Author Topic: 2016 HO3 is a quasi satellite of earth - 40m to 100m Apollo Asteroid  (Read 18857 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.

Online 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.

Online 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.

Quote
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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Online 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 »

Online 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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Offline Nilof

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A small-ish SEP spacecraft should be able to do the mission in less than 200 days as well if it got to start at EML2. At 100 days and 1 mm/s acceleration it could get in about 8600 m/s delta-v, and the parts that take delta-v in the chemical mission after leaving Earth's gravity well is all stuff that would get no Oberth benefit whatsoever.
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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I think that we're kind of putting the cart before the horse at this point.

     While it would be great to send a probe to this object, it's probably be best if we get better images and radar pictures of this thing to determine if we WANT to spend billions to send a probe or ARM mission to it in the first place.
My God!  It's full of universes!

Offline MP99

What sort of image could we expect from Hubble of this object?

Cheers, Martin

Offline Nilof

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What sort of image could we expect from Hubble of this object?

Cheers, Martin

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.
« Last Edit: 06/18/2016 12:16 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 edkyle99

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Even more strange claim. I strongly doubt anyone has been able to measure the mass of this object.
Of course they have.
http://www.scientificamerican.com/article/how-do-scientists-measure/

 - Ed Kyle

Online jgoldader

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Even more strange claim. I strongly doubt anyone has been able to measure the mass of this object.
Of course they have.
http://www.scientificamerican.com/article/how-do-scientists-measure/

 - Ed Kyle

The OP was asking about THIS object, and since we haven't had a spacecraft near it, there's nothing for it to perturb gravitationally to get a mass.  What you'd do is figure a few 1000 kg/m^3 density, give a factor of 2 uncertainty (mostly on the low side in case it's like Mathilde).  Given the uncertainty in the size, there's probably about a factor of 10 uncertainty in mass right now.  I suspect the size can be measured pretty accurately by radar from the intensity of a reflected signal.

Given that Congress seems to want to kill ARRM, it would probably be more useful to think of a low-cost way to get a probe to the asteroid.  The Japanese Procyon would likely be a good departure point for a design, but of course its SEP failure would have to be diagnosed and remedied.
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Offline Geron

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Why not Dragon asteroid 2017 as a Mars mission precursor!?

Offline edkyle99

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Even more strange claim. I strongly doubt anyone has been able to measure the mass of this object.
Of course they have.
http://www.scientificamerican.com/article/how-do-scientists-measure/

 - Ed Kyle

The OP was asking about THIS object, and since we haven't had a spacecraft near it, there's nothing for it to perturb gravitationally to get a mass.  What you'd do is figure a few 1000 kg/m^3 density, give a factor of 2 uncertainty (mostly on the low side in case it's like Mathilde).  Given the uncertainty in the size, there's probably about a factor of 10 uncertainty in mass right now.  I suspect the size can be measured pretty accurately by radar from the intensity of a reflected signal.

Given that Congress seems to want to kill ARRM, it would probably be more useful to think of a low-cost way to get a probe to the asteroid.  The Japanese Procyon would likely be a good departure point for a design, but of course its SEP failure would have to be diagnosed and remedied.
If the orbit is known, the mass is known.

 - Ed Kyle

Offline MP99

What sort of image could we expect from Hubble of this object?

Cheers, Martin

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.
Many thanks.

Cheers, Martin

Online jgoldader

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The OP was asking about THIS object, and since we haven't had a spacecraft near it, there's nothing for it to perturb gravitationally to get a mass.  What you'd do is figure a few 1000 kg/m^3 density, give a factor of 2 uncertainty (mostly on the low side in case it's like Mathilde).  Given the uncertainty in the size, there's probably about a factor of 10 uncertainty in mass right now.  I suspect the size can be measured pretty accurately by radar from the intensity of a reflected signal.

If the orbit is known, the mass is known.

 - Ed Kyle

How?  The moons of the outer planets were used to find the planets' masses using Kepler's third law.  It's a standard introductory astronomy exercise.  Knowing the orbit of an object around the Sun, for example, can tell you the mass of the Sun, but not the object itself, unless the mass of the smaller object is great enough to cause a measurable reflex motion of the Sun.  The mass of this tiny rock is utterly insignificant compared to the mass of the Sun.
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Offline dror

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What sort of image could we expect from Hubble of this object?

Cheers, Martin

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.

What sort of image could we expect from JWST of this object?
"If we crave some cosmic purpose, then let us find ourselves a worthy goal. "
Carl Sagan, Pale Blue Dot

Online Comga

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Even more strange claim. I strongly doubt anyone has been able to measure the mass of this object.
Of course they have.
http://www.scientificamerican.com/article/how-do-scientists-measure/

 - Ed Kyle
That article specifically EXCLUDES 2016 HO3.
It does not have a satellite from which to calculate the mass.
It is WAY too small to perturb the orbits of any other body.
No probe has flown by it to be deflected by its gravity.

Extended observation of the orbit can bound the non-Keplarian nature, that is, how solar wind and light pressures affect the orbit.  That can yield an approximation of density, or "ballistic coefficient", kg/m^2.
If one then has the size, one can estimate the mass.
But..

