What "weed need" is a space mission! - Page 82

Uncwilly · 2018-12-29, 09:30

Hopefully all of the news media cover New Horizons encounter with Ultima Thule (closest approach is right around the change from 2018 to 2019 in the Eastern time zone) as well as they did for Pluto.

Also, NROL 71 may actually shuffle of the surface on Saturday.

xilman · 2019-01-01, 17:42

Quote:

Originally Posted by Uncwilly

Hopefully all of the news media cover New Horizons encounter with Ultima Thule (closest approach is right around the change from 2018 to 2019 in the Eastern time zone) as well as they did for Pluto.

Also, NROL 71 may actually shuffle of the surface on Saturday.

It got there intact and has phoned home. If Ultima Thule has an atmosphere or a dust cloud it was too thin to cause damage.

Nice picture, BTW. resolution not quite good enough to distinguish between a contact binary or a co-orbiting pair.

Spherical Cow · 2019-01-01, 17:56

Quote:

Originally Posted by xilman

It got there intact and has phoned home. If Ultima Thule has an atmosphere or a dust cloud it was too thin to cause damage.

Nice picture, BTW. resolution not quite good enough to distinguish between a contact binary or a co-orbiting pair.

Outstanding- 6.5 billion km, and it skims past an object a few tens of km wide, and reports back using a 15 watt transmitter. Just incredible.

Uncwilly · 2019-01-01, 18:05

Quote:

Originally Posted by xilman

Nice picture, BTW. resolution not quite good enough to distinguish between a contact binary or a co-orbiting pair.

The images that they released were from significantly early. I took a single raw image and did some ham fisted processing to get this.

Brownfox · 2019-01-01, 20:12

Yop. Better images should be available tomorrow and then better still in the coming months. Current best guess seems to be a single elongated structure (think bowling pin) rather than a co-orbiting pair.

Dr Sardonicus · 2019-01-01, 20:50

Quote:

Originally Posted by Spherical Cow

Outstanding- 6.5 billion km, and it skims past an object a few tens of km wide, and reports back using a 15 watt transmitter. Just incredible.

Just how incredible? The following was when NH was flying by Pluto. The quoted passage is about the challenges at the receiving end. When the Voyager probes were flying by Saturn, a guy from JPL described one major problem as being that "the receiver is not at absolute zero."

How strong is the signal transmission system on New Horizons that it's able to send data back to earth 3 billion miles away?

Quote:

These dishes produce a signal about 29 million times stronger than the smallest possible antenna on that frequency band but it is still incredibly weak: about a millionth of a millionth of a millionth of a watt.

This is so weak that it would be completely lost in the receiver's own noise, so special amplifiers mounted right in the dish and cooled by liquid helium are used to boost the signal while adding as little noise as possible. Other sources of noise include water vapor in the atmosphere and even the distant cosmos behind the spacecraft, but little can be done about them.

Yet the signal is still so noisy that it would be lost if not for a final trick: error correction coding. New Horizons generates and adds 5 "parity" bits for each data bit so that when noise corrupts some of them they can be detected and corrected.

chalsall · 2019-01-02, 02:33

Quote:

Originally Posted by Dr Sardonicus

The quoted passage is about the challenges at the receiving end. When the Voyager probes were flying by Saturn, a guy from JPL described one major problem as being that "the receiver is not at absolute zero.

What most people don't appreciate is the receiver has much more difficulty than the transmitter in getting a message through.

Please see this Wikipedia article -- Shannon-Hartley theorem.

Interestingly, this forum has a much better Signal-to-Noise Ratio (SNR) than most of the entire Internet....

Uncwilly · 2019-01-02, 04:50

In the book about NH Alan Stern talked about how that the low bit rate was an intentional choice to make the mission possible. The power limitation of a single RTG was one factor. Size/mass/complexity of the antenna was another factor.

I grabbed the latest and best image and processed it again. Looks like the larger lobe has a lump on the side.

axn · 2019-01-02, 06:03

Quote:

Originally Posted by Uncwilly

I grabbed the latest and best image and processed it again. Looks like the larger lobe has a lump on the side.

Now it looks like a fetus. Pareidolia FTW!

Dr Sardonicus · 2019-01-02, 13:53

Quote:

Originally Posted by Uncwilly

I grabbed the latest and best image and processed it again. Looks like the larger lobe has a lump on the side.

Remember the "Dawn of Man" scene from 2001: A Space Odyssey? It's the bone!

xilman · 2019-01-02, 18:45

Quote:

Originally Posted by Dr Sardonicus

Remember the "Dawn of Man" scene from 2001: A Space Odyssey? It's the bone!

Nah, it can't be. It came back down and killed the pre-human. Remember Gilliam's Monty Python cartoon?

2019-01-02, 04:50	#899
Uncwilly 6809 > 6502 """"""""""""""""""" Aug 2003 101×103 Posts 2³·1,223 Posts	In the book about NH Alan Stern talked about how that the low bit rate was an intentional choice to make the mission possible. The power limitation of a single RTG was one factor. Size/mass/complexity of the antenna was another factor. I grabbed the latest and best image and processed it again. Looks like the larger lobe has a lump on the side. Attached Thumbnails

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2018-12-29, 09:30	#892
Uncwilly 6809 > 6502 """"""""""""""""""" Aug 2003 101×103 Posts 2³×1,223 Posts	Hopefully all of the news media cover New Horizons encounter with Ultima Thule (closest approach is right around the change from 2018 to 2019 in the Eastern time zone) as well as they did for Pluto. Also, NROL 71 may actually shuffle of the surface on Saturday.

2019-01-01, 20:12	#896
Brownfox Dec 2017 67 Posts	Yop. Better images should be available tomorrow and then better still in the coming months. Current best guess seems to be a single elongated structure (think bowling pin) rather than a co-orbiting pair.