Author Topic: 2016 HO3 is a quasi satellite of earth - 40m to 100m Apollo Asteroid  (Read 16621 times)

Offline Ludus

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http://www.jpl.nasa.gov/news/news.php?feature=6537

A unique target for asteroid missions that's a constant companion of earth.

Offline Comga

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Fascinating
Perhaps NASA (or someone else) could do a real Asteroid Rendezvous Mission, instead of fetching a boulder.
It could be an excellent place to practice for a Phobos mission, a practice for the practice for going to Mars
Can someone calculate trajectories to and from this object?
It would seem that there are an infinite number of variations for at least two types of missions, an impulse trajectory with three short firings and continuous thrusting like SEP. 
Mission duration should be selectable with little to no velocity penalty.

Notes from the Arkansas Sky Observatories:

The object has attracted attention for two reasons, both of which are incredibly strange for nearly every object known:

1) the orbit is locked into a very odd figure-8 pattern that does not seem realistic to be either an artificial satellite launched from Earth or a natural satellite of Earth or asteroid.  Taking into consideration [all of the] gravitation and solar forces on the object, this orbital pattern is about as strange as has ever been seen. 

2)  The mass of the object is very low, and indicates that it is NOT natural "space rock" material, very small for its total volume and size.  This, at the outset, would indicate an artificial object like a booster rocket or similar huge object left over from some satellite launch.  Also note that the object appears to be "highly elongated" and spinning rapidly, based on the light variations seen by earth-based telescopes

Thus far, there is no man-made object that NASA is aware of that has been launched of this size, mass and one which would attain such an unusual orbit; further complicatiing things is that the orbit of this unknown object is fairly stable and not subject to orbital "decay"  as one would expect from something launched from Earth.


edit: It would be disappointing, to say the least, to travel ten million kilometers only to find it's space flotsam.
« Last Edit: 06/16/2016 09:51 PM by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Star One

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Looking at that link in the OP in relation to the second link, NASA doesn't seem that baffled by this object?

Is it possible that this object could eventually be shepherded into a more stable orbit around the Earth, not by artificial means but just the Earth's gravitational influence, so it becomes a true satellite.
« Last Edit: 06/16/2016 10:19 PM by Star One »

Offline Ludus

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If this asteroid turns out to be a valuable resource type, it might be a candidate for more ambitious missions to actually gradually move the entire thing to a more convenient location in earth-moon Lagrange or lunar orbit.

Controlled movement of something that massive would probably require tech like a solar powered mass driver rail gun with an automated drilling system to feed it mass.

I bet Planetary Resources has been looking at this one for awhile already.

Offline TomH

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I saw this on WaPo Thur. morning, but didn't have time to post here. At its nearest, it is about 9M mi. away. I would much prefer an Orion visit to this object than to haul some VW sized rock back from elsewhere. Take a Bigelow hab and actually go somewhere.

Offline ChrisWilson68

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It would be disappointing, to say the least, to travel ten million kilometers only to find it's space flotsam.

Unless it's flotsam that's not human-made. :-)

Offline Bynaus

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Its a cool discovery. It would be interesting to know if there are realistic trajectories to reach it with a manned mission (e.g., with Orion or Dragon 2). Given its substantial inclination, I can imagine that there might be other objects which are more accessible in terms of delta-v.

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1) the orbit is locked into a very odd figure-8 pattern that does not seem realistic to be either an artificial satellite launched from Earth or a natural satellite of Earth or asteroid.  Taking into consideration [all of the] gravitation and solar forces on the object, this orbital pattern is about as strange as has ever been seen. 

Strange claim. This "figure 8 pattern" is only a projection of the orbit onto the Earth's night sky. If you look at the video in the OP link, its a perfectly normal elliptical orbit around the sun. It just happens to be one slightly perturbed by the Earth in a way such that it keeps the Earth company.

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2)  The mass of the object is very low, and indicates that it is NOT natural "space rock" material, very small for its total volume and size.

Even more strange claim. I strongly doubt anyone has been able to measure the mass of this object.

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further complicatiing things is that the orbit of this unknown object is fairly stable and not subject to orbital "decay"  as one would expect from something launched from Earth.

Orbital decay (for satellites) is not a consequence of having been launched from Earth. Its a function of the number of atoms (from the extended atmosphere) encountered by a satellite on its orbital path, and the resulting "drag" force slowing it down. This effect (which applies to natural and artificial objects equally, of course) is important for the first 1000 km or so, and negligible on human time-scales above that. As this new asteroid is even further away than that (way beyond the Moon's orbit), this is a complete non-issue here.

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Is it possible that this object could eventually be shepherded into a more stable orbit around the Earth, not by artificial means but just the Earth's gravitational influence, so it becomes a true satellite.