All the evidence for size is the brightness, distance, distance to the sun, and an assumed albedo. (reflectivity)
One can use the albedo measured for known asteroids, but the resulting values say that 2016 HO3 is not like previously observed asteroids.   

NHATS says that it is too far for radar measurements.
It's too faint for most spectral measurements.
It is too faint to measure by observing a stellar occultation, which is unlikely in any case. 

It's not clear how much we can learn about it without going there.

No one will plan a crewed mission without SOME reconnaissance before hand.
Getting a reconnaissance mission approved and funded is a big challenge, as are all proposed missions.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Nilof

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What sort of image could we expect from Hubble of this object?

Cheers, Martin

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.

What sort of image could we expect from JWST of this object?

JWST is bigger, but it's also restricted to longer wavelengths so its maximum resolution should still be >4 km. You'd need a diffraction limited telescope with a 100m main mirror (or an interferometer with a baseline of that magnitude) to resolve this asteroid. For pretty pictures, sending something close to it is the only real option.

Communication requirements for a spacecraft should be pretty lenient though. It shouldn't need a dedicated DSN dish. A mission to it could be great for a new laser communications tech demonstrator since the distance is significantly larger than Earth-Moon but well smaller than Earth-Mars.
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 Donosauro

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How the sizes of asteroids too small to resolve are estimated:
http://www.nasa.gov/mission_pages/WISE/multimedia/gallery/neowise/pia14733.html

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Dawn is a likely spacecraft of which a copy would be appropriate for a mission to 2016 HO3.  It was capable of ~10 km/sec delta V, and had a visible "framing" camera, a visible and near IR spectrometer, and the Gamma Ray and Neutron Detector (GRaND). 
It cost about a half billion dollars a decade ago. 

OSIRIS-REx is another.  It includes even more instrumentation and TAGSAM, the Touch and Go Sample Acquisition Mechanism.  However it doesn't have much propulsion and is costing about one billion dollars.

Such a mission would have to compete with other Discovery or New Frontiers class planetary missions, of which there are several.

It doesn't seem appropriate for laser communications because there just wouldn't be that much data to send back.  Mapping the surface at 1 cm resolution would take ~1GB.
« Last Edit: 06/18/2016 08:16 PM by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online Comga

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How the sizes of asteroids too small to resolve are estimated:
http://www.nasa.gov/mission_pages/WISE/multimedia/gallery/neowise/pia14733.html

It's really faint.
Which telescopes could observe 2016 HO3 in the thermal infrared?
WISE is no longer doing thermal infrared observations, and it is not clear that 2016 HO3 ever went across WISE's line of sight, given the odd orbit, or that it could be seen by WISE. 
(Wise expanded the population of <1km NEOs, but how many <0.1 km NEOs did it find?)
Does it get far enough from the Sun to allow JWST to look at it, when JWST launches and IF observing 2016 HO3 successfully competed for observing time?
« Last Edit: 06/18/2016 08:18 PM by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Donosauro

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How the sizes of asteroids too small to resolve are estimated:
http://www.nasa.gov/mission_pages/WISE/multimedia/gallery/neowise/pia14733.html

It's really faint.
Which telescopes could observe 2016 HO3 in the thermal infrared?
WISE is no longer doing thermal infrared observations, and it is not clear that 2016 HO3 ever went across WISE's line of sight, given the odd orbit, or that it could be seen by WISE. 
(Wise expanded the population of <1km NEOs, but how many <0.1 km NEOs did it find?)
Does it get far enough from the Sun to allow JWST to look at it, when JWST launches and IF observing 2016 HO3 successfully competed for observing time?

I don't know. I am not an expert on the technique. http://www.diss.fu-berlin.de/diss/servlets/MCRFileNodeServlet/FUDISS_derivate_000000001521/04_Chapter2.pdf?hosts=
says: "With modern medium infrared instrumentation, equipping the largest existing telescopes, it is possible to measure the weak thermal infrared emission of NEOs, down to sizes of the order of some hundred meters."

Offline MP99

Perhaps this could be suitable for a BEO cubesat mission.

Duration should be reasonably short, distance for communicating back is fairly low. No issue with distance from the Sun for solar panels. Flyby would give useful info, and might not have to be at huge speed (depending on SC lifetime).

Cheers, Martin

Online Comga

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Perhaps this could be suitable for a BEO cubesat mission.

Duration should be reasonably short, distance for communicating back is fairly low. No issue with distance from the Sun for solar panels. Flyby would give useful info, and might not have to be at huge speed (depending on SC lifetime).

Cheers, Martin

A big problem is propulsion
It is safe to assume that the delta-V in the NHATS models is equally distributed among the three.
That means the flyby needs ~2.5 km/sec.
That's a lot of propulsion
Cubesats rarely have any, and none have had 1% of this.  And you know the tyranny of the rocket equation.
And no cubesats have had high Isp SEP.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Robotbeat

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What sort of image could we expect from Hubble of this object?

Cheers, Martin

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.

What sort of image could we expect from JWST of this object?

