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Chinese Space Program (CNSA) & Ch. commercial launch and discussion


tater

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  • 2 weeks later...
1 minute ago, JoeSchmuckatelli said:

What is an SSO (Sun Synchronous Orbit)?

So basically, the earth is not a perfect sphere, it's a bit squashed due to rotation, and bits of that spheres are more dense than others, meaning that the gravitational field is a bit lumpy. This means that spacecraft in orbit won't follow the orbit perfectly, it will change in subtle yet predictable ways over time.

A while back, some clever people found out that at a certain near polar inclination and altitude (or rather a range, it doesn't have to be exact AFAIK), these orbital perturbations would cause the orbit to rotate around in a circle (like spinning a coin, that axis) exactly once per year. If a spacecraft is launched into this orbit, along the day-night terminator, it will always be in sunlight, hence the name, sun synchronous orbit.

This is useful for a number of reasons. It allows for constant, predictable solar power, it covers all of earth except for maybe the very far north/south regions, and it allows for similar illumination/shadow conditions over all of earth, allowing for consistent imaging of the surface. As such, a lot of scientific earth observation satellites use this orbit.

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  • 5 weeks later...
8 minutes ago, YNM said:

Are those lightning in the background ?

Also, are the redder fires from like the gas-generators or something ?

I assume those pics were taken through filters, or else had some post-processing done, to bring out such gorgeous detail. The “lightning” IMO is the “silver lining” on clouds in the background. 

In pic 2 I don’t see any GG exhausts, but the Twitter comments opine that the orange flame is the smoke from the hypergolic flame. Highlighted by whatever photomagic was used for the shots. 

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3 minutes ago, StrandedonEarth said:

hypergolic flame.

Ah, yeah. Long March 3B does use hypergolics.

Also, nightshot, so yeah now I get how they did that. Probably a fairly fast shutter speed and certain launch trench placement.

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Can only be assumed given Xichang. Night launch, unlikely for people to spot the boosters falling down and stuff (unless for the slight explosion at the end maybe but hypergolics give more smoke than light AFAIK).

Also, new grain silo ?

 

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That makes China the 4th country to reach Mars, right?

US, CCCP, India, and now the PRC.

(note that I only include countries that build all the things themselves, all the ESA countries would be there had they launched on Ariane, for example, and buying all the things doesn't count at all (UAE), anymore than I can take credit for flying across the Pacific myself by purchasing an airline ticket).

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1 hour ago, tater said:

That makes China the 4th country to reach Mars, right?

If we count the failed orbital ejection / insertion as well, they're the 5th. Japan launched Nozomi on M-V rocket in July 1998, sadly it failed to enter Mars orbit (Earth departure failed after two lunar swing-by in December 1998, ends up having two Earth gravity assist in December 2002 and June 2003, intended Mars insertion in December 2003 failed completely and as such only resulting in 1000 km flyby).

Also had that mission been a success it'd have surpassed even Mangalyaan as the smallest probe to enter Mars orbit (258 kg dry + 228 kg propellant vs. 482 kg dry + ~550 kg propellant).

EDIT : Although if we count flybys then ESA would be the 5th with Rosetta (launched on Ariane 5 rather than Soyuz). But yeah if we count orbital insertions then it is the fourth.

EDIT 2 : The amateur mission followers and indications :

 

Edited by YNM
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27 minutes ago, YNM said:

If we count the failed orbital ejection / insertion as well, they're the 5th. Japan launched Nozomi on M-V rocket in July 1998, sadly it failed to enter Mars orbit (Earth departure failed after two lunar swing-by in December 1998, ends up having two Earth gravity assist in December 2002 and June 2003, intended Mars insertion in December 2003 failed completely and as such only resulting in 1000 km flyby).

I was thinking success to orbit, so yeah.

27 minutes ago, YNM said:

EDIT : Although if we count flybys then ESA would be the 5th with Rosetta (launched on Ariane 5 rather than Soyuz). But yeah if we count orbital insertions then it is the fourth.

Yeah, flybys would be another category.

Clearly ESA can get to other worlds (meaning they start with nothing, then go there, building a launch vehicle and spacecraft), as can Russia, the US, China, Japan, and India. In the not too distant future, NZ (Rocket Lab).

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10 minutes ago, tater said:

I was thinking success to orbit, so yeah.

Yeah I didn't notice the previous post was about successful insertion since it features the approach phase photo instead.

Also interesting how Mariner 9 arrived 13 days before Mars 2 while being launched 11 days after.

Edited by YNM
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14 hours ago, tater said:

buying all the things doesn't count at all (UAE), anymore than I can take credit for flying across the Pacific myself by purchasing an airline ticket).

So... does this mean Japan gets credit; they threw that rock

 

Edit: UAE may not have thrown their stone, but do they get any credit for running the insertion burn?

Edited by JoeSchmuckatelli
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