It would need to shed some orbital energy for that. Its not impossible, considering e.g. scenarios involving repeated swing-bys with the Moon, but its not very likely. Exemplified by the fact that neither the Earth, nor the other terrestrial planets seem to have such "captured" small satellites.

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If this asteroid turns out to be a valuable resource type, it might be a candidate for more ambitious missions to actually gradually move the entire thing to a more convenient location in earth-moon Lagrange or lunar orbit.

At 40-100 m, its likely to be not worth the effort. Perhaps for fuel, if its volatile-rich, or rare metals, if its an iron. Both are relatively unlikely, at ca. 15% and ca. 2%, respectively. Of course, its viability as a resource will also depend on the delta-v needed to reach it.

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I bet Planetary Resources has been looking at this one for awhile already.

It has only been discovered in April this year. I doubt PR knew about it before anyone else.
« Last Edit: 06/17/2016 06:20 AM by Bynaus »

Offline Star One

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Its a cool discovery. It would be interesting to know if there are realistic trajectories to reach it with a manned mission (e.g., with Orion or Dragon 2). Given its substantial inclination, I can imagine that there might be other objects which are more accessible in terms of delta-v.

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1) the orbit is locked into a very odd figure-8 pattern that does not seem realistic to be either an artificial satellite launched from Earth or a natural satellite of Earth or asteroid.  Taking into consideration [all of the] gravitation and solar forces on the object, this orbital pattern is about as strange as has ever been seen. 

Strange claim. This "figure 8 pattern" is only a projection of the orbit onto the Earth's night sky. If you look at the video in the OP link, its a perfectly normal elliptical orbit around the sun. It just happens to be one slightly perturbed by the Earth in a way such that it keeps the Earth company.

Quote
2)  The mass of the object is very low, and indicates that it is NOT natural "space rock" material, very small for its total volume and size.

Even more strange claim. I strongly doubt anyone has been able to measure the mass of this object.

Quote
further complicatiing things is that the orbit of this unknown object is fairly stable and not subject to orbital "decay"  as one would expect from something launched from Earth.

Orbital decay (for satellites) is not a consequence of having been launched from Earth. Its a function of the number of atoms (from the extended atmosphere) encountered by a satellite on its orbital path, and the resulting "drag" force slowing it down. This effect (which applies to natural and artificial objects equally, of course) is important for the first 1000 km or so, and negligible on human time-scales above that. As this new asteroid is even further away than that (way beyond the Moon's orbit), this is a complete non-issue here.

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Is it possible that this object could eventually be shepherded into a more stable orbit around the Earth, not by artificial means but just the Earth's gravitational influence, so it becomes a true satellite.

It would need to shed some orbital energy for that. Its not impossible, considering e.g. scenarios involving repeated swing-bys with the Moon, but its not very likely. Exemplified by the fact that neither the Earth, nor the other terrestrial planets seem to have such "captured" small satellites.

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If this asteroid turns out to be a valuable resource type, it might be a candidate for more ambitious missions to actually gradually move the entire thing to a more convenient location in earth-moon Lagrange or lunar orbit.

At 40-100 m, its likely to be not worth the effort. Perhaps for fuel, if its volatile-rich, or rare metals, if its an iron. Both are relatively unlikely, at ca. 15% and ca. 2%, respectively. Of course, its viability as a resource will also depend on the delta-v needed to reach it.

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I bet Planetary Resources has been looking at this one for awhile already.

It has only been discovered in April this year. I doubt PR knew about it before anyone else.

I thought Mars's moons were captured asteroids from the asteroid belt?

Also will this object be given a proper name being as it is a semi-satellite of Earth now and for a number of centuries beyond?
« Last Edit: 06/17/2016 12:40 PM by Star One »

Offline Bynaus

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I thought Mars's moons were captured asteroids from the asteroid belt?

Not necessarily. If they are, it is very strange that they orbit within the equatorial plane of Mars, on circular orbits. This is why some people think they might have been formed by a Giant Impact on Mars.

The gas giants do have some satellites which were captured (the irregular satellites of Jupiter, e.g.), but these circle their planets on eccentric, inclined orbits.

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Also will this object be given a proper name being as it is a semi-satellite of Earth now and for a number of centuries beyond?

Its not really a satellite. its "orbit" is far beyond the Hill sphere, so it is always in a region of space where the sun's gravity dominates of the Earth's. Its near 1:1 resonance with Earth protects it from encounters with the planet, so its orbit is long-term stable. That said, it is possible that it will get a proper name, eventually, if the discoverers put some effort into it. Although it will be an asteroid designation, like, e.g., 99942 Apophis or 3753 Cruithne.