JWST is bigger, but it's also restricted to longer wavelengths so its maximum resolution should still be >4 km. You'd need a diffraction limited telescope with a 100m main mirror (or an interferometer with a baseline of that magnitude) to resolve this asteroid. For pretty pictures, sending something close to it is the only real option.
...
...so I wonder if any of these would work for resolving the size:
https://en.wikipedia.org/wiki/List_of_astronomical_interferometers_at_visible_and_infrared_wavelengths

...what's the apparent magnitude of 2016 HO3?
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Online A_M_Swallow

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Perhaps this could be suitable for a BEO cubesat mission.

Duration should be reasonably short, distance for communicating back is fairly low. No issue with distance from the Sun for solar panels. Flyby would give useful info, and might not have to be at huge speed (depending on SC lifetime).

Cheers, Martin

A big problem is propulsion
It is safe to assume that the delta-V in the NHATS models is equally distributed among the three.
That means the flyby needs ~2.5 km/sec.
That's a lot of propulsion
Cubesats rarely have any, and none have had 1% of this.  And you know the tyranny of the rocket equation.
And no cubesats have had high Isp SEP.

Currently no cubesats have high Isp SEP.

However
"With a ~2U package (including 300cc/1.5kg iodine propellant), the {BUSEK} BIT - 3 system can provide 3km/s delta-V to a 6U/12kg CubeSat."
http://www.nasa.gov/sites/default/files/files/Vlad_Busek_Iodine_RF_Ion_Thruster.pdf

This is one of the thrusters in the Technology Development Project Selections announced on September 4, 2013. These should be available soon and in need of a mission (unless they were cancelled).
http://www.nasa.gov/content/technology-development-project-selections/#.V2YKmDVaHIV

Offline Donosauro

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What sort of image could we expect from Hubble of this object?

Cheers, Martin

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.

What sort of image could we expect from JWST of this object?

JWST is bigger, but it's also restricted to longer wavelengths so its maximum resolution should still be >4 km. You'd need a diffraction limited telescope with a 100m main mirror (or an interferometer with a baseline of that magnitude) to resolve this asteroid. For pretty pictures, sending something close to it is the only real option.
...
...so I wonder if any of these would work for resolving the size:
https://en.wikipedia.org/wiki/List_of_astronomical_interferometers_at_visible_and_infrared_wavelengths

...what's the apparent magnitude of 2016 HO3?

Its apparent magnitude should be about 19 when the object is closest to earth, if I did the math right. So it looks like none of the existing interferometers are up to the task.
« Last Edit: 06/19/2016 04:35 AM by Donosauro »

Offline MP99

Perhaps this could be suitable for a BEO cubesat mission.

Duration should be reasonably short, distance for communicating back is fairly low. No issue with distance from the Sun for solar panels. Flyby would give useful info, and might not have to be at huge speed (depending on SC lifetime).

Cheers, Martin

A big problem is propulsion
It is safe to assume that the delta-V in the NHATS models is equally distributed among the three.
That means the flyby needs ~2.5 km/sec.
That's a lot of propulsion
Cubesats rarely have any, and none have had 1% of this.  And you know the tyranny of the rocket equation.
And no cubesats have had high Isp SEP.
Thanks. You're right - I was thinking about this more like a standard NASA probe, where the launcher u/s pushes the stage beyond escape, rather than it having to do the injection itself.

But, of course, the point with such a small sat is either to be a secondary, or to launch on a dedicated smallsat launcher, and who's offering a BLEO smallsat launcher?

OTOH, such a sat as secondary on a Super Synchronous Transfer mission could be taken pretty close to escape. Whether that would put it anywhere close to the right vector for transfer is a separate question.

Secondary thought - if the u/s has any residuals after SSTO injection for a disposal burn, that could well go to escape, anyway?

In terms of suitable launchers, Atlas V has dial-a-rocket with options for number of solids, and F9 usually seems to be launching close to its limits on Super Synchronous injections. This would only be possible for very small primary payloads, or FH?

Cheers, Martin


Offline Nilof

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Or you can ensure that the payload has enough delta-v to get to the asteroid without a perfect boost like PR's planned spacecraft. This asteroid should be accessible to an Arkyd 200.
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.

Online Space Ghost 1962

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As to determining if its artificial or not, radar pulse shape, even at that distance, can tell a metallic "skin reflection", once corrected for the medium and distance dispersion relationships.

The fact that the solar wind doesn't perturb it much (hundreds of years stability) suggests a high density.

Since it is close for such a body, if it were to be in the plane of something like Arecibo's dish (assuming it has budget for this), you could pump enough RF to get a scattering profile, and ramp the frequency to see if it matched any of the three major profiles for asteroids, as a gross estimate of WTF this thing is (e.g. a compact dense carbonaceous/nickle-iron/siliceous). If it was a comet fragment, it would already have an emission spectrum and somebody could tell that even with a earth based scope with a high sensitivity / low dispersion CCD spectrum.

As to how you'd get something into such an orbit, it would likely be from debris from the Earth or Moon, either from formation or as part of a collision, where such escaped but not by much, and by accident entered a weak stability region between the Earth Moon Sun ensemble, staying there ever since.

The most interesting part of this is "how long" has it been there? During the formation of the solar system, much has been swept away, so if it has been there a long time, why wasn't it dislodged?

If it hasn't been there long, the capture event would be unique, and likely the result (again) of an encounter.

