Hot answers tagged

88

No, because it is not in Earth orbit First the payload does have a purpose: it is a boilerplate, and those have a purpose, namely to "test various configurations and basic size, load, and handling characteristics of rocket launch vehicles". Second, you are asking... is the car equipped with a propulsion system to change its trajectory in case of ...


74

Nibiru is fiction. Nibiru, a purported large object headed toward Earth, simply put - does not exist. There is no credible evidence - telescopic or otherwise - for this object's existence. There is also no evidence of any kind for its gravitational effects upon bodies in our solar system. The nice thing about astronomy is that everyone can do it. You ...


68

Well, gee, this question may as well have my name printed directly on it! Spacecraft protection from the orbital debris threat comes in two flavors: Shield and withstand Detect and avoid To start, page 5 of this NASA paper presents a good first-order approximation of the general LEO orbital debris threat. You'll see some variation with altitude and ...


64

Yes, it's space junk: after about 6 hours, the second stage will stop working and there will be no way to change the trajectory of stage and payload. So it's a non-functional satellite, i.e. junk. An object whose course cannot be controlled, and a potential future navigation hazard. It's not in Earth orbit, so it's unlikely to cause a problem here. There is ...


56

They are hit all the time. It just hasn't been critical. So far. Looking at the outside portion of the Hubble WFPC2 camera after it was returned, I saw a huge number of large and small pits in the paint and underlying aluminum from debris hits. Below is an image of that surface after all of those sites were cored out for analysis. Note that the cores are ...


45

Footnotes: ${}^1$ That the term "Space Junk" (as used in this answer and which is probably the right answer) has a different generally agreed meaning in spacecraft lingo than just plain "Junk" has been pointed out in this answer as well as in in this comment. No. 1. It is Space Art. It started as visual art (we watched it on YouTube, it was beautiful! (...


41

The name Nibiru does appear in science fiction. However, the stuff to which you refer is not science fiction. It's just baloney, malarkey, or "fake news." According to Wikipedia's article Nibiru cataclysm about the phony story, science ficition has made some oblique references to it: A viral marketing campaign for Sony Pictures' 2009 film 2012, ...


41

Yes, I've done it myself in my backyard in suburban Houston. During a spacewalk in ISS increment 50, an MMOD shield intended for the axial port of Node 3 was lost. It's visible in this video floating below station. It ended up reentering about six months later. A few weeks after it had been lost, I noticed that it would be visible from my house, with a ...


38

Spooky This one is subjective. To some, just finding an abandoned spaceship would be spooky. I'll say there's probably not a lot that has to happen to evoke this feeling. Rusted Actually, unless your spaceship never had a breathable atmosphere or the atmosphere was vented before the spaceship was abandoned, rust is totally possible on the inside and ...


36

First off, lunar orbits tend to be unstable due to mascons (mass concentrations, which are places of higher density produced by impacts with the moon that cause it to have a non-uniform gravity field). That means that anything not placed in very specific orbits which weren't discovered until 2001 (frozen orbits as referenced by the first link above) will ...


36

Great question. The exhaust velocity from typical landing engines is about 3 km/s. You can imagine good-sized particles being accelerated to a significant fraction of that, say 1 km/s, which is the muzzle velocity of a rifle. There is nothing in the vacuum to slow them down, other than eventually hitting something, or the ground. 1 km/s is already a good ...


35

The apogee/ perigee of 2019-006A, the object likely shot down, was 260- 282 km, pretty low. Some of that debris could be quite a bit higher, but most of it will be lower, and all of it will have a new perigee/ apogee in that range, which will likely be shrinking quickly. It is expected that it will be similar to the debris cloud from USA-193 (Operation Burnt ...


34

What would you notice first? Satellite navigation: immediately (depending on how often you use satnav) TV: immediately (depending on how often you use TV). Even if you don't use satellite TV yourself, your TV provider may receive some of its channels via satellite within a day or so: weather forecasts no longer include satellite imagery, and accuracy goes ...


34

...adjust the angle of the cow catcher to deflect earthward The catcher could be coupled in a way that would allow it to absorb impact gradually by continuous springs. The problem with this is that it's not possible to deflect debris. Things in orbit are moving around at 10 km/s (20,000 mph!) and when they collide, the impact is so energetic they ...


31

There's a few pieces of information that are needed to explain why one might be wary of 1 cm objects: Objects as small as 4 inches (about 10 cm) can be seen by radars or optical telescopes on Earth Oops, can't see 'em. There are also millions of pieces of debris smaller than a third of an inch (1 cm). In Low Earth-orbit, objects travel at 4 miles (7 ...


