First Moon Picture from Japanese Orbiter

I am not going to touch on the pictures since they are not the item that i'm interesting in talking about. I'm more interested in the small bits of data that Zorgon listed under each pic.

First pic was taken around 2:50 @ 1500km.

Second pic was taken around 3:00 @ 1200 km.

Third pic was taken around 3:10 @ 800 km.

So in the short amount of time between pics you are going to tell me that this orbiter was able to reduce its altitude 186 miles in 10 minutes then drop another 248 miles of altitude in the next 10 minutes?

This sounds like it is on a crash course into the surface but i'm not a controller so I hope someone can help me out here. What would happen if the gravity of the Moon isn't what Japan thinks it is? They said it has orbit correction maneuver time and it is currently in that stage since it just released the relay satellite.

Is this normal for orbiters to reduce altitude that fast? Why did it drop more altitude during the second ten minutes? Shouldn't it drop more altitude at earlier times then gradually slow down as it approaches it's required orbit altitude?

Is there any more altitude change data available?

I read that it will operate from 100km circular orbit. With the info I just talked about it should already be in its operational orbit and ready to start its mission if it can drop 700 km in 20 minutes? It only needed another 700km to get into the 100km range it requires. Once again, I need help from someone who has put objects in orbit or know something we can reference this to.

According to the Jaxa site they said they are still moving closer to the 100km orbit. Why is it taking so long? Why is it going to take a week after VRAD seperation to get this into the 100km orbit? Why will it take a few more weeks to check out all the systems before it starts its mission?
www.selene.jaxa.jp...

I think this satellite is further along then we are being told. I really hope someone can help me understand why it takes 20 minutes to drop from 1500km to 800km then ten days to drop from 800km to 100km. I can understand taking it slow, but this seems fishy to me.

reply to post by jra


Good job Jra. I looked over the map you provided and the JAXA image and everything appears spot on.

reply to post by jra


Actually you are absolutely right the camera that took those images was an onboard monitering camera for the high gain antenna.

However have you seen Mike Deagans photo mosaic of the moon ?, that was taken using a Toucam pro II, a webcam, I think with the cost of larger cmos image devices dropping a lot of low end cameras can give impressive results.

reply to post by NJ Mooch


Well I am a little fuzzy on this too but I think Kaguya was in an elliptical orbit at the time and moving towrds the Moon I am basing my thinking on this schematic.






www.selene.jaxa.jp...

Originally posted by ArMaP
What is high resolution is the TV camera, and anyone can compare that kind of image with these images of the Moon by looking at the first image that was released, this image.

OMG that's so fake! Looks like CGI. I can't get that photo to line up with my map of Earth (one that NASA made) so they're not fooling me. Wait what's that in the corner? I think I see Gamera!!!!

Originally posted by sherpa
Well I am a little fuzzy on this too but I think Kaguya was in an elliptical orbit at the time and moving towrds the Moon I am basing my thinking on this schematic.

You are correct, it is in an elliptical orbit and it's slowly changing it into a circular one. Oct 19th is when it should be in its final orbit.

Originally posted by sherpa
However have you seen Mike Deagans photo mosaic of the moon ?, that was taken using a Toucam pro II, a webcam, I think with the cost of larger cmos image devices dropping a lot of low end cameras can give impressive results.

I don't think I've seen Mike Deagans mosaic, but I know a number of amature astronomers use webcams and the like for taking images, but from what I know, they do it by recording a video and then stack a few hundred frames to get a sharper, clearer image. It seems to be a pretty good method.

Originally posted by sherpa
Or maybe just check they are not going to get any surprises by doing a few orbits before going public.

Yes In fact they may want to make SURE no one else is there...

Maybe they took Buzz Aldrin seriously when he said people on the Moon will speak Chinese

Those two never did get along... so maybe they are just checking... And here I though maybe they might be speaking German... but I guess Buzz would know better...

one.revver.com...

Originally posted by jra
You're making way to big a deal out of it.

Perhaps... as I said I will wait for the 'good stuff' but in the meantime...

Originally posted by NJ Mooch

First pic was taken around 2:50 @ 1500km.

Second pic was taken around 3:00 @ 1200 km.

Third pic was taken around 3:10 @ 800 km.