As to visiting it, a lunar encounter with a phased entry into the same gravitational equipotential would be the obvious choice, like entering a Lissajous orbit. If your US were long lived enough for a post lunar burn you could save much time (down to a few months), but if we're being economical, a hundred kilogram SEP craft that shared a GTO-1800 ride as a secondary might make it in a few years or less, depending on launch and if you could coax a third burn post primary payload, and the moon's position. Such a mission would take longer to design/fund/build/launch then to fly ;)

added:
link to scattering study
« Last Edit: 06/20/2016 12:46 AM by Space Ghost 1962 »

Offline Nullset

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My family is having a good laugh imagining that this object is actually the lid from Operation Plumbob Pascal-B test.
Especially after we read that "calculations indicate 2016 HO3 has been a stable quasi-satellite of Earth for almost a century".   :o

Offline Robotbeat

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What sort of image could we expect from Hubble of this object?

Cheers, Martin

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.

What sort of image could we expect from JWST of this object?

JWST is bigger, but it's also restricted to longer wavelengths so its maximum resolution should still be >4 km. You'd need a diffraction limited telescope with a 100m main mirror (or an interferometer with a baseline of that magnitude) to resolve this asteroid. For pretty pictures, sending something close to it is the only real option.
...
...so I wonder if any of these would work for resolving the size:
https://en.wikipedia.org/wiki/List_of_astronomical_interferometers_at_visible_and_infrared_wavelengths

...what's the apparent magnitude of 2016 HO3?

Its apparent magnitude should be about 19 when the object is closest to earth, if I did the math right. So it looks like none of the existing interferometers are up to the task.
I checked your math, and it looks about right.

But we may build interferometers that work up to 19 magnitude. We have some extremely large telescopes coming online, and we may start building interferometers with large baselines using them. Also, fringe-tracking is improving the limiting magnitude of these interferometers.

...but it'll be a while.
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To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online Comga

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Currently no cubesats have high Isp SEP.

However
"With a ~2U package (including 300cc/1.5kg iodine propellant), the {BUSEK} BIT - 3 system can provide 3km/s delta-V to a 6U/12kg CubeSat."
http://www.nasa.gov/sites/default/files/files/Vlad_Busek_Iodine_RF_Ion_Thruster.pdf

This is one of the thrusters in the Technology Development Project Selections announced on September 4, 2013. These should be available soon and in need of a mission (unless they were cancelled).
http://www.nasa.gov/content/technology-development-project-selections/#.V2YKmDVaHIV

That's a great presentation.  I had forgotten about Busek.  They are making great progress and proposing a mission quite like one to 2016 HO3, although possibly easier to reach.  It requires less delta-V, albeit possibly one launch window instead of 2016 HO3's yearly window. 

A great advantage of cubesats are their standardization and low cost, for both hardware and launch.  Asteroid rendezvous could use a standardized spacecraft.  A second mission would be even more economical than the first.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online TrevorMonty

The new small LVs in development may just be able to deliver a cubesat or two to earth escape velocity. If Moon express MX1e can land on moon using Electron LV, then cut down version of MX1e could give a 6U cubesat around 6km/s.

Offline Bynaus

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The fact that the solar wind doesn't perturb it much (hundreds of years stability) suggests a high density.

That would be (kinda, see below) true if that stability had been observed. It hasn't, of course, because we only found it two months ago. Instead, the stability is inferred from modelling its movement in an n-body integrator over some time. I doubt that this integration even considered non-gravitational effects (because this would require additional knowledge about the object we don't have).

Also, solar wind is negligible on that scale. What you mean are Yarkovsky/YORP effects. Although I doubt they will have much of an effect over the scale of centuries.

Quote
Since it is close for such a body

Its distance to us doesn't depend on its size/density. Its distance to Earth comes from its movement around the sun. In fact, its the other way around: its size depends on the observed brightness, the observed distance, and the assumed albedo. If we were to get the thermal emission, we could calculate the likely size (although thats not perfect either).

Quote
As to how you'd get something into such an orbit, it would likely be from debris from the Earth or Moon, either from formation or as part of a collision, where such escaped but not by much, and by accident entered a weak stability region between the Earth Moon Sun ensemble, staying there ever since.

An ejection from the Moon is a possibility (which has been suggested before for a peculiar NEO, 2000 SG344). Or, it might just be a normal asteroid that was diverted into that orbit by a close encounter with Earth and/or the Moon. Over long time-scales and many trials, even unlikely things are bound to happen eventually.

Quote
The most interesting part of this is "how long" has it been there? During the formation of the solar system, much has been swept away, so if it has been there a long time, why wasn't it dislodged?

Since the stability of its current orbit is on the order of centuries, its a safe bet that it has been in that orbit "on the order of centuries". Before that (and after that), it likely came from (and will go back to) the NEO population.
« Last Edit: 06/20/2016 06:07 AM by Bynaus »

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Magnitude per JPL Horizons won't get brighter than recently, in the near future won't get brighter than ~22nd mag.  Might change with better obs but going on prior results it's hard to find.

See attached for plot of predicted mag and distance.  Later it gets closer again but phase angle is worse.

« Last Edit: 06/20/2016 09:14 PM by knotnic »

Offline Robotbeat

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Magnitude per JPL Horizons won't get brighter than recently, in the near future won't get brighter than ~22nd mag.  Might change with better obs but going on prior results it's hard to find.

