A new quasi-satellite was discovered in April: 2016 HO3

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OmCheeto
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This small asteroid is Earth's constant cosmic companion [JPL]
June 15, 2016

A small asteroid has been discovered in an orbit around the sun that keeps it as a constant companion of Earth, and it will remain so for centuries to come.

As it orbits the sun, this new asteroid, designated 2016 HO3, appears to circle around Earth as well. It is too distant to be considered a true satellite of our planet, but it is the best and most stable example to date of a near-Earth companion, or "quasi-satellite."
...
2016 HO3 was first spotted on April 27, 2016
From a spreadsheet I developed during the Ceres mission, I've calculated that the Hubble Space Telescope would barely be able to see it, with a resolution of only 0.026 pixels.
For comparison:
Object _____________Pixels
2016 HO3__________0.026
Pluto_______________2.1
Ceres______________18
Andromeda__284,000

It has a diameter of between 40 and 100 meters.
Maximum distance from Earth: 39 million km (100 times the distance to the moon)
Minimum distance from Earth: 14 million km (38 times the distance to the moon)

I used the minimum distance, and a diameter of 70 meters, for my Hubble resolution calculation.

 
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I've calculated that the Hubble Space Telescope would barely be able to see it, with a resolution of only 0.026 pixels.
Hubble sees it as point-like object, but it is bright enough to be easily visible, at ~1/10 the brightness of Pluto (order of magnitude).
 
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OmCheeto
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http://www.jpl.nasa.gov/news/news.php?release=2016-154
http://edition.cnn.com/2016/06/16/us/nasa-asteroid-circles-earth/
A small asteroid has been found circling Earth as the two objects orbit the sun together.
Scientists say it looks like the asteroid -- called 2016 HO3 -- has been out there for about 50 years and isn't going away anytime soon.
50 years ago gives 1966 so maybe it's another Saturn V S-IVB third stage like J002E3 from Apollo 12? It would be easy to test.

https://en.wikipedia.org/wiki/J002E3
J002E3 is the designation given to an object in space discovered on September 3, 2002 by amateur astronomer Bill Yeung. Initially thought to be an asteroid, it has since been tentatively identified as the S-IVB third stage of the Apollo 12 Saturn V rocket (designated S-IVB-507), based on spectrographic evidence consistent with the paint used on the rockets.[1][2] The stage was intended to be injected into a permanent heliocentric orbit in November 1969, but is now believed instead to have gone into an unstable high Earth orbit which left Earth's proximity in 1971 and again in June 2003, with an approximately 40-year cycle between heliocentric and geocentric orbit.
Maybe the modified stage 3 of AS-203, launched on July 5, 1966 wasn't inadvertently destroyed along with stage 2 after all. The modified stage 3 used would have to be very close to the weight of a normal stage 3 for the results to be useful.

https://en.wikipedia.org/wiki/AS-203
AS-203 (or SA-203) was an unmanned flight of the Saturn IB rocket on July 5, 1966. It carried no Apollo Command/Service Module spacecraft, as its purpose was to verify the design of the S-IVB rocket stage restart capability that would later be used in the Apollo program to boost astronauts from Earth orbit to a trajectory towards the Moon. It successfully achieved its objectives, but the stage was inadvertently destroyed after four orbits.
It could also be the third stage from Apollo 8, 9, 10 or 11 which are all recorded to have reached heliocentric orbit.

https://en.wikipedia.org/wiki/S-IVB#Stages_built
 
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OmCheeto
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http://www.jpl.nasa.gov/news/news.php?release=2016-154
http://edition.cnn.com/2016/06/16/us/nasa-asteroid-circles-earth/


50 years ago gives 1966 so maybe it's another Saturn V S-IVB third stage like J002E3 from Apollo 12? It would be easy to test.

https://en.wikipedia.org/wiki/J002E3


Maybe the modified stage 3 of AS-203, launched on July 5, 1966 wasn't inadvertently destroyed along with stage 2 after all. The modified stage 3 used would have to be very close to the weight of a normal stage 3 for the results to be useful.

https://en.wikipedia.org/wiki/AS-203


It could also be the third stage from Apollo 8, 9, 10 or 11 which are all recorded to have reached heliocentric orbit.

https://en.wikipedia.org/wiki/S-IVB#Stages_built
Very interesting. If I weren't so busy, I'd figure out if this feasible. And I'm not sure if I'd be able to find all the data necessary to figure it out. Perhaps my pen-pal at JPL might know. :oldsmile:
 
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They certainly studied that. They wouldn't announce it that way if there was a chance to be a rocket stage.
 