Offline JasonAW3

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It would be disappointing, to say the least, to travel ten million kilometers only to find it's space flotsam.

Unless it's flotsam that's not human-made. :-)

At a size of between 130 to 325 feet, It'd be a pretty safe bet that it ain't one of ours.

      If memory serves, we haven't sent anything with a length or breadth of greater than 130 feet, outside of low Earth orbit.  While it's likely to be some natural object, the forces involved in its' orbit, seem to make that highly unlikely to be of natural origin.  at 325 feet, it would be large enough to be a fairly sizable space station, possibly even a toroid type.  It's likely natural, but its' characteristics do seem a bit suspicious.
My God!  It's full of universes!

Offline knotnic

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Its a cool discovery. It would be interesting to know if there are realistic trajectories to reach it with a manned mission (e.g., with Orion or Dragon 2). Given its substantial inclination, I can imagine that there might be other objects which are more accessible in terms of delta-v.

...

First, thanks Bynaus for all your insightful comments, they are spot on about about what is known about this item.

Regarding delta-v and accessibility, there are certainly others with better specific launch opportunities, but in terms of total viable opportunities it's pretty high on the list NHATS shows a large number of viable round-trips for <7km/s from LEO to re-entry, with the lowest energy ones taking about a year.  It can be done even quicker, coming down to <200 days if you can come up with 11+ km/s.  What's pretty unique about this due to its quasi-stable relationship with earth is that the windows are open very consistently, for many years, rather than every few years or more as for other low delta-V NEOs. 

Spectral and other data will tell if it's a particularly interesting object or not, and improve size constraints if they can get the right IR data - and perhaps radar can tell if it has companions (which would allow one to determine its mass; I'm not sure why it's shown as not observable from Goldstone or Arecibo, since it reaches a decent declination and pointing uncertainty is low) - but for flexibility and ease of targeting it may be quite attractive.


Offline Bynaus

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While it's likely to be some natural object, the forces involved in its' orbit, seem to make that highly unlikely to be of natural origin.

I am not sure how you come to that conclusion. There are no "forces" involved apart from gravity (essentially).

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Regarding delta-v and accessibility, there are certainly others with better specific launch opportunities, but in terms of total viable opportunities it's pretty high on the list.  NHATS shows a large number of viable round-trips for <7km/s from LEO to re-entry, with the lowest energy ones taking about a year.

That is pretty interesting - thanks! One year round-trip should be doable, in principle (remember the one-year ISS mission). 7 km/s is roughly what a refueled F9 upper stage could give you (there are obviously problems with that specific scenario, but just as a reference).

You are right that the fact that the window is basically open all the time is a very attractive feature.

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Spectral and other data will tell if it's a particularly interesting object or not, and improve size constraints if they can get the right IR data - and perhaps radar can tell if it has companions (which would allow one to determine its mass; I'm not sure why it's shown as not observable from Goldstone or Arecibo, since it reaches a decent declination and pointing uncertainty is low) - but for flexibility and ease of targeting it may be quite attractive.

I am looking forward to spectral data. Chances are its a boring S or Q type... But one can always hope to get lucky.

Regarding companions, very small objects tend to have Hill spheres smaller than their radii. Say its 50 m diameter and has a density of 2 g/cm3. Then, its mass is about 131'000 tons, and its Hill sphere is only 4 km wide. That should still allow a satellite, but it would be (to my knowledge) the smallest object we know of with a satellite. Without a satellite, determining the mass would likely require sending a space probe.
« Last Edit: 06/17/2016 03:34 PM by Bynaus »

Offline Proponent

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At a size of between 130 to 325 feet, It'd be a pretty safe bet that it ain't one of ours.

I'll bet that size is based largely on brightness, though.  If's painted white, it's probably smaller than the typical asteroid of similar brightness.

Offline Nilof

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I suggest we call this asteroid "Minmus".   ;)

Also, I'm a bit puzzled by the orbit from thinking in term of the Jacobi integral, but I guess that's because I don't have a good intuition for quasisatellites with high relative inclinations. However, it looks like the perfect target for a BLEO asteroid randezvous mission that can act as a precursor for a moons of mars mission.
« Last Edit: 06/17/2016 04:10 PM by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline JasonAW3

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At a size of between 130 to 325 feet, It'd be a pretty safe bet that it ain't one of ours.

I'll bet that size is based largely on brightness, though.  If's painted white, it's probably smaller than the typical asteroid of similar brightness.

That maybe, but it would still have to be pretty sizable to be that reflective at the distances involved.

     I'd be very interested to see if any large spent stages could be linked to this object.  I suspect that it'd almost HAVE to be one of the Saturn V's upper stages.  If not, I don't know of anything else man made that would come close to the minimum size estimated for this object.