See attached for plot of predicted mag and distance.  Later it gets closer again but phase angle is worse.
Nice!
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Offline robertinventor

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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. 

Thought you all might like a link to the original source of this. It's a very strange orbit indeed. Always roughly in the direction of Leo / Virgo, in a figure of eight orbit as seen from Earth - so sometimes closer to the sun, sometimes further away but always in roughly the same absolute direction from Earth. It's very accessible from Earth, in terms of delta v anyway if not bothered about the duration - seems to be slightly easier to reach than the EML2 for its minimum energy orbit and slightlier easier to reach than the Moon for the minimal duration orbit. See delta v table
« Last Edit: 06/21/2016 12:36 PM by robertinventor »

Offline Danderman

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If a commercial enterprise is going to send a prospector out to this object, their discoveries need to be protected, and so I have put together bullet points for a Federal mining claims registry:

http://forum.nasaspaceflight.com/index.php?topic=39504.msg1552399#msg1552399

This would allow a company like PR or DSI to explore a celestial object, and if they find any valuable minerals or ice, their discoveries would be protected like a patent, which could be subsequently assigned (sold) to other companies. Your feedback on the structure of the mining claims registry would be greatly appreciated, in that thread. Please do not waste our time debating about property claims.


Offline Hop_David

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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. 

Thought you all might like a link to the original source of this. It's a very strange orbit indeed. Always roughly in the direction of Leo / Virgo, in a figure of eight orbit as seen from Earth - so sometimes closer to the sun, sometimes further away but always in roughly the same absolute direction from Earth. It's very accessible from Earth, in terms of delta v anyway if not bothered about the duration - seems to be slightly easier to reach than the EML2 for its minimum energy orbit and slightlier easier to reach than the Moon for the minimal duration orbit. See delta v table

That was hard for me to get my head around. I was thinking how can it stay in the same region of the sky? It makes a complete circuit about the earth every year. Then it occurred to me as it moves 360 wrt earth, the earth moves 360 wrt sun.

Offline MP99

As to visiting it, a lunar encounter with a phased entry into the same gravitational equipotential would be the obvious choice, like entering a Lissajous orbit. If your US were long lived enough for a post lunar burn you could save much time (down to a few months), but if we're being economical, a hundred kilogram SEP craft that shared a GTO-1800 ride as a secondary might make it in a few years or less, depending on launch and if you could coax a third burn post primary payload, and the moon's position. Such a mission would take longer to design/fund/build/launch then to fly ;)

Many thanks for that info.


The fact that the solar wind doesn't perturb it much (hundreds of years stability) suggests a high density.

I had assumed that the hundreds of years was based on projecting back from current orbit.

If it is low enough density to be perturbed, then that just seems to invalidate the assumption, IE it could be a man-made object that seems to be long term stable due to a fluke of current position.

Online Comga

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Even more strange claim. I strongly doubt anyone has been able to measure the mass of this object.
Of course they have.
http://www.scientificamerican.com/article/how-do-scientists-measure/

 - Ed Kyle

The OP was asking about THIS object, and since we haven't had a spacecraft near it, there's nothing for it to perturb gravitationally to get a mass.  What you'd do is figure a few 1000 kg/m^3 density, give a factor of 2 uncertainty (mostly on the low side in case it's like Mathilde).  Given the uncertainty in the size, there's probably about a factor of 10 uncertainty in mass right now.  I suspect the size can be measured pretty accurately by radar from the intensity of a reflected signal.

Given that Congress seems to want to kill ARRM, it would probably be more useful to think of a low-cost way to get a probe to the asteroid.  The Japanese Procyon would likely be a good departure point for a design, but of course its SEP failure would have to be diagnosed and remedied.
If the orbit is known, the mass is known.

 - Ed Kyle

[Jim]
Wrong
[/Jim]

That statement is incorrect.  Knowing the current orbit says nothing about the mass.

edit: If orbits depended on mass, people could not occupy the ISS, as they have 1E-4 the mass of the station but co-orbit with it nicely, as do even small objects.

Tracking the orbit over years or decades can give an indication of mass due to forces other than gravity, like the Yarkovsky effect or YORP, but there doesn't appear to be enough data on 2016 H03, as the first images on PANSTARS is from 2012, four years ago.

Again, the Arkansas Sky Observatories website makes a specific statement about 2016 HO3 having a mass lower than one would expect for the brightness.  It is not clear how they can make this statement.  I have yet to find any paper or release with an independent measure of mass or density.

edit 2: Can you tell us how to determine the mass, Ed?
« Last Edit: 06/21/2016 08:12 PM by Comga »
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Online Space Ghost 1962

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The fact that the solar wind doesn't perturb it much (hundreds of years stability) suggests a high density.

I had assumed that the hundreds of years was based on projecting back from current orbit.

If it is low enough density to be perturbed, then that just seems to invalidate the assumption, IE it could be a man-made object that seems to be long term stable due to a fluke of current position.

There are many ways to handle retrospective analysis. One that comes to mind at UCLA used known observations to allow them to discover integration errors in sub arc second consistency, which for million year integrations could be checked with other means in the gross sense. Some have done likewise.

