126

In order to assure that it cannot crash into Europa or other possible ocean moons and potentially contaminate them with Earth organisms. Juno is qualified to survive the radiation environment up to the end of its mission. After that it could succumb to the radiation at any time and become uncontrollable. Planetary protection then requires the disposal of the ...


60

Why is it necessary to destroy the spacecraft? It's because life might well exist on some of Jupiter's moons. Despite the best efforts to assemble the spacecraft in extremely clean conditions, and despite exposing the spacecraft to vacuum and to the Sun's ultraviolet and X-ray radiation, there's a chance that Earth-borne life remains intact on the ...


36

If the satellite is close to the Earth, a last bit of fuel is used to de-orbit it so that it burns up. If it is farther out, it is moved to a retirement orbit out beyond the used orbits. The last thing done after moving it to the retirement orbit is to permanently disable the communication system so that it doesn't randomly transmit stuff and put noise on ...


33

There are some seals, on some of the modules that have a limited lifespan. The lifespans are in the 20 year range, but they are very hard to replace. Some of them are on the Russian end of the station, (Oldest part of course, in terms of launch, but since also was built even earlier than launch for Mir II usage) and these are the ones exposed to the fuel/...


22

A satellite that is retired ordinarily and not expected to reenter will be passivated. The aim here is to minimize the amount of energy stored in the spacecraft, ideally it will be a dead rock floating in space, far from anything it could interfere with. This includes deactivating the comms to stop interference as zeta mentions, but also emptying the tanks ...


20

Currently all spacecraft start out on Earth and while fairly stringent measures are taken during manufacture to keep them clean it is pretty much impossible to guarantee that no bacteria, viruses, spores or other biological material get in somewhere. Certainly anything which is exposed to untreated air at any point is quite likely to be contaminated with ...


19

The orbital decay is not the reason for abandoning ISS at all. The orbit is constantly being corrected by the cargo ships, plus several modules have their own thrusters for orbit correction. ISS is 15 year old. Mir was in orbit for 15 year when it was deorbited. The ageing shows itself in many aspects on all the stations. ISS, Salyut-7, Mir, Skylab. The ...


17

De-orbiting isn't too bad of an option really. While a really large satellite would still have some pieces intact, it by and large will not be completely intact. Furthermore, the most sensitive things on a spacecraft tend to be the computers, antennas, and cameras. Of those, the only remotely likely to survive re-entry is the cameras, most likely only the ...


15

It will be several years before we get to see what actually happens here. However the overall driver for the currently stated NASA plan is money. (In contrast, the currently stated Russian plan seems disconnected from what one might assume about their budget realities.) If the NASA budget remains flat, and there is all expectation that it will, ...


13

You can't re-purpose Juno after its mission as: Its instruments are designed for a specific mission profile, if you sent it elsewhere it wouldn't be able to produce good science. Its solar panels won't produce enough power if you get much further away from the sun Juno is going to be exposed to a huge amount of radiation which will degrade its instruments, ...


12

The difference between the US Operating Segment (USOS) and the Russian segment is one of self sufficiency. The first module launched, Zarya, was enough to base a station on. Sure not a ton of living and working space but it had all the orbital control, solar, thermal radiators needed to be a space station. After that, everything grew off that initial ...


12

I will use an analogy. As your car gets older it wears out. It gets more and more expensive to maintain as parts fail. At some point it is cheaper to get rid of it and buy a new car. This point may depend on how safe you feel in the car. An old ramshackle rustbucket may be drivable slowly, despite having holes in the floor, broken suspension, no windscreen ...


10

Propellant Typically propellant consumables for station keeping were the limiting factor. Once a Geosat reaches near the end of its propellant life, they need to maneuver it out of GEO so as to free up the slot for its replacement. This has been mitigated somewhat by the use of electric propulsion, where Xenon or the like is used as propellant after being ...


10

There is enough hydrazine to last beyond the end of the mission, about 25% of total tank volume is still available. From Descanso volume 4, you can see enough hydrazine for attitude control is available to last until 2040/2048: As in all communications around the end of life for Voyager operations, this lifetime estimate considers the mission to end when ...


9

tl;dr: Do owners of reentering spacecraft notify the countries' whose airspace they are likely to violate and seek permission? No, there is no requirement for notification, and in most instances there is no notification. There are three main guiding principles of international space law that could apply. The Outer Space Treaty has a vague reference ...


8

This is purely a speculation, as I have not found any official sources to confirm it, but I think they want to be able to view Saturn's pole during the fly by. The trigonometry works out at least: If you want to get a close-up of the polar regions with a lower inclination, like 40, 50 or 60 degrees, the altitude required is larger than the gap between ...