So in the short amount of time between pics you are going to tell me that this orbiter was able to reduce its altitude 186 miles in 10 minutes then drop another 248 miles of altitude in the next 10 minutes?


Is this normal for orbiters to reduce altitude that fast? Why did it drop more altitude during the second ten minutes? Shouldn't it drop more altitude at earlier times then gradually slow down as it approaches it's required orbit altitude?

Thanks for the post NJMooch. The reason that all camera satellites assume elliptical orbits (such as Lunar Orbiter, Luna, Zond and others) is because the moons gravity is 64% that of earths.

To maintain a circular orbit in 64% of earths gravity you would have to orbit around 60 to 70 miles as did the Apollo spacecraft.

However, to get closeup photos you have to assume an elliptical orbit so that the speed of the flyby will not let your spacecraft crash into the moon.

If the moon really had one sixth gravity of earth you would be able to maintain a circular orbit at 15 or 20 miles above the surface of the moon depending on the weight of your spacecraft.

Lets dispense with this one sixth gravity. Its nonsense and always has been.

Originally posted by johnlear
If the moon really had one sixth gravity of earth you would be able to maintain a circular orbit at 15 or 20 miles above the surface of the moon depending on the weight of your spacecraft.

What formula did you use to come up with that figure?

Also, who signed off on your airman certificates?

Thanks.

Originally posted by Access Denied

What formula did you use to come up with that figure?

Bullialdus/Newton law of inverse square for the 64%, ballparked the 15 to 20 miles. Is there a problem?

Also, who signed off on your airman certificates?

Thanks.

Each certificate and each rating required a different signature. There were over a hundred. These don't include any recurrent checks. Which one were you interested in? I have a complete set of records.

Yes John, could you clarify your orbital math for us?

Originally posted by johnlear
Is there a problem?

Yes. You apparently have no idea what you're talking about.

Originally posted by johnlear
Each certificate and each rating required a different signature. There were over a hundred. These don't include any recurrent checks. Which one were you interested in? I have a complete set of records.

All of them. So are you saying none of them were recurrently checked or did I misunderstand you?

[sorry to the OP for the OT]

Originally posted by Access Denied

So are you saying none of them were recurrently checked or did I misunderstand you?

Each certificate and rating must have a recurrent check. Sometimes every 6 months sometimes every year. I took several hundred recurrent checks over 40 years. Each of those recurrent checks are by a different inspector. So when you say, "who signed you off' we are talking about hundreds of different FAA inspectors. Which one were you interested in?

Originally posted by IgnoreTheFacts

Yes John, could you clarify your orbital math for us?

Thanks for the post ITF. Beginning from where? The moon having 64% of earths gravity or the 15 to 20 miles circular orbit?

Thanks again for the post.

Originally posted by johnlear
Beginning from where? The moon having 64% of earths gravity or the 15 to 20 miles circular orbit?

Do both please.

Also did you look at my relabeled map? Does it look better to you?

[edit on 14-10-2007 by jra]

Originally posted by johnlear
Which one were you interested in?

Like I said, all of them.

(specifically who signed off on each original airmen certificate i.e. whether or not you took all the tests administered by a FAA inspector or DPE or merely received an endorsement from a flight instructor)

Also, did you have an Instrument Rating to fly under IFR?

Sorry if these questions have been asked before.

Thanks.

[back on topic]

I'm also looking forward to your answer to ITF and JRA.

Originally posted by johnlear
Bullialdus/Newton law of inverse square for the 64%, ballparked the 15 to 20 miles. Is there a problem?

There is a very significant problem: You made a very trivial and stupid error when trying to calculate the moon's gravity! I have proven this in the past on ATS at least twice. You can repeat your non-sensical statement as often as you want, but this won't make it true!

And if anyone had need more proof that you have absolutely no clue about Newton's laws, you gave it with this statement:

If the moon really had one sixth gravity of earth you would be able to maintain a circular orbit at 15 or 20 miles above the surface of the moon depending on the weight of your spacecraft.

First, no matter what the gravity of the moon is, you can always maintain a circular orbit at ~15 miles above surface! Only your orbital speed depends on the gravity!
Second, this orbit is absolutely independent of the mass of the spacecraft (as long as it's significantly less than the mass of the moon itself)! That's why a ~100kg free-floating astronaut can maintain position near a ~100 ton space station - they're both in the same orbit!

