https://www.vox.com/recode/22839485/space-station-iss-orbit-satellites

Noel

All good things eventually come to an end.  If we, as humans, wish to expand our knowledge of space we will have to venture from orbit and back to the moon, then on to Mars.  Beyond that, we really need faster means of travel, but in venturing back to the moon and Mars, we may develop such means.  Paging Doctor Zefram Cochrane.  Doctor Cochrane, please answer the red phone.

Will all future space stations in low Earth orbit,  regardless of their size, be designed to have a 20-30 year life like the ISS and then be dumped into the Pacific Ocean? Is this because it's too expensive to build and launch more robust stations? Some of the ISS modules are less than 10 years old. I assume the replacement station will be modular also and some of these existing modules could be incorporated, even just as storage areas.

I don't know that a space can be or should be designed to last longer.  Technology changes and it may not be feasible to incorporate new technology into a 20 or 30 year old space station.  Also, I would think the massive temperature swings and radiation bombardment would degrade the exterior surfaces and maybe even the insulation and barriers beneath a space stations exterior material.

3 hours ago, stans said:

I don't know that a space can be or should be designed to last longer.  Technology changes and it may not be feasible to incorporate new technology into a 20 or 30 year old space station.  Also, I would think the massive temperature swings and radiation bombardment would degrade the exterior surfaces and maybe even the insulation and barriers beneath a space stations exterior material.

What would that mean for larger space stations or the proposed orbiting space hotel? By the time construction is completed, the earlier modules would already have to be replaced. The large space station in 2001 - A Space Odyssey would be completely impossible.

The Hubble Space Telescope, for example, was launched in 1990 and is expected to last until 2040. Five Space Shuttle missions have repaired, upgraded, and replaced systems on the telescope, including all five of the main instruments.

If we are serious about colonising our solar system, we have to find practical solutions to the problem of degradation. I don't think built-in obsolescence is an option.

With all of the space stations they plan on sending up there and all of the satellites going up to give a few Inuits in northern Greenland internet access plus all the space junk that's orbiting around how do you prevent collisions?  It's going to happen just as sure as there will be an automobile collision in Los Angeles today.  It'e inevitable.

Noel 

23 minutes ago, birdguy said:

It'e inevitable

Any day now.

47 minutes ago, dmwalker said:

What would that mean for larger space stations or the proposed orbiting space hotel? By the time construction is completed, the earlier modules would already have to be replaced. The large space station in 2001 - A Space Odyssey would be completely impossible.

The Hubble Space Telescope, for example, was launched in 1990 and is expected to last until 2040. Five Space Shuttle missions have repaired, upgraded, and replaced systems on the telescope, including all five of the main instruments.

If we are serious about colonising our solar system, we have to find practical solutions to the problem of degradation. I don't think built-in obsolescence is an option.

The space environment is incredibly harsh--between high ambient levels of high-energy ionizing radiation and even higher bursts from solar flares, micrometeorite strikes, and large thermal gradients between illuminated and dark surfaces, I'd guess modular replacement to keep any long-term project on-orbit would eventually result in something that resembles the old farmer's favorite axe--"it's had three handles and four heads."

Hubble has the advantage of not needing fail-safe life support systems like those required in a manned station.  If something critical fails, we lose our big eye in the sky, but not lives.  Man-rated systems drive much more stringent requirements, as even a temporary failure can be a disaster.

We're a long way still from developing/perfecting the necessary technology to field manned space systems with extended longevity...I think planned obsolescence is a practical (yet admittedly expensive) approach that acknowledges the reality of turnover and modernization as we strive for needed major leaps in materials and propulsion technology.

14 minutes ago, w6kd said:

something that resembles the old farmer's favorite axe--"it's had three handles and four heads."

But works just as well as the original!

15 minutes ago, w6kd said:

We're a long way still from developing/perfecting the necessary technology to field manned space systems with extended longevity

I hope someone is working on that now, otherwise we'll always be a long way. I think we have been conditioned to accept planned obsolescence as the norm and good for business - on Earth, at least.

32 minutes ago, birdguy said:

With all of the space stations they plan on sending up there and all of the satellites going up to give a few Inuits in northern Greenland internet access plus all the space junk that's orbiting around how do you prevent collisions?  It's going to happen just as sure as there will be an automobile collision in Los Angeles today.  It'e inevitable.