30

There are two kinds of depressurization alarm: ΔP/ΔT (rapid depressurization) ATM PRESS (slow leak, or pressure hitting the thresholds) Main steps that are taken: Record incident and contact mission control Take pressure gauge Evacuate into the Soyuz Check if Soyuz descent module is leaking If time remaining (T.res) is less than X minutes, say "Bye-bye" ...


27

The apparent source of the data (as it is linked in the source linked in the description of the author of this map) is http://apps.agi.com/SatelliteViewer/ In this animated view you can see that these are the real orbits: Satellites that currently are in the northern hemisphere show up in the southern hemisphere half a day later. As active station keeping ...


26

The UCS has a list of satellites which can be sorted by launch mass. The top 10 is mostly spy satellites for which it's difficult to determine if they're active or defunct. The heaviest satellite of which I'm sure it's not functional, is Envisat at 8 tons. (1:1 model of Envisat at Space Expo in Noordwijk, the Netherlands) This list doesn't account ...


26

Initial and Bonus Answer: With a volume of 609.31 M^3 and an empty mass of 15,500kg (13,500 kg empty weight plus 2,000kg for the attached Instrument Unit), J002E3 is Apollo 12's S-IVB stage (designated S-IVB-507). It was intended to be placed in a heliocentric orbit following Apollo 12's TLI Burn. Due to insufficient propellant, however, it ended up ...


23

Spacecraft rely on information from earth to avoid space debris, they don't have instruments for scanning and detecting debris. There's a few reasons for this: Power: most spacecraft don't have enough electrical power to run a radar powerful enough to detect small debris far enough away to matter Weight: in order to be useful for detecting debris the radar ...


23

There's no real distinction once you're in orbit; a northbound LEO orbit at a given longitude at a given time is a southbound orbit at nearly the opposite longitude 45 minutes later. The rotation of the Earth brings any chosen launch site under the ground track of every polar-orbit satellite, in both directions, daily. Therefore, the choice of northerly or ...


23

To resonate with @Hobbes general characterization: Nibiru is contrived nonsense. Ignoring the fact that previously announced dates for the Earth cataclysm have come and gone with no such mayhem, some adherents to the Nibiru cataclysm theory cling to the possibility that it is planet-sized, but so far out in the solar system that we haven't seen it yet. ...


22

I would say it's probably Envisat. It is definitely the heaviest although i'm not sure if it is also the largest piece volumetrically. We had a full scale 'mock up' at our faculty and I can confirm that it is absolutely massive! They have been thinking about ways to deorbit it for quite a while now since a collision involving this large of a satellite could ...


21

The Lagrange points L1, L2 and L3 are stable in prograde- and retrograde direction, but unstable on the radial axis. That means any object on these points will drift away in radial direction unless it uses small amounts of thrust to balance on these points, so any concentration of natural mass or debris at these points is impossible. Only the points L4 and ...


20

Blockchain is a very poor solution to a specific problem: achieving ledger consensus among a large number of agents when there is substantial incentive to corrupt the record, and the entries in the ledger are directly related to one another. This is not a good fit to a satellite ephemeris. A relatively small number of agents add records to the system at a ...


19

Quoth Robert Frost, self-described as "instructor/engineer in the NASA Mission Operations Directorate": If the object is in LEO and larger than around 10 cm, the ISS can be warned and moved, a few orbits in advance of the potential impact. For smaller objects, they just accept the risk. The ISS has shields called Whipple bumpers. They are multi-...


19

NASA has a decent FAQ section on their website about orbital debris. How many orbital debris are currently in Earth orbit? More than 21,000 orbital debris larger than 10 cm are known to exist. The estimated population of particles between 1 and 10 cm in diameter is approximately 500,000. The number of particles smaller than 1 cm exceeds 100 million. ...


19

To add to other answers, the L1-L2 Lagrange points are unstable because they need to follow radial velocity of the two parent bodies as they orbit each other, in our case the Earth in a heliocentric orbit around the Sun, but none of them are really at the orbital altitude matching their radial velocity (too slow in L1 and too fast in L2). Since the Earth's ...


19

I'll give you an intuitive way to think about it, then a script to play around with if you like. When the spacecraft is at periapsis, it is there, at periapsis. A bit of drag isn't going to change its position by much, but it will change its velocity. The new velocity determines how high it can reach at apoapsis. If it has slowed down, it will climb to a ...


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