Recent Posts

Pages: [1] 2 3 ... 10 Next
3
I can't help but to conclude people are just way too worked up about Ti fins.
SpaceX might be planning to use Ti fins only with Block V intended for reuse (there's still the possibility of a few expendable Block V launches).
Maybe Block V and FH launches.
There is no evidence that Al fins have to be refurbed after a LEO mission, which is the only scenario for reuse so far (booster used on a single LEO launch).
Its possible the same Al fins can fly a few times on LEO missions.
SpaceX knows their safety margins. Just because it glowed during re-entry, doesn't follow the fins are gone.
After all they have withstood a few recoveries which were hail marry attempts.

That single Ti fin launch likely was to verify its operations, and Al fins are good enough for current missions.

How about a little less obsessing, please ?

Obsessing is what we do, though... SpaceX is also obsessing about rapid turn-around after flight (if 24 hour goal isn't obsessive, not sure what is) and the Ti grid fins put that component to bed as far as rework is concerned*.

Obsessing aside, Block 5 will be manufactured for rapid reuse, end-to-end.  Expect nothing but a post-flight inspection if they are successful. 


* Probably including GTO flights.
4
I can't help but to conclude people are just way too worked up about Ti fins.
SpaceX might be planning to use Ti fins only with Block V intended for reuse (there's still the possibility of a few expendable Block V launches).
Maybe Block V and FH launches.
There is no evidence that Al fins have to be refurbed after a LEO mission, which is the only scenario for reuse so far (booster used on a single LEO launch).
Its possible the same Al fins can fly a few times on LEO missions.
SpaceX knows their safety margins. Just because it glowed during re-entry, doesn't follow the fins are gone.
After all they have withstood a few recoveries which were hail marry attempts.

That single Ti fin launch likely was to verify its operations, and Al fins are good enough for current missions.

How about a little less obsessing, please ?

I mostly agree, but if an aluminium fin starts to glow, it's had it, since at the point of glowing it's lost all strength.

As several folks have pointed out, the glow we see in the entry footage is indicative of not necessarily "glowing white hot" aluminum. Rather, removal of a camera's IR filter combined with over-saturation of the camera sensor in the near-IR bands. Yes, the fins get hot. But not - generally speaking - hot enough to glow white to a human eye, as the camera footage appears to show.

Yes, some of the earliest landings showed fin webs eroded or even burned through in one or two cases. But it's clear SpaceX has either changed coating substances or application techniques, perhaps combined with entry trajectory shaping, since we've not seen any such obvious fin damage on recently-returned cores.
5
I can't help but to conclude people are just way too worked up about Ti fins.
SpaceX might be planning to use Ti fins only with Block V intended for reuse (there's still the possibility of a few expendable Block V launches).
Maybe Block V and FH launches.
There is no evidence that Al fins have to be refurbed after a LEO mission, which is the only scenario for reuse so far (booster used on a single LEO launch).
Its possible the same Al fins can fly a few times on LEO missions.
SpaceX knows their safety margins. Just because it glowed during re-entry, doesn't follow the fins are gone.
After all they have withstood a few recoveries which were hail marry attempts.

That single Ti fin launch likely was to verify its operations, and Al fins are good enough for current missions.

How about a little less obsessing, please ?

I mostly agree, but if an aluminium fin starts to glow, it's had it, since at the point of glowing it's lost all strength.
6
There's something that has always bugged me about this being an alien ship: why would they prefer a long shape over any other for a non-atmospheric ship? Ok, I get the O'Neill cylinder concept, but there are countless others with many morphologies... these "elongated shape = spaceship" are too (childishly, IMO) influenced by popular science fiction, and lack imagination -- when their proponents make it seem as if they are the one entertaining imaginative out-of-the-box ideas.

Well, it makes sense for a fast interstellar ship to expose only a small cross-section towards the direction of flight. I guess the best shape would be an elongated ellipsoid with an axis ratio proportional to the relativistic dilatation factor it can reach (so that the ship is an effective sphere at cruising speed). A 10:1 ratio would then correspond to a top velocity of 99.5% c. :)
7
SpaceX General Section / Re: SpaceX - now a satellite manufacturer?
« Last post by JamesH65 on Today at 12:19 PM »
Throw in the they follow Net Neutrality (if they choose) then I would sign up.

Right, it would be nice if SpaceX could make a statement about net neutrality.