Of course, we could assume gross mathematical negligence like some, but for it to be so stable as suggested beggars the imagination too ... when your codes are wrong, they never converge.

Another way to do this is to model the cyclical variations, such that you know the impulse of known transient effects, and correlate that with the astable orbit, to determine "how long" it could survive. In that case, you are making a judgement based on the means by which the orbit is stable, not by retrospectives.

Keep in mind that it is not a "gravitation-ally bound" object. Not suspended in a Lagrange point. Not working strictly as a Keplerian object.

Also note the sizable variations in its orbit - a fair fraction of Earth-Moon distance.

Injecting an object to an orbit like this will take a lot of skill. In terms of random odds for insertion, likely in the billions if not more.

Why its likely "dense" and not man made "fluffy" is that those variations you see have exponentials tied to them, won't take much to escape into helocentric ejection - its already at/above escape velocity.

So what is retaining it is likely higher order terms of a N > 4 body problem. Where an equipotential "well" exists that is deep enough for such a mass.

With the S-IVB stage we know of (J002E3), it ejects to heliocentric and gets recaptured. Some think that this is affected by solar effects.

Again, because it is close enough that inverse square law losses for the bounce to be "brute forced", one can discern this by comparison. By all means one must decide this first. There are only so many SIVB, and the only way one could enter this orbit I can find for such would involve three significant burns post Moon, the first 4+ days after the vehicle expended ...

add:

From:
NASA NEAR EARTH OBJECT PROGRAM NHATS Object/Trajectory Details
Quote
25 - 113 meters:
Estimated diameter in meters showing the minimum and maximum likely size based on assumed maximum and minimum albedos of 0.60 and 0.03, respectively. If the size is "known", a single value is shown instead. If a single value is shown, it should still be considered an estimate.
      
Note if it is a high albedo vehicle, the size will be much smaller.
[
« Last Edit: 06/21/2016 11:02 PM by Space Ghost 1962 »

Offline jongoff

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Perhaps this could be suitable for a BEO cubesat mission.

Duration should be reasonably short, distance for communicating back is fairly low. No issue with distance from the Sun for solar panels. Flyby would give useful info, and might not have to be at huge speed (depending on SC lifetime).

Cheers, Martin

A big problem is propulsion
It is safe to assume that the delta-V in the NHATS models is equally distributed among the three.
That means the flyby needs ~2.5 km/sec.
That's a lot of propulsion
Cubesats rarely have any, and none have had 1% of this.  And you know the tyranny of the rocket equation.
And no cubesats have had high Isp SEP.

We're working on a cubesat heliogyro solar sail under a NASA SBIR contract we just started. Still just in Phase I, so a long way to go, but it might be a way to do a mission like this...

~Jon

Offline Robotbeat

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A cubesat definitely /could/ have high-Isp propulsion. Just because none have so far doesn't mean they couldn't.
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Online Comga

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A cubesat definitely /could/ have high-Isp propulsion. Just because none have so far doesn't mean they couldn't.
Correct
A_M_Swallow reminded us of Busek's program to build high Isp engines for smallsats and cubesats.
Quote
Technology Development Project Selections announced on September 4, 2013. These should be available soon and in need of a mission (unless they were cancelled).
http://www.nasa.gov/content/technology-development-project-selections/#.V2YKmDVaHIV
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline jongoff

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A cubesat definitely /could/ have high-Isp propulsion. Just because none have so far doesn't mean they couldn't.
Correct
A_M_Swallow reminded us of Busek's program to build high Isp engines for smallsats and cubesats.
Quote
Technology Development Project Selections announced on September 4, 2013. These should be available soon and in need of a mission (unless they were cancelled).
http://www.nasa.gov/content/technology-development-project-selections/#.V2YKmDVaHIV

The challenge with high Isp cubesat propulsion is that cubesats tend to be very power limited, which means they probably optimize out to a lower Isp than a bigger satellite would (and they already typically optimize out to far lower Isp than ion engines are capable of).

~Jon

Online Comga

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A cubesat definitely /could/ have high-Isp propulsion. Just because none have so far doesn't mean they couldn't.
Correct
A_M_Swallow reminded us of Busek's program to build high Isp engines for smallsats and cubesats.
Quote
Technology Development Project Selections announced on September 4, 2013. These should be available soon and in need of a mission (unless they were cancelled).
http://www.nasa.gov/content/technology-development-project-selections/#.V2YKmDVaHIV

The challenge with high Isp cubesat propulsion is that cubesats tend to be very power limited, which means they probably optimize out to a lower Isp than a bigger satellite would (and they already typically optimize out to far lower Isp than ion engines are capable of).