8

This document provides a bunch of useful information on the topic. Some applicable quotes: Space missions impose several critical performance requirements on batteries and fuel cells. Batteries required for space applications must be capable of operating in a hard vacuum and withstand severe launch environments (vibration, shock, and acceleration)....


8

There isn't much information publicly available, but the MEV appears to dock to the one component many satellites have in common: the rocket engine nozzle. An extensible probe from the MEV (on the left) enters the rocket nozzle and (presumably) expands its tip. Frame from a video on the Space Logistics website, annotation mine. A line in the fact sheet ...


7

The vast majority of these have been around the moon. Here's a list of what I can find (Using Wikipedia): Luna- 2 (Spacecraft and rocket) Ranger- 4, 6, 7, 8, 9 Apollo LEMs- Apollo 12, 14, 15, 17. Apollo S-IVB- Apollo 13, 14, 15, 16, 17 1990's missions- Hiten, Lunar Prospector 2000's missions- SMART-1, Moon Impacting Probe, Chang'e 1, Chandrayaan-1, SELENE, ...


6

From the Waiver Request linked from the article in the question: The Boeing 702HPspacecraft design features a reaction wheel pointing control system. As all venting must occur within the capabilities of this pointing control system, the firing of thrusters for venting and to address momentum buildup must be of more limited duration and additional time is ...


5

Why are deorbited satellites allowed a slow orbit decay instead of burning them up rapidly? The ultimate reason is simple: There are no international rules or regulations placing limitations on orbital debris. The only thing that comes close is the Space Liability Convention. That convention is akin to having no speed limits on roadways, including school ...


5

Juno starts its tour of Jupiter in a 53.5-day orbit. The spacecraft saves fuel by executing a burn that places it in a capture orbit with a 53.5-day orbit instead of going directly for the 14-day orbit that will occur during the mission's primary science collection period. The 14-day science orbit phase will begin after the final burn of the mission for Juno’...


5

Not for hazard reasons, but possibly for planetary protection reasons. Orbiters cleaned to Class III have an orbital lifetime requirement, which may require an orbit raising near its end-of-life. If Mars orbiters had a requirement to de-orbit for hazard reasons, then they would all also need to be cleaned as if they were landers, to the IVa level. Or maybe ...


5

Okay, so let's get a few numbers here straight, and then I'll explain why it's an issue, and why we can probably recover from it just fine, hopefully. Let's start with figuring out what the nominal eclipse time is for the LADEE satellite. NASA quotes: The nominal science orbit will be a near-circular retrograde (clockwise) equatorial orbit with a period ...


5

According to Wikipedia Some of the options examined include collision with Saturn atmosphere, icy satellite, or rings; another is departure from Saturn orbit to Jupiter, Uranus, Neptune, or a Centaur. Other options include leaving it in certain stable orbits around Saturn, or departure to a heliocentric orbit. Each plan requires certain amounts of time ...


5

Spacecraft don't rot, nor do they rust (since there is not enough free oxygen anywhere but Earth), but they do degrade in various ways: The most obvious is that chemical and electrical equipment like batteries and on-board computers are severely degraded by the extreme cold and variations of temperature that happen. Electrical equipment is also damaged by ...


4

I'm speculating here, but I think that the broad 'reason' is that that's how they've designed the station. Let me expand on that: the first stations (early Salyut, Skylab), were launched all as one piece. All their maneuvering fuel, consumables, any spare parts, were launched in one go, and that was all you had. These were the so-called "first generation" ...


4

Juno will burn up in the atmosphere, and very violently so (over 40km/s of reentry speed vs Earth's 8; effects scale quadratically), so it will dissipate as trace contamination of the atmosphere, spread to four winds through Jupiter's violent weather. If (dubiously so) any solid pieces survive, they'd sink to the surface of solid hydrogen layer and rest on ...


4

From this Planetary Blog post: Driving on worst-case terrain with no consideration can destroy the wheels quickly: The really bad stuff, it only takes 8 kilometers or so and you can destroy the wheel. This is a wheel that was tested to destruction: As you can see, it's still round, it's coming apart lengthwise and at some point the wheel splits in two....


4

This is an active area of research. As you noted, the main satellites that are in MEO are navigation satellites. The short is they have their own disposal orbits, a bit further beyond the current constellations. It seems that GPS satellites are disposed by raising their apogee by about 1800 km (The perigee seems to remain the same)


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