They haven't really made many statements about the satellite system at all, asking them for statements about NN would be somewhat premature.
8
I can't help but to conclude people are just way too worked up about Ti fins.
SpaceX might be planning to use Ti fins only with Block V intended for reuse (there's still the possibility of a few expendable Block V launches).
Maybe Block V and FH launches.
There is no evidence that Al fins have to be refurbed after a LEO mission, which is the only scenario for reuse so far (booster used on a single LEO launch).
Its possible the same Al fins can fly a few times on LEO missions.
SpaceX knows their safety margins. Just because it glowed during re-entry, doesn't follow the fins are gone.
After all they have withstood a few recoveries which were hail marry attempts.

That single Ti fin launch likely was to verify its operations, and Al fins are good enough for current missions.

How about a little less obsessing, please ?
9
Spaceflight Entertainment and Hobbies / Re: Star Trek Discovery
« Last post by Ronpur50 on Today at 12:08 PM »
Ok.  So Discovery is supposed to begin about 10 years before TOS ?
We know Burnham was on Shenzou for 7 years before the encounter with the Klingons.
While searching for the injured Sarek in the mind meld we find out that Spock turned down an offer to join the Vulcan Expeditionary Group in order to join Starfleet before Burnham left Vulcan.
While running laps around Disco's deck Burnham tells Tilly to try to get on a Constitution Class Starship like the Enterprise (presumably under the command of Christopher Pike).

So, what has Spock been doing for 17 years between leaving Vulcan and the start of TOS ?

Well, for 13 years, at least, he served on the Enterprise.  The events with Pike on Talos IV were said to have occurred 13 years before the events on The Menagerie.  So he must have been in Starfleet Academy or in Starfleet.
10
http://esa.int/Our_Activities/Space_Engineering_Technology/ESA_s_latest_technology_CubeSat_cleared_for_launch_site

ESA’S LATEST TECHNOLOGY CUBESAT CLEARED FOR LAUNCH SITE

23 November 2017

GomX-4B, ESA’s latest and largest technology-testing CubeSat, will be launched from China early next year, together with the near-identical GomX-4A. The pair will test intersatellite communication links and propulsion while orbiting up to 4500 km apart.

The cereal box-sized GomX-4B has been passed as ready to travel along with its twin from manufacturer GomSpace in Denmark in early December to begin launch preparations in China.

“GomX-4B is scheduled to be launched on a Chinese Long March rocket on 1 February, along with GomX-4A, owned by the Danish Ministry of Defence,” says Roger Walker, heading ESA’s Technology CubeSat initiative.

The majority of tests were made at GomSpace and other facilities in Denmark, apart from thermal–vacuum testing – ensuring that the CubeSats can withstand the hard vacuum and temperature extremes of low orbit – which took place at ESA’s technical centre in the Netherlands.

CubeSats are nanosatellites based on standardised 10x10 cm units. GomX-4B is a ‘6-unit’ CubeSat, double the size of its predecessor GomX-3, which was released from the International Space Station in 2015.

Roger adds, “The two CubeSats will test intersatellite link technology, routing data from one satellite to the other, then down to the ground station. Part of the ground testing ensured they could indeed talk to each other and the actual ground station on an end-to-end basis.”

Once released from the rocket, the CubeSats will first orient themselves to align their antennas. Then GomX-4B will gradually fly away from its counterpart, pausing at around 100 km intervals with their intersatellite links activated to see how well they work.


Their separation will be controlled by new cold-gas propulsion on GomX-4B contributed by Sweden’s NanoSpace company, using highly miniaturised thrusters.

They will maintain their links through flat, patch antennas and software-controlled radios at a maximum distance of some 4500 km – a limit being set by the operating concept of a minimum of 10 satellites equally spaced around the same orbital plane to form a future constellation.

“As well as operating together, the two also have separate payloads,” says Roger. “GomX-4B is the first CubeSat to fly our new HyperScout hyperspectral imager, developed by cosine Research in the Netherlands through ESA’s General Support Technology Programme.

“Hyperscout images Earth in 45 different spectral bands, gathering a wealth of environmental data – so much so, in fact, that the camera must perform its own processing to drastically reduce the amount needing to be sent back to the ground.”

GomX-4B also carries a new small startracker for precise attitude determination developed by Innovative Solutions in Space in the Netherlands, an ESA test payload checking components’ susceptibility to space radiation, and a dedicated radio receiver to detect signals from worldwide air traffic.

“Now the testing has been concluded, our main job is to keep the satellites’ batteries topped off, ahead of their transport to China,” concludes Roger. “Once they arrive, they will be checked and the propellant tanks filled.”

The pair is flying as secondary payloads with China’s Seismo-Electromagnetic Satellite, CSES-1, designed to detect precursor signals of earthquakes in Earth’s ionosphere, an electrically active outer layer of the atmosphere.
Pages: [1] 2 3 ... 10 Next