Community > Forum > The Spaceflight Cafe > ISS a safe haven?

ISS a safe haven?

Posted by: Andy Hill - Fri Sep 02, 2005 1:33 pm
Post new topic Reply to topic
 [ 20 posts ] 
ISS a safe haven? 
Author Message
Space Station Member
Space Station Member
avatar
Joined: Thu Jan 27, 2005 12:34 am
Posts: 450
Post Instability Examined   Posted on: Tue Sep 06, 2005 5:54 pm
Instability and stability in a spacecraft is a complex problem, and no nonrotating satellite is actually stable. An orbiting satellite which rotates slowly, so as to remain oriented with respect to the Earth, can be stable, but only within a rather limited zone of moment of inertia matrix parameters. But instability may be no big deal. A car is unstable, and will not follow a road without a driver. An airplane is unstable and will not follow an airway without a pilot or an autopilot.

The ISS, and all other space stations are unavoidably UNSTABLE with respect to AIR DRAG. Thus propulsion must be used to avoid the fate of SKYLAB -- reentry. The ISS attitude instabilities, as with other objects in unstable equilibrium, can be overcome by attitude sensing and use of small thrusters to correct deviations from equilibrium while the effects are still small. An unstable equilibrium, unlike a stable one, will respond to a perturbation with increasing and often accelerating deviations. Thus active correction must be used, and preferably done while the errors are still small. However, properly positioned thrusters could be used to correct the attitude errors in a space station at the same time they were compensating for the air drag, so the extra cost in fuel and energy to actively correct for instability could be near zero.


This is not a defense of the ISS as a “safe haven”. NASA has repeatedly elected not to finish the development of practical “lifeboats” and personal reentry equipment (the equivalent of ejection seats and parachutes). Military pilots are not afraid to use parachutes, with Oxygen supplies for high altitude ejection. The U-2 pressure suits and equipment were sufficient for ejection in vacuum. Reentry shields, as ablative plastic dishes, are no big deal, nor are satellite telephones and GPS to direct rescue. The decision to pursue “Rube Goldberg” “safety systems”, with all the problems discussed here - instead of these derivatives of established military practice - testifies to perverse thinking at NASA.

Bigelow’s dreams of space habitat will never come into existence without affordable “lifeboats” or personal reentry systems, nor will any other serious enterprise in space. I don’t know when the few million dollars needed to test these systems (as supplemental orbital payloads) will be committed, but the funding for these kinds of fundamental tools reveals the true enthusiasm for space development – or the lack of it!


Back to top
Profile WWW
Moon Mission Member
Moon Mission Member
avatar
Joined: Tue Feb 10, 2004 2:56 am
Posts: 1104
Location: Georgia Tech, Atlanta, GA
Post    Posted on: Wed Sep 07, 2005 2:03 am
Fortunately, we also have some highly intelligent people working on these problems who also have their acts thoroughly together: I don't doubt that such systems will be up and running within a few years of private orbital stations being built.

_________________
American Institute of Aeronautics and Astronautics
Daniel Guggenheim School of Aerospace Engineering

In Memoriam...
Apollo I - Soyuz I - Soyuz XI - STS-51L - STS-107


Back to top
Profile
Moon Mission Member
Moon Mission Member
User avatar
Joined: Fri Jan 09, 2004 11:52 am
Posts: 1379
Location: Exeter, Devon, England
Post    Posted on: Wed Sep 07, 2005 12:35 pm
just posted at article on the front page regarding bigelow's space stations, worth a gander if ur bored. would i trust them enough to allow my familoy aboard!? ha!

_________________
> http://www.fullmoonclothing.com
> http://www.facebook.com/robsastrophotography
> robgoldsmith@hotmail.co.uk


Back to top
Profile WWW
Space Station Member
Space Station Member
avatar
Joined: Thu Jan 27, 2005 12:34 am
Posts: 450
Post Good Information for Career and Investment Plannning   Posted on: Thu Sep 08, 2005 6:56 pm
spacecowboy wrote:
Fortunately, we also have some highly intelligent people working on these problems who also have their acts thoroughly together: I don't doubt that such systems will be up and running within a few years of private orbital stations being built.


I agree with you. The quality of many historic projects and recent work is impressive. However for career planning, strategic planning for the entrepreneur, investment decisions or general interest, the quality of the information publicly available is abysmal! The private concerns you mention – if well funded – have no interest at all in allowing previews of their ongoing work. NASA, for reasons I can only guess, is committed to a policy of disinformation. Many ideas which NASA has rejected will soon prove to be both viable and desirable.

For example, NASA uses “Radiation Hazards” to support their preference for perfecting nuclear propulsion before attempting a Mars Mission. Yet you must search to find that the Earth’s magnetic field screens only 1/3 of the High Z and High Energy Galactic Cosmic Radiation for ISS astronauts. On the way to Mars, the crew will face a modest increase in this radiation. But its effects have already been documented by man years of experience in orbital space, without radiation induced cancer being a conspicuous result!

Life support is the biggest problem for a manned Mars landing, since propulsion needs barely exceed those for the Moon. Bigelow is apparently quite satisfied with his progress in this area. Certainly, he does not plan to haul bathwater up from Earth at the price of Gold! Even with “The Price of Gold” as the cost of orbital payload, a human can be transported to an orbital vacation for One Million Dollars (Not Tito’s 20 Million cost). This price should begin the orbital tourist industry, considering that $200,000 tickets are being sold for a suborbital hop.

It will soon become obvious that NASA is not a leader in space development and that their disinformation has both caused the waste of tens of billions of dollars, and crippled Americans’ opportunity to participate in future space work. If, as I believe, space enterprise will have a positive impact on Earth’s economy, then it is desirable for those of the world’s citizens who would like to participate in it to have reasonably accurate information.


Back to top
Profile WWW
Space Station Commander
Space Station Commander
avatar
Joined: Wed Mar 09, 2005 1:25 am
Posts: 887
Post    Posted on: Thu Sep 08, 2005 8:00 pm
If only Griffin had been chosen instead of Goldin way back when.
Sigh.


Back to top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 20 posts ] 
 

Who is online 

Users browsing this forum: No registered users and 27 guests


© 2014 The International Space Fellowship, developed by Gabitasoft Interactive. All Rights Reserved.  Privacy Policy | Terms of Use