~Jon

Correct.  Isp goes up with increasing power. From the Busek presentation going from 60W to 360W raises the Isp by 10%, from 3500 sec to 3850 sec., but several of the former engines may be enough. So the optimum would tend more towards a smallsat than a cubesat, with significant solar panels and redundancy for a year in interplanetary space, but not necessarily something on the scale of Dawn of Deep Space 1.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline KelvinZero

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The challenge with high Isp cubesat propulsion is that cubesats tend to be very power limited, which means they probably optimize out to a lower Isp than a bigger satellite would (and they already typically optimize out to far lower Isp than ion engines are capable of).
By power limited do you mean power/mass? I would have thought there was a scaling problem in the other direction for solar power/mass. (im not claiming any experience, just laymans logic)

Online A_M_Swallow

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The challenge with high Isp cubesat propulsion is that cubesats tend to be very power limited, which means they probably optimize out to a lower Isp than a bigger satellite would (and they already typically optimize out to far lower Isp than ion engines are capable of).
By power limited do you mean power/mass? I would have thought there was a scaling problem in the other direction for solar power/mass. (im not claiming any experience, just laymans logic)

He means straight forward power limited. Cubesats have small solar panels so it unlikely to have more than 50-100 watts of power. About the same as the lamp in my lounge used to use.

Offline Danderman

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Forgetting efforts to design a CubeSAT mission here, what about a more traditional survey, what are the requirements for a Discovery class mission to this object?

Offline KelvinZero

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He means straight forward power limited. Cubesats have small solar panels so it unlikely to have more than 50-100 watts of power. About the same as the lamp in my lounge used to use.
So is the problem that a thruster of half the power shoots out particles at less speed, rather than just half as many? Is this where the scaling problem is?

Comega said something directly above that could be interpreted that way, (edit, and on re-reading my other interpretations don't make sense).. so the problem is that it is hard making smaller thrusters efficient if you try to keep similar ISP?.. I guess like it is hard building a pistol to shoot bullets as fast as a rifle? There are totally different approaches* but I guess then you are starting from scratch?

*Come to think of it, such as light sails, but there are other electronic ones I have seen mentioned.
« Last Edit: 06/25/2016 01:19 AM by KelvinZero »

Online Comga

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I have a message from a gracious gentleman at the Arkansas Sky Observatories who says that the idea that 2016 H03 has low density has been disavowed. My guess is that it was not based on good evidence.
(Perhaps like why Percival Lowell had Clyde Tombaugh search that part of the sky. There were mathematical errors that suggested a large mass there. Instead of a giant, Tombaugh found a dwarf planet by luck. Fortuneately he found Pluto before the errors were corrected!)

Edit: So we have no evidence that 2016 H03 is anything but a natural asteroid trapped in an orbit such that any year we could launch a less-than-one_year round trip to it with practical velocities.
« Last Edit: 06/25/2016 04:33 AM by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Ludus

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If 2016 HO3 is in fact a natural 40-100m asteroid (likely) and if it also proves to be type with valuable resources either metallic or carbon (based on an exploration mission), how practical would it be to move it to a more useful location to be exploited? What would be required? Where would you move it?
« Last Edit: 07/01/2016 10:29 PM by Ludus »

Offline Solman

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If 2016 HO3 is in fact a natural 40-100m asteroid (likely) and if it also proves to be type with valuable resources either metallic or carbon (based on an exploration mission), how practical would it be to move it to a more useful location to be exploited? What would be required? Where would you move it?
One possibility might be to use the "mirror bees" or "laser bees" concept. Thrust is generated by.vehicles using lasers or concentrated sunlight to heat regolith while orbiting or in the proximity of the asteroid. Mining vehicles might be designed around a solar concentrator for PV power and use it to act as a "mirror bee" to alter the asteroid,s orbit while waiting for the launch window for Earth return. Alternatively, a solar powered laser might provide power and propulsion for a mining vehicle and the laser used during the wait.

Offline Ludus

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http://kunder.hey-ho.no/zaptec/media/zaptec_plasma_drilling.pdf

I'd think some version of this sort of plasma drill with a mass driver could do it with a pretty big either solar or nuclear power source.

Offline Hop_David

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If 2016 HO3 is in fact a natural 40-100m asteroid (likely) and if it also proves to be type with valuable resources either metallic or carbon (based on an exploration mission), how practical would it be to move it to a more useful location to be exploited? What would be required? Where would you move it?

For some asteroids that normally pass close to earth moon neighborhood, a small nudge can bring the asteroid close to the moon. A lunar fly by can cut velocity relative to earth. This wouldn't be an option for 2016 HO3, it doesn't come close to the earth.

Moreover, it's inclination is 8 degrees.

There are asteroids such as 2008 HU4 that could be parked in high lunar orbit for just a small amount of delta V. Sadly HO3 isn't one of them.

I talk about catching an asteroid here.

Online A_M_Swallow

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Can we send a reconnaissance satellite to HO3 for less that say $50 million?
A second satellite may be needed to relay the radio signals.

Offline Danderman

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You would think that some at NASA would be jumping at the chance to send a Pioneer class probe to H03 ASAP, since that would be a great target for the Asteroid mission.

Offline Hop_David

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You would think that some at NASA would be jumping at the chance to send a Pioneer class probe to H03 ASAP, since that would be a great target for the Asteroid mission.

It's not a great target for the Asteroid redirect mission. See my post above.

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From http://fluidandreason.com/constantq/, looks like someone crunching real numbers is convinced 2016 HO3 is viable for targeting with a large cubesat with high ISP.  (This contest would release it from the spent upper stage of SLS EM-1 mission after TLI.)

