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51 votes
Accepted

Are pictures of Earth' space junk realistic?

No, it's entirely unrealistic. The Earth is very large by the standards of what you deal with in day to day life -- it's about 13 million meters in diameter. Satellites are typically only a few meters ...
Russell Borogove's user avatar
36 votes

Are pictures of Earth' space junk realistic?

The "actual data" is that for every one of their dots, there is probably a real debris fragment, the mix of satellites/rocket bodies etc is probably broadly right, and so on. However, the ...
Andrew is gone's user avatar
19 votes
Accepted

How do we know what percentage of NEOs we've discovered?

NEOs are mostly found as dots in images taken by various telescopes, often those of amateurs (as in not paid, nothing about skill or equipment). By taken repeated images days apart moving dots can be ...
GremlinWranger's user avatar
18 votes

Are pictures of Earth' space junk realistic?

We cannot depict the space junk to scale. Neither the human vision, nor modern imaging technology can have both Earth and whatever human-made orbiting object visible at the same scale, without having ...
fraxinus's user avatar
  • 2,519
14 votes
Accepted

Could Starman get ejected from the Solar System?

Definitely - it could be ejected. But Earth would only play a minor role. Starman now counts as a Near Earth Object, being any object crossing Earth's orbit. Any such object is occasionally in Earth'...
kim holder's user avatar
  • 21.4k
14 votes

What asteroids have the least delta-v to reach?

note: This is a historical answer, and explains how to find tiny asteroids close by. The OP has clarified they want a profitably mineable-sized asteroid so there is room for more answers. Previous ...
uhoh's user avatar
  • 149k
10 votes

Do all dangerous asteroids first pass through keyholes?

Dangerous asteroids are those that can hit the Earth, and are large enough to cause substantial damage. There are currently no such known asteroids. (2020-02-21) There are two ways an asteroid could ...
SE - stop firing the good guys's user avatar
7 votes
Accepted

How can uncertainty about the position of an object decrease over time?

I have a couple of guesses, but they're fairly generic, and not closely tuned to this particular case. I have been fiddling around with the ephemeris generation tools on the source page, but I have ...
Ryan C's user avatar
  • 7,972
6 votes
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How will OSIRIS-REx scan and characterise the near-earth asteroid Bennu?

OSIRIS-REx is packed all full of good stuff. I'll throw together a quick list of the scanning ones you're interested in. Also of note is that the entire spacecraft will be making that scanning ...
M.A.H.'s user avatar
  • 1,276
6 votes
Accepted

Have there been any documented mini-moons since 2006 RH120?

Possibly the earliest documented mini-moon was the one associated with the 1913 Great Meteor Procession. After 2006 RH120, that you mentioned, another was identified on October 3, 2015 and designated ...
called2voyage's user avatar
  • 23.7k
6 votes

What asteroids have the least delta-v to reach?

I don't have the time right now to post a comprehensive answer, so I'll do a provisional one with some resources that might help you out. At some point I will might edit this into a full answer. Here'...
Ingolifs's user avatar
  • 6,458
5 votes

Are pictures of Earth' space junk realistic?

The largest human space object in space is the International Space Station, with the largest dimension at some 100 meters. Lets depict that as a 2x2 pixel on a very good display (400 Pixels Per Inch ...
Calin Ceteras's user avatar
5 votes

Earth Live Video Feed in HD?

As far as I know, only NASA (since you asked for the agency) through its High Definition Earth Viewing (HDEV) Experiment gives the live coverage of the Earth from the ISS. It might not be up for all ...
OrangeDurito's user avatar
4 votes
Accepted

Why has the Earth-Sun libration point L1 been chosen over L2 for NEOCam (now NEO Surveyor) to detect new NEOs?

We want to find NEOs that are inside Earth's orbit, like Atens, and telescopes don't like looking close to the Sun. So the more inside the orbit of the Earth you can get, the more new NEOs you will ...
Mark Adler's user avatar
  • 58.2k
3 votes

Has there ever been an instance of asteroid discovery by radar; seen first by radar rather than being observed after optical discovery?

Partial answer to get things moving. While so far I haven't found an asteroid proper that was first observed by radar, there are at least several examples of objects that were first discovered ...
uhoh's user avatar
  • 149k
3 votes
Accepted

Yikes! How did we miss 2017 VL2?

