131

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 ...


61

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 ...


37

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 ...


23

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 ...


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 ...


11

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 ...


10

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 ...


9

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 ...


9

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, ...


7

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)


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

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

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 ...


5

“As of Feb 2019, there are 31 satellites in the GPS constellation, 27 of which are in use with the rest allocated as stand-bys… More decommissioned satellites are in orbit and available as spares.” Wikipedia When the GPS system decommissions a satellite, and the system wants to use that orbit location for a replacement, they can either dispose of the ...


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

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

I am not aware of any such policy; the primary reason for having one on earth satellites is to avoid accumulation of 'orbital space junk' that can endanger astronaut/cosmonaut safety and pose an unnecessary hazard to operation and other experiments or investments that are in orbit or will go into orbit in the future. Satellites sent to other solar bodies ...


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 ...


3

In this scenario, the last straw would be the hydrazine freezing which leads to loss of the thrusters. After a while, the loss of attitude control means Earth drifts out of view of the HGA. The impression I get from reading a lot about Voyager's systems in the last few days is that quite a large part of Voyager's power budget seems to be going towards ...


3

Possible but unlikely. If you want to join satellites securely than you need to add some kind of docking mechanism to the satellites and that adds a lot of complexity at which point you can just have thrusters to dodge debris or counteract the drag. Additionally I think having more satellites bunched up in one area means that if a collision happens there ...


3

The limiting factors for docked vessels is typically fuel decomposition time and losses due to outgassing or leaks while for non-docked vehicles it's consumables1 being, well, consumed. In the case of the former, take Soyuz-MS. As mentioned in a previous answer, in normal use it is limited to 210 days docked due to the decomposition of its Hydrogen ...


3

The mission for MarCO A and B was to perform a relay of communications for the Insight lander, which lowered the latency of data during landing, and that mission was a success. The mission ended on November 26, 2018 and JPL lost contact with them on January 4, 2019. Source MarCO A and B successfully completed their missions on Nov. 26, 2018. WALL-E was ...


3

Your question is What typically ends a satellite's life? and the answer is, as often, "it depends". In the nominal case, lifetime is limited by fuel. All satellites need to perform orbit and attitude maneuvres using small rocket engines and are required to keep an end-of-life fuel reserve for de-orbiting, GEO stationary satellites are required to be moved ...


3

One question I really wanna ask; do spaceship's rot? Sort of, yes. In terms of "rotting", in the sense that a spacecraft will lose material or undergo degradation of its material components, then spacecraft do encounter this problem in the space environment for a variety of reasons. One big reason is atomic oxygen (that is, O, not O2), which is present in ...


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