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tony873004
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Scientists say it looks like the asteroid -- called 2016 HO3 -- has been out there for about 50 years and isn't going away anytime soon.
"Our calculations indicate 2016 HO3 has been a stable quasi-satellite of Earth for almost a century..."
Probably a mistake from the author of the CNN article. One sentence after saying scientists say its been out there for about 50 years, they quote a scientist saying it been out there for nearly a century.

And by "a century" he means in a quasi-state for a century.
They found a precovery image dating back to 2004, so they are very confident with this asteroid's orbit. Rocket stages are heavily perturbed by non-gravitational forces due to their low density. So its much more difficult to predict its trajectory.
Also, its very unlikely that something would escape Earth and immediately enter a quasi state.
 
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They found a precovery image dating back to 2004, so they are very confident with this asteroid's orbit.
J002E3 was also thought to have ended up in a semi stable orbit around Earth and left Earth orbit in June 2003.

https://en.wikipedia.org/wiki/J002E3#Discovery
The most likely explanation appears to be the S-IVB third stage for Apollo 12.[1][2] NASA had originally planned to direct the S-IVB into a solar orbit, but an extra long burn of the ullage motors meant that venting the remaining propellant in the tank of the S-IVB did not give the rocket stage enough energy to escape the Earth–Moon system, and instead the stage ended up in a semi-stable orbit around the Earth after passing by the Moon on November 18, 1969.

It is thought that J002E3 left Earth orbit in June 2003, and that it may return to orbit the Earth in the mid-2040s.[1]
Rocket stages are heavily perturbed by non-gravitational forces due to their low density. So its much more difficult to predict its trajectory.
The stage 3 from AS-203 would actually have a mass, and subsequent density, of around 10 times more than a normal Saturn V S-IVB third stage with an expended fuel payload so it would be expected to behave differently and have a different trajectory. I assume NASA would have simulated the payload mass so they could get accurate and useful results from their tests.

http://history.nasa.gov/SP-4029/Apollo_18-19_Ground_Ignition_Weights.htm
 
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tony873004
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J002E3 was also thought to have ended up in a semi stable orbit around Earth and left Earth orbit in June 2003.
Yes, but it didn't enter a quasi-orbit such as the one 2016 HO3 is in. It simply entered an Earth-crossing solar orbit. Quasi orbits prevent close approaches to Earth. Getting captured into and out of Earth orbit makes it more like asteroid 2006 RH120. http://orbitsimulator.com/gravitySimulatorCloud/simulations/1433806156068_2006 RH120.html
This asteroid got captured into Earth orbit in 2006, made 3 orbits then escaped. But it was never in resonance with Earth.

The stage 3 from AS-203 would actually have a mass, and subsequent density, of around 10 times more than a normal Saturn V S-IVB third stage with an expended fuel payload so it would be expected to behave differently and have a different trajectory. I assume NASA would have simulated the payload mass so they could get accurate and useful results from their tests.
That's a good point. I thought we were talking about an empty tank. Thanks for the clarification.
 
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That's a good point. I thought we were talking about an empty tank. Thanks for the clarification.
Hi Tony, the stage should be empty.

I have just read the "RESULTS OF THE SECOND. SATURN IB LAUNCH VEHICLE TEST FLIGHT - AS-203 from NASA and must say I learnt alot and am very impressed with the massively great contribution the S-IVB guys made to the entire Apollo program, with the limited resources at their disposal.

After reading the NASA report and comparing the figures with the other Apollo missions it is apparent that the S-IVB stage used live fuel loads that were expended successfully before telemetry was lost so the AS-203 S-IVB stage would be a similar weight and density to J002E3. Comparing the S-IVB stage weight total and Instrument Unit weights for AS-203, Apollo 7, 8, 9, etc shows that the S-IVB stage weight change is due to the amount of LOX being carried as everything else is within a couple of % when payloads are excluded.

AS-203 was carrying 5/8 of the LOX of the typical Apollo mission so the Mass to LOX ratio would give a power to weight ratio equivalent to firing an Apollo program S-IVB stage with a small payload while leaving the stage in a heliocentric orbit like many of the others. Were the AS-203 S-IVB stage to have 100% of an Apollo missions LOX load it could effectively lift an Apollo equivalent moon bound payload.

There was enough LOX on AS-203 to launch a small payload onto an Apollo mission trajectory, the main engine run was complete and well accounted for, there was no record that it came down and the same weight specs apart from LOX were used as an Apollo program benchmark thereafter so I cannot really exclude 2016 HO3 from being something like AS-203 S-IVB stage 3.

Back in those cold war days it would probably be considered a good idea not to show all of your cards at once, just in case someone tried to peek. I can understand that. What I can't understand is why you wouldn't do a full restart and burn test if the opportunity came along and you were ready (command 'J2 Engine Start On').
 

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