Objects designed to explore the universe are now challenges for spaceflight | Hacker News Reader

Objects designed to explore the universe are now challenges for spaceflight

washingtonpost.com

48 pointsmolecule24 comments

IMO the article overstates the danger of cubesats. If deployed to a low orbit (~ISS height) they deorbit in months due to atmospheric drag. You don't really run into the problems described in the WaPo article until you start putting them into higher orbits where they will last longer.

Here is a more detailed article describing the cubesat problem and potential mitigations.

https://spaceflightnow.com/2015/07/30/nasa-tracking-cubesats...

This is an extremely disingenuous article. Not even the worst case models of the Kessler syndrome predict any real impact on beyond-Earth space flight- rather, they are concerned with higher probabilities of impact over months to years for satellites in specific overused low earth orbits. Nothing for comms satellites in geostationary to worry about, let alone a rocket just going past orbit to the moon or Mars. It's definitely something for scientists to think about and track so specific useful orbits stay useful, but has nothing to do with space flight. It's wild how much this idea has been misrepresented in the media!

[0] https://en.m.wikipedia.org/wiki/Kessler_syndrome

I know this is a long shot but is it possible to detect life on other planets by the metal and trash sphere all modern societies must eventually accumulate around their planet? We have just begun, I can only imagine how crazy it is going to get around our own planet.

Perhaps, but we are still dealing with the challenge that the light of a star completely dominates the light from planets nearby. Telescopes like the James Webb Space Telescope schedule for launch in 2018 should be able to filter out the starlight and theoretically perform spectroscopy on the planetary light, which could reveal biomarkers like oxygen in the atmosphere.

No. The total mass of metal up there is nothing in comparison to natural stuff like dust and atmosphere. And the metal is in very low orbits. Someone far away would see our cities, our atmospheric pollution, long before detecting a hint of orbital debris.

The satellite launch the article references was mostly nano stats from Planet Labs. These satellites are designed to deorbit and burn up on rented with a lifespan of about 2 years. Space debris is a problem, but they could have done a much better job motivating that problem with something more accurate.

I thought satellites in orbit suffered decay and needed Station Keeping, or small periodic thrust to keep their orbits. Does anyone know how long it takes orbital decay to bring a satellite back into the atmosphere?

The lame answer is "it depends", but you might find this chart enlightening: http://www.heavens-above.com/IssHeight.aspx

Cool data. What happened in January 2017?

Measurement error

One Solar Powered Laser in High Orbit pressuring trash into lower orbits would be enough to clean stripes up. Activation of course only over naval territories and clouded waters. In Addition warn every vessel in the path about whats going down.

Solveable problem

I was wondering about the same thing. Would the forcing pressure of such a laser be great enough to deorbit heavy things? I know that a laser + sail has been suggested as one way of accelerating objects in space, so presumably so?

Maybe the US military would want to bankroll something like this. "Mostly used for peaceful space junk clean up... mostly"

Sounds like we need to bring back Star Wars and laser them out of the air! Kidding/Not Kidding.

Actually an interesting idea. If the Starshot project [1] (which uses ground-based laser propulsion) gets off the ground, perhaps the system could be equally useful for de-orbiting space junk.

Firing at orbital objects as they approach from low on the horizon could produce an ablative thrust that could accelerate the natural de-orbiting process.

[1] https://en.wikipedia.org/wiki/Breakthrough_Initiatives#Break...

Wouldn't one-sided heating, from earth, quite frequently lead to them being moved into a higher orbit (one side gasses off, conservation of momentum leads to movement)? That sounds quite hard to predict exactly and thus might end up being pretty dangerous for objects on other orbits.

Thrust in the radial direction (straight out) unintuitively does not raise an orbit; it increases eccentricity, so the highest point is higher and the lowest point is lower, but since the impulse is orthogonal to the direction of motion it does not add any energy to the object.

In any case, heating from the Sun vastly outweighs anything coming from the Earth, and so would tend to push the object inwards on average.

You can get orbit raising/lowering from outgassing and radiation pressure with a rotating object [https://en.wikipedia.org/wiki/Yarkovsky_effect], but that depends entirely on rate and direction of rotation.

> Thrust in the radial direction (straight out) unintuitively does not raise an orbit; it increases eccentricity, so the highest point is higher and the lowest point is lower, but since the impulse is orthogonal to the direction of motion it does not add any energy to the object.

That doesn't really address the point that that'd make it dangerous due to hard to predict flight paths - and the outgassing wouldn't just happen directly outwards for all broken up parts.

> In any case, heating from the Sun vastly outweighs anything coming from the Earth, and so would tend to push the object inwards on average.

In the case of trying to destroy orbiting garbage via laser from earth (the OPs proposal, not my idea!)? You'd pretty fundamentally need higher energy than the sun delivers, albeit for obviously a very limited amount of time.

Low-tech solution: cowcatchers.

If the cow is traveling 10 miles per second relative to the catcher, both simply explode and create more cows.

On a positive side, space polluted with micro-sateliets will deter an alien invasion. No generation ships parked in a near orbit.

I assure you, space debris of that nature would likely be a very solvable problem for a civilization capable of building and operating an interstellar generational starship.

hmm...I wonder if all these new satellites could possibly be part of some new cheap, high-speed internet system? That would be great for consumers, I guess, but bad for the profits of comcast, et al. I would also be against this pollution of our pristine natural wonderland of outer space, especially if it cut into corporate profits.

High speed and really bad latency, maybe.

Current satellite internet has high latency, because it's going thorough geosynchronous satellites about 25,000 miles up.

The SpaceX (https://arstechnica.com/information-technology/2016/11/space...) and other similar proposed satellite internet constellations would be made of lots of low-orbit satellites a couple hundred miles up. Latency wouldn't be much of a concern there.

Reply on news.ycombinator.com