There are estimated to be around 1 million Near Earth Objects (NEOs) of around in the same size as 2017 VL2, of which around 1% are known (see Rusty's Planetary Defense 6-part series). It's only much ...
djr's user avatar
  • 1,705
2 votes

How will OSIRIS-REx scan and characterise the near-earth asteroid Bennu?

For an unrelated purpose, I retrieved the Mission Requirements Document (OSIRIS-REx-RQMT-0001) for OSIRIS-REx. It details the minimum performance requirements for the mission. We can look at ...
Mark Omo's user avatar
  • 5,291
2 votes
Accepted

Why do (did) they think WT1190F is low density?

WT1190F orbited the Earth during the time it was observed. There were a number of varying observations that were made over it's lifetime. Wikipedia shows the lifetime at 3 different years, each with a ...
PearsonArtPhoto's user avatar
  • 121k
2 votes

What is the "interesting story" on the limitations of NASA's current near Earth object survey network"?

For years, wide field infrared orbital telescopes have been touted as the best way to complete a survey of NEO objects and give a greater warning time on potential close approaches. Astronsapper's ...
Terrance Yee's user avatar
  • 2,294
2 votes

Do all dangerous asteroids first pass through keyholes?

Novel keyhole-less asteroids could exist An extrasolar asteroid such as ʻOumuamua would not need to pass through a gravitational keyhole within our solar system, but the odds of a such a collision are ...
Dragon's user avatar
  • 121
1 vote

Are pictures of Earth' space junk realistic?

Wikipedia gives the following estimate for the total number of space debris objects: As of January 2019, more than 128 million pieces of debris smaller than 1 cm (0.4 in), about 900,000 pieces of ...
JonathanReez's user avatar
  • 1,081
1 vote

What is NEOCam's (now NEO Surveyor) strategy for scanning the sky? Need to consider in which coordinate system?

See also: What is the name of the new NEO searching telescope "heavily based on" NEOCam? (now NEO Surveyor) Why has the Earth-Sun libration point L1 been chosen over L2 for NEOCam (now NEO ...
uhoh's user avatar
  • 149k
1 vote
Accepted

Puzzler: Why higher solar phase angle (SPA) allows for many more feasible FastKD (kinetic deflection) communications satellite “hijacking” missions?

I don't understand the orbital mechanics aspects of this statement: higher allowed Solar Phase Angle (SPA) at impact is required to achieve high deflection performance But, interpreting: SPA ...
BrendanLuke15's user avatar
1 vote

Do all dangerous asteroids first pass through keyholes?

The question is a little backwards. When we talk about a "gravitational keyhole", what we mean is we have an object that has a known orbit with some degree of uncertainty, which is going to ...
Darth Pseudonym's user avatar
1 vote

Are the estimated chances of Bennu hitting Earth in the next 200 years still about "1 in 1410" now that OSIRIS REx has scanned it?

Wikipedia covers this. The 1 in 1410 probability comes from Long-term impact risk for (101955) 1999 RQ36 in 2009 which notes... The analysis of impact possibilities so far in the future is ...
Schwern's user avatar
  • 8,016
1 vote
Accepted

What are monostatic radar observations, and how will Deep Space Network's DSS-13 be used to observe asteroid 1999 WK4's flyby of Earth?

Monostatic just means the transmitter and receiver are in the same place (DSS-14), as opposed to bistatic radar where they are separate (DSS-13 transmitter, Green Bank receiver). No klystron means ...
Hobbes's user avatar
  • 128k
1 vote

How will the "fleet of small asteroid hunters" proposed by the B612 Foundation & York Space Systems work?

In theory, a smaller telescope can see a dim object by just looking longer than a larger one. There are issues of noise and stability that limit this, but for small factors it works. So their plan ...
Bob Jacobsen's user avatar
  • 12.7k
1 vote

Could Starman get ejected from the Solar System?

According to this paper, it is unlikely: Hanno Reis, Daniel Tamayo, David Vokrouhlicky. The random walk of cars and their collision probabilities with planets. arXiv:1802.04718: By running a ...
gerrit's user avatar
  • 11.7k

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