The ISS orbits at ~248 nm altitude, which is considerably lower than the low-earth satellites that generally orbit between 311-1250nm altitude.  The ISS has to be resupplied with fuel to regularly re-boost the vehicle, as it is low enough to continuously decelerate due to drag from interaction with the very far reaches of the outer atmosphere.  Operators of low-earth birds don't want to be down there in the weeds with big manned platforms because they can't resupply a satellite with fuel to keep it from decaying into a fiery re-entry.  The biggest risk is from debris from unruly boosters passing through its orbital altitude on the way to higher orbits.  A lot more attention is being paid to how/where expendable launch vehicle flotsam is jettisoned during launches.

If the sky is a big place, then the orbital "shells" that satellites and space stations occupy are far bigger.  Imagine the jet routes we fly extending up to 300,000 feet (50nm) instead of 41000 ft and how much more traffic it could support.  Then extend that out to geosynchronous altitudes (18243 nm) and extrasynchronous orbits that range even higher.  The available orbital space is immense.  It has to be carefully managed, but it isn't "inevitable" to have a manned space vehicle collide with debris.  "Could" it happen--sure, never say never, but the risk is well-understood and being managed daily.  NASA and the the USAF have terrific space-object tracking systems that allow manned vehicles (and some unmanned vehicles) to adjust their orbits to avoid objects...since Kepler is in the driver's seat for everything without a motor, computer modelling of orbiting objects is pretty accurate and allows time to adjust the orbit enough to avoid collisions.

The sky, big as it is, is expanding, not falling.  😉

1 hour ago, w6kd said:

NASA and the the USAF have terrific space-object tracking systems that allow manned vehicles (and some unmanned vehicles) to adjust their orbits to avoid objects

I presume the main concern is with orbiting debris so I wonder how small a piece of debris can be tracked and is there a limit to how many pieces the system can track? Could it track millions of objects, if necessary?

Also, what happened with the Chinese space station and the Starlink satellites? That shouldn't have been possible, should it? Are private companies not positioning their satellites accurately enough?

The word 'chaos' comes to mind Dugald.  How many angles can dance on the head of a pin before one falls off.

We have to expect there will be space fatalities.  We and the Russians have already had some.  And the astronauts who volunteer to go up there know the risks and are willing to take them.  But even so, it is going to be a shocking disaster when it happens to an orbiting space station.  And the more stuff we put up there the greater the danger becomes.

Noel

1 hour ago, dmwalker said:

I presume the main concern is with orbiting debris so I wonder how small a piece of debris can be tracked and is there a limit to how many pieces the system can track? Could it track millions of objects, if necessary?

Also, what happened with the Chinese space station and the Starlink satellites? That shouldn't have been possible, should it? Are private companies not positioning their satellites accurately enough?

We can track and establish the orbital parameters of very large numbers of *very* small objects.

I don't think the Chinese complaint about StarLink sats near their space station was ever acknowledged as fact by SpaceX or the US.  Given how the Chinese government complains every time the US conducts an international law-compliant freedom of navigation exercise in the South China Sea, and how they themselves have, on numerous occasions, intentionally endangered US aircraft and ships with aggressive close maneuvering from fighter jets and naval surface vessels in international airspace/waters, I'm pretty reticent about taking any of that rhetoric at face value without confirmation from a trustworthy source.

11 minutes ago, w6kd said:

I don't think the Chinese complaint about StarLink sats near their space station was ever acknowledged as fact by SpaceX or the US.

Although, I suppose, not acknowledging isn't the same as denying. 

47 minutes ago, birdguy said:

The word 'chaos' comes to mind Dugald.  How many angles can dance on the head of a pin before one falls off.

A whole lot of them...ummm..."angles"...at least when they're being choreographed by supercomputers. 

I think there's more risk of a fatal event related to irradiation from a major earthward X-Class solar flare or coronal mass ejection, or a micrometeorite strike as there is from hitting fairly predictable orbiting debris.  Without doubt, space is a dangerous place, and we will lose people as long as we continue to operate manned missions there.  It's all a matter of relative risk and how it can be managed.  Astronauts aren't generally suicidal, and they know what the risks are before they climb into a rocket.  Now a dumb billionaire jumping in for a paid sightseeing trip is different...that's just a roll of the Darwinian dice for thrills, much like bungee jumping or eating a big plate of Fugu.  I won't weep for them when one of those boondoggles goes bad.