Not only is Hubble back online after outage, it's already taking photos of the cosmos The Hubble Space Telescope is back in action doing what it does best – capturing stunning images of the universe – after more than 50 NASA engineers worked hundreds of hours to get the instrument working again. After activating redundant components within the orbiting observatory on Friday to clear a hardware glitch, the …
>Whoever comes up with a reuseable space runabout that can do work more or less anywhere it is needed will dominate the space business.
It's bucks, not Buck Rodgers, that drives this. The resuable space shuttles cost $209 billion/848 launches = $240 million per launch. It's a nice idea, but it isn't resuable that is needed, it is economically reusable.
This post has been deleted by its author
The whole point of reusable craft is to acheive economy, otherwise why bother?
The objective as you point out is to create an economically feasable system that is also versatile.
The shuttle was a start but using tons of discarded metal along with the shuttle itself at each launch could never be regarded as a permanent solution.
Musk has started in the right direction by creating recoverable, reuseable boosters.
Now it needs refining and further development.
The shuttle was a start but using tons of discarded metal along with the shuttle itself at each launch could never be regarded as a permanent solution.
The only thing discarded in a shuttle launch was the fuel tank. The solid boosters were recovered and re-used.
"The only thing discarded in a shuttle launch was the fuel tank. The solid boosters were recovered and re-used."
The problem was the amount of effort and cost of refurbishing the boosters and shuttle for another launch. Musks launchers appear to need minimal cost and refurbishment (if any!) to make ready for another launch which is the vast majority of the cost savings.
All you need is to launch people to where the telescope is and have them spacewalk, then return safely to Earth. The shuttle's cargo bay is irrelevant to a Hubble repair mission, any old capsule paired with any old human rated rocket engine will do. It is that latter that the US has been without since the shuttle was mothballed.
Nice pics. Minor thing though.
A star can appear in multiple places in the sky at the same time. It is not one dot of light per physical star, it is many dots of light per physical star. You may be looking at the star at multiple times during its life each in a different place in the sky. The same star, multiple places. Even completely different directions.
Why?
Very simple: space is curved, light can follow muliple curved paths to reach your eye. Each path can take a different time to loop back. The same star producing specs of light heading out in different directions forming multiple curved paths back to you, arriving from multiple directions.
Since each ray of light you perceive as if it travelled in a straight line. So you perceive each dot of light as a *separate* star in a separate location in the sky, not as a single star, even though all the rays of light came from that star.
Space is curved, you've observed gravity lensing, you can see light follows a curve, and so it is curved. Any non-zero curve means the universe is finite, light cannot travel in a straight line forever without bending back as it does so, in a *finite* universe.
Ahh but you say, its very very nearly straight, so we can ignore the curve. Nope, you have an observation of a *finite* universe, "the observable universe".
I'm going to put it to you that the *observable* universe IS the *finite* universe. That the observation limit you're hitting is the same limit caused by bending of space. It is *observably* curved, and you've *observed* it. In other words, you cannot simply assume, it's 'for all practical purposes' straight with negligable bending, because the bend is enough to observe, and so the light bend is observable.
Hence you can observe the same star(s) appearing in multiple places in the sky at the same time.
As Disaster Area's earnings require hypermathematics, their chief research accountant was named Professor of Neomathematics at the University of Maximegalon and in his Special Theories of Tax Returns he proves that space-time is "not merely curved, it is, in fact, totally bent."
This is what happens when somebody gets a few facts and tries to extend them using the wrong kind of physics.
Yes, space/time is curved but not as curved as you seem to think.
Yes, if you go in a straight line you'll end up where you started - but - due to the degree of curvature you'd have to go a very long way, many multiplies of the diameter of the observable universe.
If what you said was true we would be unable to resolve any stars, they would all be smudged blurs and not the point sources we do see.
So, obviously you're a crank (are you always the same anonymous crank, or are there multiple ones? Who knows? Who, really, cares?). but in case there are people who aren't cranks.
Yes, there is gravitational lensing, and yes, this is observed, and yes, it often results in multiple images of the same object. The gravitational lensing which we observe is caused by relatively small concentrations of mass which deflect light from objects further away from them. 'Relatively small' here might mean actually quite small (black holes or other compact objects like stars), right up to clusters of galaxies: things which are small on cosmological scales.
