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Missions To The Moon (HSF) / Re: NASA Gateway Lunar Lander
« Last post by jongoff on Today at 09:41 PM »
With a fuel depot infrastructure the single stage lander would not be too large for SLS or even a smaller vehicle like New Glenn or Falcon Heavy as it could act as it's own departure stage.

Yeah, it seems odd that they're talking about refueling and reuse of stages in lunar orbit but act as though you couldn't do the same thing in LEO--even if the rocket isn't a lander with legs on it.

~Jon
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Is this metric or imperial weeks? :)
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It's "Elon weeks"... ;)

Based on when he typed it, likely “4 weeks” was referring to after the DM-1 mission is complete. Now it’s about 5 weeks again.
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As stated above, NASA (not just DOD) wanted high cross range. This was considered vital for certain abort scenarios, whether those were used in practice or not. In particular I think some east coast abort scenarios required high cross range. Like an escape system it seems totally useless until you need it.
Because most of them were fantasy?
Being able to diagnose SSME partial failure modes, allowing an engine to continue running at partial thrust, probably improved the Shuttle survivability a great deal more than the theoretical benefits of untested (note that AFAIK none of the abort modes was tested in the flight test series before STS was declared "operational." Not exactly a cast iron guarantee of safety, or a vote of confidence in its architecture.

Quote from: joema
Oftentimes paper designs look feasible. The X-30 NASP initially looked like it could fly to orbit on airbreathing engines. It was only after much more rigorous modeling (which was not done for SERV) did it become apparent it wouldn't work.
Or because there was no due diligence done (as Heppenheimer's book points out) to identify that the design was started with the wrong thermodynamic properties for air (among other things).
Something that should have picked up before something north of $1Bn had been spent.
Quote from: joema
Quote from: john smith
...Remember the "Keep crew and cargo separate" meme is what produced Ares 1 and 5 and the CEV.  :(
In retrospect launching crew and cargo together is viewed as a shortcoming of the shuttle, but there was no other realistic option.
Correct.

Again it was the budget.  Given that between them NASA and OMB allocated enough for one new full engine and stage how would you build two vehicles (of very different size) out of that?
Quote from: joema
You can envision a different scenario where Saturn V production was maintained for years while an alternate space station was designed, then with only four launches it could lift four large sections with more mass than the current ISS. Then it might be serviced by a little shuttle. That is not an alternate design it is a totally alternate reality which had no chance of ever being approved.
Irrelevant. We know what actually happened.

This thread is about the notion of a future shuttle, not a parallel history where some other design of Shuttle got built.
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The abort occurred before any engines ignited, yes – and while LH2 wasn't flowing yet it would have been very soon. But some amount of LOX had been released for engine chilldown, so I'd wager MECO was called to verify all prop valves were fully closed.

What was the source of the fire then? The LOX gas burning the foam and other materials on the vehicle?
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I think that a breakthrough was finding due "parachute" landing, the fuel requirement for power landing is so low, that they could have little bit heavier ship.
They will not use some new unproven special material. they will use just staff that are using right now during falcon 9 build and Merlin rocket engine.
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I really love people who do nitpicking.

Yes, I did mean the first US (or western) spaceflight since the shuttle got retired.

But I have to admit - the gaps between Chinese flights are so long, that sometimes I forget about these.
You also forget that all those other "human spaceflight" things were orbital.

We can argue forever on the definition of "go to space", but bucketing all in the same bin is just wrong.

-----
ABCD: Always Be Counting Down

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As a consequence (but nobody seems to notice?) Farnes' model is an overunity theory.

EDIT: Comments from Sabine Hossenfelder about Farnes' theory. Hossenfelder is a physicist who published in Physical Review D a bimetric theory that also unifies dark matter and dark energy as one dark fluid, in 2008, ten years before Farnes (yet today ignored by memorylessness media). See also her 2009 presentation paper. She was the first to publish a Lagrangian derivation of a system of two coupled field equations managing positive and negative masses in cosmology with no runaway paradox, in a very similar way to the Janus cosmological model, which uses about the same sets of equations (except various additional "pull-overs" in Hossenfelder's theory).

I am by no means a proponent of the theory and would not want to die on this hill, but I thought this point was covered by Farnes in the paper here, which you partially quoted:

"One of the more bizarre properties of negative mass is that which occurs in positive–negative mass particle pairs. If both masses have equal magnitude, then the particles undergo a process of runaway motion. The net mass of the particle pair is equal to zero. Consequently, the pair can eventually accelerate to a speed equal to the speed of light, c. Due to the vanishing mass, such motion is strongly subject to Brownian motion from interactions
with other particles. In the alternative cases where both masses have unequal magnitudes, then either the positive or the negative mass may outpace the other – resulting in either a collision or the end of the interaction.
Although counterintuitive and “preposterous” (Bonnor 1989), all of these behaviours violate no known physical laws. Negative masses are consistent with both conservation of momentum and conservation of energy (Forward 1990), and have been shown to be fully consistent with general relativity in the seminal work of Bondi (1957)."