What you tell about moon orbits and moon gravity is complete and utter nonsense! And don't give me any of your "It's only my opinion"-BS! Orbital mechanics are not a matter of opinion. Heck, even all your alleged "secret space stations" would have to rely on Newton's laws to work as we (i.e. everyone except you) know it !

Regards
yf

Originally posted by yfxxx
First, no matter what the gravity of the moon is, you can always maintain a circular orbit at ~15 miles above surface! Only your orbital speed depends on the gravity!

Poppycock and Boonswaggle!! And I thought you knew a thing or two about orbital mechanics...

Circular orbit around the Moon? Try that and your ship will be moon dust in a few days... Since the moon is NOT a sphere and has several major gravity anomalies you would need to maintain an eliptical orbit. NASA found this out the hard way...

I hope the Japanese are smarter

Nov. 6, 2006: Near the end of the mission of Apollo 16, on April 24, 1972, just before returning back home to Earth, the three astronauts released one last scientific experiment: a small "subsatellite" called PFS-2 to orbit the Moon about every 2 hours....

The low orbits of both subsatellites were to be similar ellipses, ranging from 55 to 76 miles (89 to 122 km) above the lunar surface.

Instead, something bizarre happened.

The orbit of PFS-2 rapidly changed shape and distance from the Moon. In 2-1/2 weeks the satellite was swooping to within a hair-raising 6 miles (10 km) of the lunar surface at closest approach. As the orbit kept changing, PFS-2 backed off again, until it seemed to be a safe 30 miles away. But not for long: inexorably, the subsatellite's orbit carried it back toward the Moon. And on May 29, 1972—only 35 days and 425 orbits after its release—PFS-2 crashed.

What happened? The Moon itself plunged the subsatellite to its death. That's the conclusion of Alex S. Konopliv, planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena. He and several colleagues have been analyzing the orbits of various Moon-orbiting satellites since PFS-2, notably the 1998–99 mission of Lunar Prospector.

"If the Moon were a uniform sphere, you could have an orbit that was perfect ellipse or circle," Konopliv explained.

Absent any periodic boosts from onboard rockets to correct the orbit, most satellites released into low lunar orbits (under about 60 miles or 100 km) will eventually crash into the Moon. PFS-2 released by Apollo 16 was simply a dramatic worst-case example. But even its longer-lived predecessor PFS-1 (released by Apollo 15) literally bit the dust in January 1973 after less than a year and a half.

So before ya call others out on their ignorance of facts, maybe a little homework to make sure YOU don't sound like a grade school physicist?

Oh but wait... that data is from NASA ... so they must be lying

Originally posted by zorgon

Originally posted by yfxxx
First, no matter what the gravity of the moon is, you can always maintain a circular orbit at ~15 miles above surface! Only your orbital speed depends on the gravity!

Poppycock and Boonswaggle!! And I thought you knew a thing or two about orbital mechanics...

I sure know a lot more about that than John Lear, who knows nothing about it! And it was his posting I attacked.

But it's no surprise that his "First Officer" has to try and come to the rescue!

Anyway ...

Circular orbit around the Moon? Try that and your ship will be moon dust in a few days... Since the moon is NOT a sphere and has several major gravity anomalies you would need to maintain an eliptical orbit. NASA found this out the hard way...

Oh ... my ... G*D!! Of course the moon is not a perfect sphere, and every completely free-falling orbit will eventually distort! And this is true for circular and elliptical orbits. I know this, and my remark about possible low-altitude orbits did in no way deny this - I said nothing about the long (or not-quite-so-long) term stability of the orbits.

That said, you didn't address any of my points about moon orbits, which still are:
1) Minimum orbital altitude around the moon is not affected by the moon's surface gravity. (Disclaimer: Stability of orbits depend on higher-order components of moon gravity potential, but not on the moon's average surface gravity)
2) Orbital mechanics are not affected by the mass of the spaceship. (Disclaimer: This is only true for spaceships, which are much lighter than the moon itself)

So before ya call others out on their ignorance of facts, maybe a little homework to make sure YOU don't sound like a grade school physicist?

And you should do your homework and address the core points of a posting, instead of trying to escape towards a side route! And by the way ... it's better anytime to sound like a high-school physicist than like a complete ignoramus in the field (as JL does).

Regards
yf