transit to Mars
« Reply #94 on: 07/10/2022 03:36 pm »
Here's a first blush at an animation of the concept.  Fuel tanks and engines aren't shown yet, but I hope you like it anyway:


Offline kfsorensen

  • aerospace and nuclear engineer
  • Full Member
  • ****
  • Posts: 1568
  • Huntsville, AL
    • Flibe Energy
  • Liked: 150
  • Likes Given: 0
Re: NEP AG transit to Mars
« Reply #95 on: 07/10/2022 03:42 pm »
I did a little digging last week and came to realize that this concept goes back much, much further than I thought.  Ernst Stuhlinger was apparently thinking along the same lines with his work in 1957 and also in 1962:





Here's some great work by Nick Stevens on modern renders of these concepts:




Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: NEP AG transit to Mars
« Reply #96 on: 07/11/2022 09:36 pm »
Almost 8 years later! Heck of a necro-bump (70 years if you count the original idea you dug up!). I like it it, Sorensen!

Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0