As for Hossenfelder's comments on Farnes' theory, Farnes responded in the comments with this:

"Jamie Farnes submits the following comment:

"Thank you for writing an article about this. However, I do not think these comments are actually related to the findings in my paper, but rather the papers of others. Your disagreement appears to be with the work of Bondi, who showed that these negative masses are compatible with GR. The comments seem to ignore Bondi's seminal work. I highlight in my paper that spin-2 particles are not at all relevant in this model - I know that is the lens through which you view these equations, but it is just one of many perspectives.

There also seems to be some confusion about section 2.3.3. and the “counterintuitive” finding. This is not actually related to my own work, but is actually an outcome from the cited work of Stephen Hawking and Don Page. It's not counterintuitive because it is wrong, just because that is how the predicted universe would behave!

So the article in its current form gives the impression that it disagrees with my paper, but you are actually disagreeing with far more influential works and authors.

A creation term is also not a "magic fix by which you can explain everything and anything". That is incredibly misleading. It provides very exact and specific well-defined physical properties.

The article also currently reads: "The primary reason that we use dark matter and dark energy to explain cosmological observations is that they are simple." Here you are neglecting the fact that there is ***no physical explanation*** for either dark energy and dark matter. My theory provides the first physical explanation for both of these phenomena in a single unified and intuitive framework. Given the lack of evidence for all conventional theories at present, including those which you frequently highlight, I am surprised that you would not see the advantage to a new idea.

Highlighting the vacuum instability is also completely wrong. This is a feature of the theory, and this is clearly emphasised in the paper. The creation term moderates the production rate of negative mass particles, and prevents this from being a catastrophic event.

Having said all that, I do greatly appreciate the last paragraph, which I think is much more correct. The article also does not mention the abundance of astrophysical observations which my model seems to match - I think to present it as a theory is not really fair or accurate, given the initial matching to the real world."
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https://www.latribune.fr/entreprises-finance/industrie/aeronautique-defense/guerre-dans-l-espace-pourquoi-la-france-doit-massivement-investir-2-3-798299.html
Google translate:
Quote
In the field of space observation, the two Helios 2 military satellites, launched in 2004 and 2009, and the two Pléiades satellites launched in 2011 and 2012, enabling observation by day and night (infrared), will be replaced by three CSO satellites (Optical Space Component). These three satellites will bring significant improvements in terms of accuracy, quality, revisit time compared to Helios satellites. With a theoretical lifespan of around ten years, these satellites, which enable very high-resolution image acquisition, will be launched in 2018 (mid-December), in 2020, and then in 2021.  Intelligence in the space field will be completely renewed. And all the renewal programs of these intelligence capabilities will be launched in 2023.

In telecommunications, the Ministry of the Armed Forces is preparing the Syracuse 4 program, which is a secure communications system. It must allow the maintenance of the permanence of the communications on the national territory and with priority zones of interest, as well as with the buildings with the sea, at any time (peace, crises or major catastrophe). The program includes the construction of two satellites that will replace, by 2021-2023, the Syracuse 3A and Syracuse 3B satellites currently in orbit
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Space Science Coverage / Re: NASA - Dawn updates and discussion
« Last post by Star One on Today at 09:00 PM »
Team finds evidence for carbon-rich surface on Ceres

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A team led by Southwest Research Institute has concluded that the surface of dwarf planet Ceres is rich in organic matter. Data from NASA's Dawn spacecraft indicate that Ceres's surface may contain several times the concentration of carbon than is present in the most carbon-rich, primitive meteorites found on Earth.

"Ceres is like a chemical factory," said SwRI's Dr. Simone Marchi, a principal scientist who was the lead author of research published in Nature Astronomy today. "Among inner solar system bodies, Ceres' has a unique mineralogy, which appears to contain up to 20 percent carbon by mass in its near surface. Our analysis shows that carbon-rich compounds are intimately mixed with products of rock-water interactions, such as clays."
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What I would like to know is how precisely did the stage hit the water target. It seems pretty clear that if it had landed on a hard surface it would have landed upright, so could it have landed on the ASDS?
The stage looked like it was busier staying vertical than aiming for an area the size of an ASDS, so it'd've'd to be something larger like some vacant lot of land.
The center core of the FH Demo did real damage to OCISLY so maybe it's not a good idea to aim a malfunctioning rocket at an expensive vessel.  I suspect this booster could have landed at LZ1 if given the chance, but of course that is not possible.
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