Astronomy and space exploration

[zed]

Watched TIANGONG-1 pass overhead about 1/2 hr ago 174km high, I also go it on video, it seemed to be about -4 magnitude, though only just your standard white satellite light (and not red like some ppl I seen mention on the internet)
Its coming overhead again in 34 mins, now at 158km high so perhaps I'll see it burning, fingers crossed

 

[zed]

https://arstechnica.com/science/2018/04/chinas-heavenly-palace-returns-to-earth-and-burns-up/
fuck just 2 or 3 more orbits (3-4 hours) & it would of been in a perfect spot, I missed it.
Seems to be in a similar spot to https://en.wikipedia.org/wiki/Deorbit_of_Mir
which I also remember in 2001 saturday night IIRC, I took a wine cask out to watch it come down over the pacific ocean (no smartphones then so had no tracking, just an idea sort of where and when to look) but it was a noshow, that was actually hyped up more than this which is wierd since everything nowadays is dialed up to 11 in the news
heres a still from the video I shot of Tiangong-1 last night

hopefully china goes to the moon and starts mining etc, just so it wakes the rest of the world up

 

[nutball]

SpaceX seem to be on a roll this month, so look out for the launch of TESS on the 16th!

 

[eloic]

Dwarf planet Ceres may store underground brine that still gushes up today
Waterlogged minerals and changing ice add to evidence that Ceres is geologically active

FOLLOW THE ICE A wall of ice in the shadows of Ceres’ Juling crater, shown here in an image taken by NASA’s Dawn spacecraft, grew by about 50 percent over the course of six months.​

https://www.sciencenews.org/article...e-underground-brine-still-gushes-today?tgt=nr

 

[eloic]

NASA Has a Plan to Put Robot Bees on Mars

https://www.space.com/40212-nasa-plans-robot-bees-on-mars.html

 

[rcf]

That'd be too easy! (Read: redneck... )
You actually don't need to climb anything or shoot yourself up to any altitude whatsoever to see the curvature of the Earth; just look up at the sky when you have a day with high-altitude cloud cover. You can see the clouds curving across the sky and meet the horizon some distance off; quite a ways, sure, but not nearly as far away as a flat Earth disc would be.

It's ironic that many (or most) "round earthers" themselves imagine the world just as they've seen it so many times on a rectangular 2D map that uses the Mercator projection, which means that they don't really know the correct size shape or position of continents and most countries.
Two interesting sites:
https://thetruesize.com
http://www.madmath.com/2017/04/mercator-projection-all-way-down.html

 

[eloic]

Elon Musk Shows Off 'Tool' for Mars-Colonizing Spaceship (Photo)

SpaceX founder and CEO Elon Musk posted this photo on Instagram on April 8, 2018. It shows "the main body tool" for the company's Mars-colonizing BFR spaceship, along with a Tesla car for scale.​

​

https://www.space.com/40243-spacex-mars-spaceship-elon-musk-photo.html

I'm so excited! I hope the first test flights can eventually take place next year.

 

[Grall]

Holy crab. And that's the shrunken-down version of the rocket... The really-REALLY Big F-...alcon Rocket was much larger-diameter still than that.

 

[eloic]

Holy crab. And that's the shrunken-down version of the rocket... The really-REALLY Big F-...alcon Rocket was much larger-diameter still than that.

Wait, what? Where did you get that info? I didn't know they will make a smaller version.

 

[eloic]

NASA Begins Building Next Mars Rover for 2020 Launch

NASA technicians have officially begun the assembly, test and launch operations (ATLO) phase of development on the agency's next Mars rover, keeping the project on track for an expected 2020 launch.​

https://www.space.com/40260-nasa-begins-building-mars-2020-rover.html

Well... I don't know if I should think that these Mars missions are getting a bit redundant. I still prefer that they invest in a bigger jump (a really big Mars mission) and in missions for other planets/moons (Venus, Jovian moons, etc.), instead of these "one little step at a time and oh, again in Mars".

 

[cheapchips]

Wait, what? Where did you get that info? I didn't know they will make a smaller version.

It was at Musk's IAC update in Sept. They've gone from 12m diameter to 9m. It makes it a much more affordable design. Still around 150t to orbit. It's a more versatile option. They can replace the Falcon 9 over time, utilising the resources they current plough into that.