A separate thing is the large-scale structure of the universe. There's a thing called the 'cosmological principle' which pretty much comes down to 'we're not special'. And implication of that is that, when looking at the universe on large scales, everyone should see the same thing, wherever they are. The Earth, or the Solar system or the Milky Way was not specially put in some special place. In particular, since we observe that the universe is the same in all directions to a very good approximation that means everyone does, and you can conclude immediately that the universe, on large scales, must be both isotropic (same in all directions) and homogeneous (same everywhere).
There is precisely one metric (model of the shape of the universe) which is compatible with the cosmological principle, which is the FLRW metric. So assuming the cosmological principle is true we must assume that the FLRW metric describes the universe on large scales.
The FLRW metric lets you do a clever thing: you can essentially 'factor' spacetime into spacelike and timelike bits: you can cut sections through the universe at a constant cosmological time. And you can then ask what the curvature of those sections is and wonder about what the corresponding large-scale topology might be.
There are in fact three cases: the universe could have positive curvature, in which case it is spatially finite, and the whole 'seeing the back of your head' thing could happen. The universe could have zero curvature in which case it is either spatially infinite or there is global topological weirdness, or it could have negative curvature in which case it is also spatially infinite barring global topological weirdness.
Well, it turns out we can measure this spatial curvature in at least two different ways, and within experimental error it seems to be zero: the universe is spatially either flat or very close to flat. If it actually is flat or if it has negative curvature, then it is either infinite or has weird global topology.
And this debunks your silly theory: we know the radius of the observable universe (it's about 14 Gpc), and this radius is farcically too small to be able to see right round the universe even if it is positively curved, which we don't think it is. So no, there is not enough curvature that we can see right round the universe, not anywhere close.
> Any non-zero curve means the universe is finite
Only if that curve is constant along its entire path, or rather non-zero AND a monotonic vector.
Your extrapolation to multiple points of destination light from single source, outside of gravitational lensing, also requires that these vectors and/or rates of curvature along each path be unassociated with one another.
I am unable to think of a sensible candidate substratum which would deliver such a result.
NASA Engineers don't just design systems that work, they sit down and ask themselves what could go wrong and what can be done to make sure it doesn't happen, or if it does happen, how can it be fixed. Hubble's been running for 30 years now with only a few minor issues and Voyager 1 is still sending us information after 40 years and 14 billion miles.
Per my comment in an earlier thread: beancounters could never have allowed this; their mindset is if it didn't fail at the expected design lifetime, it was overengineered and therefore consumed too many beans.
---> for the engineers. The beancounters get nothing.
NASA Engineers don't just design systems that work, they sit down and ask themselves what could go wrong and what can be done to make sure it doesn't happen, or if it does happen, how can it be fixed.
Just imagine where we'd be now if they had used "Agile". They wouldn't even have had those 40-year-old docs to look at.
Hubble is less impressive when you remember it came after several decades of space telescopes,
There have been optical spy satillites since the 60s, - keyhole series -
They did not have the benefit of human intervention to fix the mirror.
It can be cheaper to launch one cheap telescope every few years rather than to over engineer one to make it last 30 years. That redundancy adds weight and complexity. Weight explodes the launch cost.We could engineer cars to last 30 years, but we actually engineer for 10 years. We want the benefits of newer technology.
Hubble was so expensive it required budgets from ESA and NASA. It is a legacy of all that is wrong with NASA. KISS - keep it simple - keep it cheap. The you can afford to fail.
I'll just point out here that Hubble is 11,110kg. JWST is 6,500kg. Both of them, in 2020 dollars, seem to have cost about $10 billion.
I'm not sure if it's clear how long JWST will last, but it's not 30 years.
The reason these things are expensive is because it's very expensive to build a telescope which is actually useful to astronomers and fly it: such a telescope, almost by definition, has to be have capabilities that beat anything that currently exists.
An Ariane 5 could easily have launched something as heavy as HST into LEO (the ES configuration can put more than 20,000kg into LEO). The launch cost for an Ariane 5 is about $180 million: about 1.8% of the cost of the telescopes. Launch cost and its dependency on mass is not a big factor in the cost of these things.
Almost everything you say is just wrong.
I wonder what kind of capacitors they use? Standard electrolytics can dry out and fail over time here on Earth in normal atmospheric pressure. I wonder what happens in near as dammit zero pressure? I'd expect a standard electrolytic would just explode, or at least leak very early on. I'm guessing the boards are encapsulated at the least.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