Quote
The ConstantQ™ thrusters will be used on the CubeQuest competition’s Miles spacecraft. This craft features 12 thrusters with a custom tank design, taking the craft to lunar orbit and to asteroid 2016 HO3.
....
The ConstantQ™ is a hybrid electrostatic thruster, featuring an exceptionally compact and power-efficient design with a self-neutralizing plasma flow. The thruster gives 1.25 mN of thrust (modes up to 2.4mN available), 760 sec Isp (modes over 3,500 sec available), at 5.5 Watts total input power (3W beam power) when tested in Argon. Our “Model H” system includes 4 thruster heads, high voltage electronics, and 1kg of solid Iodine in a 1.5kg total, 0.5U, 22W package, giving a 8kg 6U satellite 995 m/s delta-v. The Model H’s thrusters are canted allowing for both primary propulsion and attitude control without use of moving parts – an important factor in mission assurance.


Offline Zed_Noir

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You would think that some at NASA would be jumping at the chance to send a Pioneer class probe to H03 ASAP, since that would be a great target for the Asteroid mission.

It's not a great target for the Asteroid redirect mission. See my post above.

Think @Danderman isn't thinking of the Asteroid redirect mission. Seems a small stream of mini spacecrafts with duo cameras & SEP should be enough for flyby look.

Offline bad_astra

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Why not Dragon asteroid 2017 as a Mars mission precursor!?
because people who become Mars obsessed aren't into rocks
"Contact Light" -Buzz Aldrin

Offline Robotbeat

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Why not Dragon asteroid 2017 as a Mars mission precursor!?
because people who become Mars obsessed aren't into rocks
Also, since the goal is Mars and the primary difficulty there (the problem which must be solved no matter the other details, and which must be solved to start major even robotic preparations) is EDL, why spend the money on a launch to a rock that isn't testing EDL?

If it's deep space operational experience and high speed reentry you want to test, a loop around the Moon would work, too, and would be faster.
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Offline the_other_Doug

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Why not Dragon asteroid 2017 as a Mars mission precursor!?
because people who become Mars obsessed aren't into rocks
Also, since the goal is Mars and the primary difficulty there (the problem which must be solved no matter the other details, and which must be solved to start major even robotic preparations) is EDL, why spend the money on a launch to a rock that isn't testing EDL?

If it's deep space operational experience and high speed reentry you want to test, a loop around the Moon would work, too, and would be faster.

And heck, if you're also testing landing ability, loop one around the Moon and land another one on it.

It's sort of reminiscent of Charles Lindbergh having Ryan Aircraft in San Diego build him a long-duration airplane capable of flying the Atlantic.  Getting it to New York for its departure could have been done one of two ways -- take the wing off, put it all on a couple of train cars, and ship it to New York via rail, or just fly it there.

Just flying non-stop from San Diego to St. Louis set a world's record for non-stop flight, and that was just the warm-up.

Doing a couple of quick shots to the Moon, to test out a few systems, isn't a bad idea.  Rather like setting a new world's record just getting your aircraft to the starting line.

But depending on delta-V budgets, I will also say that visiting a NEO as your equivalent of getting the spacecraft to the starting line might be more impressive to potential partners, who might see the Moon as been-there, done-that.  I bet the Moon would garner more public interest, though...
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Offline Robotbeat

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Except SpaceX isn't setting records by landing Dragon on the Moon, and it doesn't test out the kind of conditions they want. For the same amount of money, they could do another Mars landing attempt.

Which is what I think they'll do.
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Offline bad_astra

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There's a good reason for anyone wanting to colonize mars to take an interest in asteroids first, namely Phobos. You couldn't ask for a better way-station for Mars, for more reasons than I will go into here. Phobos makes doing Mars easier. And if you want to size up opreations on Phobos while getting to know it better why not pick the easiest NEO you can find as a test.

"Contact Light" -Buzz Aldrin

Offline RonM

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There's a good reason for anyone wanting to colonize mars to take an interest in asteroids first, namely Phobos. You couldn't ask for a better way-station for Mars, for more reasons than I will go into here. Phobos makes doing Mars easier. And if you want to size up opreations on Phobos while getting to know it better why not pick the easiest NEO you can find as a test.

Looks like BFS will do a direct EDL on Mars. Since BFS isn't stopping in Mars orbit before landing, Phobos can wait.

A mission to 2016 HO3 is a good idea, but it doesn't fit with what we know of SpaceX plans.

Offline Bynaus

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There must be some variant of Godwin's law in force around here requiring that in each thread, sooner or later, we will end up discussing the SpaceX Mars plans... :)

Seriously though: When looking for updates on the object (which is now officially called (469219) 2016 HO3) from the last few months, I found this study (seems to be a conference abstract):

http://www.aiaahouston.org/Horizons/Earth'sPseudo-MoonR0.pdf

So: minimum dv = 6.3 km/s (mainly because of the significant inclination) and a round-trip time of about a year. Not a very accessible object then, 2000 SG344 is much better in that respect.

Article in MNRAS (paywalled): https://mnras.oxfordjournals.org/content/462/4/3441

And look here for new citations of the article in the scientific literature: https://mnras.oxfordjournals.org/cgi/crossref-forward-links/462/4/3441
« Last Edit: 09/07/2016 08:10 PM by Bynaus »

Offline Ludus

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« Last Edit: 11/11/2017 02:36 PM by Ludus »

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