The 12m was a little too big to be useful in LEO. For the foreseeable future anyway.

 

[Grall]

Also, the 12m dia rocket would have had an absolute shitload of rocket engines, just a crazy ludicrous number, far more than the failed Soviet moon rocket (whatsitscalled... N12?) as I recall.

The smaller diameter BFR still has a really huge number of engines.

 

[nutball]

N1.

Things have moved on though. Rocket science is still rocket science, but amongst other things materials technology, the fidelity of design simulation and the capability of real-time control systems has a changed beyond measure since the 60s. Private companies can now do things that once-upon-a-time nation states struggled to achieve.

If anything, the things that haven't changed are geography and politics. From my understanding of the decision to downsize from 12m to 9m, these were at least as important as the technological considerations.

 

[cheapchips]

The n1's not really an example of many engines=a bad day. There were all sorts of quality control issues with the project, as well as a test in flight mentality. They were out funded. The history of the thing is interesting.

On the 12m design, they'd have needed serious government funds to do it quickly. That's all tied up with the SLS jobs project, no one bit after the IAC 2016 presentation.

They'd also have needed to build a new launch site. Pad39a is just about able to cope with the thrust of the 9m version.

They had planned to build the 9m version at their hawthorn factory. It would have cost $2.5m to get it out of LA so are building an assembly facility on the port instead. The big layup tool above is in a giant tent just up the road from that site at present.

 

[Grall]

The n1's not really an example of many engines=a bad day.

Well, seeing as all N1:s ever launched asploded due to engine failure, it kind of was in the 1960s... A rocket engine has many parts which have to perform within spec to function properly, if your rocket has a couple dozen engines, well, that's a lot of points of failure - and if your engines aren't all that reliable in the first place, well, good luck...

Falcon Heavy seems to have proven it doesn't have to be that way today, sure, but still, more engines will mean more points of failure.

 

[cheapchips]

Well, seeing as all N1:s ever launched asploded due to engine failure, it kind of was in the 1960s...

Only two failures were engine failure I believe
The others were a tank issue and another with roll control?

The nk-33 has been a fantastic engine. It was just quality control issues with the N1. They only tested some out of each batch!


Contrast to F9/F9H engines which are tested individually, test fired together and test fired again at the launch site.

 

[nutball]

Falcon Heavy seems to have proven it doesn't have to be that way today, sure, but still, more engines will mean more points of failure.

Well it also means more redundancy. Modern sensing and control systems can go a long way to anticipating that an engine might be about to let go, then shutting it down in a controlled manner and increasing the throttle on the remaining engines to compensate. AFAIK none of that was possible in the era of the N1, so engines if did fail it was much more likely to be catastrophic.

 

[Grall]

While increased redundancy is positive, the drop in thrust can be an at least partial showstopper as happened when one of the early F9 missions blew an engine and was unable to complete its full mission due to lack of required delta-v IIRC. What exactly they had to drop eludes me at the moment though, some satellite they had to splash maybe?

Granted, by losing only 1 engine the F9 lost over 10% of its total thrust, the BFR losing one single engine would be only a few percent thrust, so could perhaps be compensated by throttling up the other engines. It'd put some extra wear on the rocket, but maybe not a biggie overall. *shrug*

 

[Grall]

Contrast to F9/F9H engines which are tested individually, test fired together and test fired again at the launch site.

Reminds me how Rolls-Royce grew the original WWII-era Merlin engine (27-ish liter/900something kilogram V12 supercharged monster used in the Supermarine Spitfire and others) from like 1200 horses up to nearly 3000 IIRC in the space of a few years. Allegedly, they took a random engine off the assembly line and strapped it to a testbench, then ran it full throttle until it blew up. Then they picked the pieces apart and found out what component failed and improved it.

Better quality fuel also helped.

 

[pcchen]

While increased redundancy is positive, the drop in thrust can be an at least partial showstopper as happened when one of the early F9 missions blew an engine and was unable to complete its full mission due to lack of required delta-v IIRC. What exactly they had to drop eludes me at the moment though, some satellite they had to splash maybe?

I think it's the first CRS (commercial resupply mission) launch. One of the F9 engine shut down during launch, and NASA did not allow a second re-ignition for a ISS bound mission, so the second payload (a small comm satellite) didn't go to the correct orbit and was lost.