Big, dead satellite's crash was a space-junk wakeup call, experts say

[Admin]

The uncontrolled reentry of the European Space Agency's defunct ERS-2 satellite was a reminder that operators should plan out the safe demise of their spacecraft.

Big, dead satellite's crash was a space-junk wakeup call, experts say : Read more

 

[Pogo]

I’ve often thought “What about all the material that vaporizes in the atmosphere, now we have many elements and compounds as vapors in what we’re breathing that was not intended to be there.
Early in the Shuttle program, it was noted that they have found micro spheres of aluminum oxide in the atmosphere from the solid rocket boosters.

 

[Nammy]

They didn't even take into consideration animals, particularly mammals, living in the oceans who could get hit and injured or die by said debris, nor they mention how much that junk is contaminating the waters. This pollution will only get worse.
They need to design a robot ship or drone that they can launch like a satellite into orbit, and as each piece of junk gets decommissioned, that drone will go to the junk, tow it away from Earth, and push it towards the moon, where it can crash without harm. Then the drone can return to orbit and wait till next month before it needs to repeat that mission.
If someday, any metal or chemical was in the junk that can be salvaged, they can do so.

 

[billslugg]

Space travel is extremely costly, sending trash to the Moon would damage it for any future scientific studies. The cost of moving things around is proportional to the changes in velocity needed to get it there. Dumping things into the atmosphere is the cheapest way to get rid of satellites. Here are the delta V numbers:
- Launch into orbit at 250 km takes 9256 meters per second

- Slowing it down enough to re-enter takes 20 meters per second off of that.
- Sending an object to the Moon and landing it takes adding 5661 m/s.

The cost of sending to the Moon is 283 times more than de-orbiting into the ocean.

 

[Unclear Engineer]

Some comments on the economics:

1. Bill is basically correct that the choice is mostly based on the delta-V requirements. And, delta-V requires propellants, so Nammy's thinking about having a drone make repeated moves to send dead LEO satellites to the Moon simply neglects that the drone would need a huge number of refueling flights from Earth to support those repetitive delta-V moves. There are cheaper solutions.

2. It is feasible to require new satellites to have precision de-orbiting capabilities, similar to what we have for human space-fight vehicles. That requires more delta-V to get the craft into a steeper decent path so that there is less uncertainty where the craft will land. That means more propellant and maybe bigger thrusters, so more weight to launch per kg of scientific/commercial payload. But, it seems very feasible.

3. Making satellites last longer in orbit would save money, so long as those satellites remain useful. But , part of the problem with commercial satellites, especially communication "constellations", is that they are quickly superseded by advancements in technology, so are quickly "throwaways" after a short time in LEO. So, refueling in orbit for commercial LEOs is not likely to solve the problem for the majority of near-future reentries.

4. If it becomes a scientific or political necessity that we substantially reduce the amount of vaporized satellite materials we allow to be created in our upper atmosphere, then it would probably be feasible, but somewhat costly, to make heat shields that survive reentry for all satellites, so that they do hit the Earth's surface intact. With the precision reentry requirement, such returned materials might even be recyclable to a substantial degree. Landing areas could be on land, in government owned areas with exclusion of humans and perhaps even large animals where/when impacts are scheduled.

5. The choice of ablative materials on the reentry heat shields might be based on what materials we least worry about (or even most want) getting deposited in our upper atmosphere.

All of these ideas cost money and are not likely to ever be commercially profit-making, even with recycling of materials or even components from intact landings. So they would have to be adopted as government policies and enforced with government regulations.

That might be difficult to enforce at the international level, even now with only the U.S. Russia and China having the means to put much into orbit. As other countries such as India, Iran, North Korea, and later some African and South American countries gain orbital capabilities, it will probably be a real challenge to keep the human safety and especially the environmental protection priorities high on all of their agendas.