     Again, likely a rock, but a pretty weird one.  (Kind of hope it's a high density carbon based asteroid.  Then we could name it Lucy.  As in "Lucy In The Sky With Diamonds"...  Yeah, I'll see my own way out now...)
     I look forward to the radar images we get, when they do image it, as that should give us a better idea of its' structure and shape.
My God!  It's full of universes!

Offline CNYMike

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It would be disappointing, to say the least, to travel ten million kilometers only to find it's space flotsam.

Unless it's flotsam that's not human-made. :-)

And if it is human made, it's the first space salvage mission. 
"I am not A big fat panda.  I am THE big fat panda." -- Po, KUNG FU PANDA

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Offline Comga

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I thought Mars's moons were captured asteroids from the asteroid belt?

There is another NEO, currently on a ~0.99 year orbit, discovered in the late 90's, that modeling shows enters a pseudo-orbit about the Earth like that for 2016 HO3 every few centuries, and staying there for decades before resuming its century long horseshoe path relative to the Earth.

Does anyone know how the size was determined?  Most size calculations use the measured brightness with an assumed albedo, like Proponent said.  It seems too far to measure with radar, and it's slow motion on the sky decreases the probability of useful stellar occultations.

knotnic:  I really like that NHATS page.  >3 million trajectories calculated through 2040.  Minimum mission duration 330 days with 7.0 km/sec delta V.  That sounds doable.  (NHATS says it is never close enough for radar observations.)

edit:  NHATS shows that there is an opportunity with a duration of ~350 days and a delta V below 8 km/sec once a year.  The mission doesn't have to wait until the "best" trajectory leaving Jan 3, 2029.  That's a "soft minimum".
« Last Edit: 06/17/2016 05:57 PM by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Star One

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I am further confused on this issue when I read in a couple of articles reporting this news that the Earth already has a number of mini-moons, but it was stated up thread that the rocky planets don't collect such moons?
« Last Edit: 06/17/2016 05:58 PM by Star One »

Offline Bynaus

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Again, likely a rock, but a pretty weird one.

Why? Its an asteroid. Sure, its on a somewhat exceptional orbit, but apart from that there is nothing - to my knowledge - that would make it particularly weird.

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Does anyone know how the size was determined?  Most size calculations use the measured brightness with an assumed albedo, like Proponent said.

We only know the brightness. Size then depends on albedo, like you say, and the size range is a reflection of a resonable range of albedos (typically 0.05 to 0.3 or so). So it could be bigger / smaller than the indicated range if it has an exceptionally low / high albedo.

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I am further confused on this issue when I read in a couple of articles reporting this news that the Earth already has a number of mini-moons, but it was stated up thread that the rocky planets don't collect such moons?

There is a difference here: the irregular satellites of the giant planets are permanently bound. Their orbital energy with respect to their parent planet is negative. On the other hand, "mini moons", "quasi-satellites", "temporary captured orbiters" etc are not permanently bound to Earth - their orbital energy with respect to the Earth is postive. It is just a geometric conincidence combined with the subtle interplay of the gravity fields of the Earth and the sun that allows these kinds of special configurations. As mentioned above, these objects would all need to shed some of their energy to remain permanently within Earth's gravity well, which is unlikely to happen except under special circumstances.
« Last Edit: 06/17/2016 07:06 PM by Bynaus »

Offline TrevorMonty

Its a cool discovery. It would be interesting to know if there are realistic trajectories to reach it with a manned mission (e.g., with Orion or Dragon 2). Given its substantial inclination, I can imagine that there might be other objects which are more accessible in terms of delta-v.

...

First, thanks Bynaus for all your insightful comments, they are spot on about about what is known about this item.

Regarding delta-v and accessibility, there are certainly others with better specific launch opportunities, but in terms of total viable opportunities it's pretty high on the list NHATS shows a large number of viable round-trips for <7km/s from LEO to re-entry, with the lowest energy ones taking about a year.  It can be done even quicker, coming down to <200 days if you can come up with 11+ km/s.  What's pretty unique about this due to its quasi-stable relationship with earth is that the windows are open very consistently, for many years, rather than every few years or more as for other low delta-V NEOs. 

Spectral and other data will tell if it's a particularly interesting object or not, and improve size constraints if they can get the right IR data - and perhaps radar can tell if it has companions (which would allow one to determine its mass; I'm not sure why it's shown as not observable from Goldstone or Arecibo, since it reaches a decent declination and pointing uncertainty is low) - but for flexibility and ease of targeting it may be quite attractive.
Staging from EML1 or 2 would enable the 200day trip for 7-8km/s.

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