50
votes
BBC: "A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and explode." Will it really explode?
It depends on how you define "explosion". Most generally, it merely describes something that breaks into pieces violently. Astronomical impact events can generate explosions simply from ...
- 4,425
38
votes
In what state are satellites left in when they are left in a graveyard orbit?
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 ...
- 732
32
votes
BBC: "A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and explode." Will it really explode?
I think it's worth looking at how much energy that rocket is going to be carrying. Plugging the 4 tonnes and 5000 mph figures into an Online calculator we find that the impact will carry close to 10 ...
- 421
23
votes
In what state are satellites left in when they are left in a graveyard orbit?
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 ...
- 391
20
votes
Accepted
How can Cassini be a source of potential biological contamination?
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, ...
- 406
14
votes
BBC: "A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and explode." Will it really explode?
Energy-wise, I'd call it an explosion
Kinetic energy (KE) = 1/2 mv2
The article quotes the mass at 4 tons, and the speed as 5,000 mph. That gives:
KE = 0.5 * 3628 kg * 2235 m/s * 2235 m/s = 9 ...
- 1,743
11
votes
Accepted
Could the Voyager spacecraft be spin-stabilized to keep their high gain antennas pointing towards the Sun (and therefore Earth)?
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 ...
- 130k
10
votes
Accepted
Do owners of reentering spacecraft notify the countries' whose airspace they are likely to violate and seek permission?
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 ...
- 4,504
10
votes
Accepted
How can Northrop Grumman's Mission Extension Vehicle (MEV-1, 2) "dock with 80% of satellites currently in a geostationary orbit"?
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 ...
- 189k
7
votes
Why end-of-life GPS satellites given orbits that seemingly still intersect active satellite orbits but with a different period? Recipe for disaster?
“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.” ...
- 27.9k
7
votes
Where are MEO satellites put at the end of their operational life?
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 ...
- 122k
5
votes
Would spacecraft rot or degrade over time faster on Mars, on The Moon, or in space?
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 ...
- 151
5
votes
Why are deorbited satellites allowed a slow orbit decay instead of burning them up rapidly?
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 ...
- 77.4k
5
votes
Accepted
Is there an end-of-life policy for Martian satellites?
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 ...
- 58.4k
4
votes
Is there an end-of-life policy for Martian satellites?
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 ...
- 584
4
votes
How would wheel attrition of MSL Curiosity play out to end of mobile mission?
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 ...
- 130k
4
votes
Accepted
How would the Voyagers finally die if allowed to transmit to the bitter end?
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 ...
- 130k
3
votes
Accepted
Coupling satellites already in orbit reduce drag and debris?
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 ...
- 689
3
votes
Accepted
What will (or did) end of mission look like for the MarCo cubesats?
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 ...
- 1,019
3
votes
Accepted
How long could a spacecraft be attached to ISS?
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 ...
- 1,981
3
votes
What typically ends a satellite's life?
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 ...
- 31
3
votes
BBC: "A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and explode." Will it really explode?
Somehow my paper napkin math came out slightly different:
Both rockets have velocity of approximately 9,000 kph. 2,300 kg (LCROSS) will deliver an energy of approximately 1.7 tons of TNT. 4,000 kg (...
- 31
3
votes
Would spacecraft rot or degrade over time faster on Mars, on The Moon, or in space?
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 ...
- 6,300
3
votes
In what state are satellites left in when they are left in a graveyard orbit?
When they are replaced with an updated satellite, GPS satellites are sometimes stored in a pseudosynchronous orbit. This allows them to be reactivated and returned into their previous orbital position ...
- 27.9k
3
votes
BBC: "A rocket launched by Elon Musk's space exploration company is on course to crash into the Moon and explode." Will it really explode?
There are astronomical, volcanic, chemical, electrical, high pressure or nuclear explosions.
None of these kind of explosions may happen.
No supernovae, no very large meteoroid or an asteroid ...
- 49.5k
3
votes
Accepted
Why procure a separate de-orbit vehicle for the ISS? Why can't the ISS flip over and de-orbit itself?
From ISS CONTROLLED DEORBIT: CHALLENGES AND SOLUTIONS, Murtazin et al. (2017):
low thrust capability of all available thruster systems is considered to be a main constraint for the ISS deorbit
The ...
- 10.1k
2
votes
Accepted
What is/was Spitzer's schedule for end-of-life and what will be its final status?
Some "clues" from SpaceflightNow.com's article NASA uplinks final command to deactivate Spitzer telescope.
Ground teams at JPL uplinked a command to Spitzer through NASA’s Deep Space ...
- 1,233
2
votes
How big of a problem is the Lunar eclipse in April 2014 for LADEE?
How big of a problem is the Lunar eclipse in April 2014 for LADEE?
8.5 years later, we know the answer. From Wikipedia's LADEE; End of mission:
The probe then dealt with the April 2014 lunar eclipse ...
- 151k
2
votes
What is the life expectancy of a geosynchronous satellite dependent on?
To calculate life expectancy, there are a few things to consider. The first is to determine how long we want it to last, as this is going to drive other considerations. As the launch cost is a ...
- 84
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