PakledHostage

T minus 1 hour. NASA TV's coverage now involves interviews with mission scientists and engineers in between just silently watching the immobile rocket...

I don't want to start any arguments, but it would certainly benefit you to back up your claims with some numbers and facts if you start a post with that much snark... Challenge accepted (on behalf of Nibb31): Assumptions - Delta-V expended by the space shuttle is typical of launch vehicles - The shuttle's SSMEs produce a constant combined thrust of 1125000 lbf at 100% throttle (ref: http://www.nasa.gov/returntoflight/system/system_SSME.html) - The shuttle's SSMEs have an ISP of 455 seconds (ref: http://en.wikipedia.org/wiki/Space_Shuttle) - The SRBs produce a constant combined thrust of 5300000 lbf (ref: http://www.nasa.gov/returntoflight/system/system_SRB.html) - The SRBs have an ISP of 269 seconds (ref: http://en.wikipedia.org/wiki/Space_Shuttle) - The launch profile given in the NASA press kit for STS-30 is typical of launch vehicles Per the launch profile given in the NASA press kit for STS-30, the shuttle reaches 37000 feet altitude in 1 minute, 2 seconds. It is travelling basically straight up at 435 m/sec by that point. (Note: Even 30° off vertical is still 87% straight up...) Using the values I gave above, I approximated the delta-V expended during 4 phases of flight, from launch to MECO: 0 - 30 seconds, throttle = 104%, Delta-V ≈ 0.47 km/sec 30 - 62 seconds, throttle = 65%, Delta-V ≈ 0.56 km/sec 62 - 125 seconds, throttle = 104%, Delta-V ≈ 1.75 km/sec 125 - 511 seconds, throttle = 104%, Delta-V ≈ 6.79 km/sec Total delta-V expended to MECO ≈ 9.56 km/sec. Note that this total delta-V is almost certainly low. The SSME's Isp is certainly higher in a vacuum than it is at 1 atm, but I used the values for 1 atm to be conservative. (i.e. a lower overall delta-V to orbit increases the relative benefit of launching from a carrier aircraft.) Let's assume that a launch vehicle is dropped from a carrier aircraft at 37,000 feet going 235 m/s (Mach 0.8) horizontally. Let's then be generous and assume that the launch vehicle has wings that allow it to redirect all of that speed vertically without any expenditure of delta-V. The weight of those wings will affect payload capacity however. The extra structural weight that will be required for the tank to sustain lateral stresses during climb to launch altitude and during the turn from horizontal to vertical will also affect payload to orbit. In that case, your rocket will need an additional instantaneous delta-V of 200 m/s to match the shuttle's speed at that altitude (i.e. accelerating from 235 m/s to 435 m/s requires a delta-V of 200 m/s). Per the estimates in the table above, it cost the shuttle 1 km/s of delta-V to reach that altitude and speed. Net benefit of launching from altitude is therefore on the order of only 0.8 km/s... That's 0.8 km/s out of a total of close to 10 km/s required to reach orbit! Also, reinforcing the rocket so that it can sustain bending loads is non-trivial. According to NASA astronaut Don Pettit's article The Tyranny of the Rocket Equation: Admittedly the shuttle's main tank is an extreme example, but one needs only to recall the recent in-flight break-up of a Russian Proton rocket to understand that even conventional rockets don't handle transverse stresses very well… That doesn't mean it can't be done, but it means that launching from a carrier aircraft isn't as obvious an advantage as some might think.

I was trying to be helpful rather than take this thread off topic, but I am certain that PDT is 7 hours behind GMT while PST is 8 hours behind GMT. Kryten gave the launch time as 03:27 GMT. 7 hours before 03:27 is 20:27, isn't it? It has been along day though...

Sorry, teasing my compatriots from Saskatchewan who stay on standard time all year (CST), rather than switching to daylight savings time in the summer.

Who knew Darth Vader was a stubblejumper? For the benefit of those who don't live in Saskatchewan, I've converted the launch time that Kryten gave for the rest of North America: PDT - 20:27 MDT - 21:27 MST - 20:27 CDT - 22:27 CST - 21:27 EDT - 23:27 ADT - 00:27 NDT - 00:57

Coincidentally, I still have a printout of the original JPL press release from September 20th, 2002 folded inside the front cover of my celestial mechanics textbook. The press release number was #2002-178. A quick Google search on that number returns a link to the document in the JPL archive. Anyone who's interested can find it here: http://www.jpl.nasa.gov/news/news.php?release=2002-178. It is an interesting read.

There's not much to say about this topic that hasn't already been said, but I do think the lowly Slug has been overlooked. According to Wikipedia, the Slug is: I saw that Bunsen mentioned it, but nobody seems to have noticed. I always thought that the Slug was the "official" imperial unit of mass? (I was raised with the metric system so I don't know for sure...)

I stand corrected. Mea culpa.

I was referring specifically to the manned portion of the Chinese space program, and I think Michael Kim was too. The more recent achievements are very impressive, and I am looking forward to following the Chang'e mission later this year. The optics of the manned program, however, is that they merely followed the path of least resistance to placing a person in orbit by purchasing Russian technology.

Then maybe you can help those of us on this side of the cultural divide better understand China’s motivations? I did a bit of searching around online and found a United States Defense Department briefing to the US Congress titled China’s Space Program: An Overview. In it, they quote a Chinese government “White Paperâ€Â, published in November 2000. The paper outlines the Chinese government’s goals and guiding principles for the space program. The first of these is: That would seem to support what you’re saying, but further along in the briefing note, they state that: and The optics are that, while China may have developed some manufacturing technology in order to achieve the goal of launching manned missions, they basically just purchased the technology from the Russians. Why would anyone bother to do that other than for the status of being among an elite club of nations who have done the same? After all, there are easier and cheaper ways of developing manufacturing technology.

I 've only watched the first couple of minutes so far but it looks really well made. I'll finish watching on the weekend. Thanks for sharing.

And what kind of misrepresentation are you perpetuating exactly?! The UK parliament's Science and Techology Committee cleared the CRU scientists who were at the centre of "Climategate" of any wrong doing in their report on The disclosure of climate data from the Climatic Research Unit at the University of East Anglia. Between the original peer reviews and the inquiries that followed "Climategate", the CRU's work must be among the most heavily scrutinized body of scientific research anywhere, yet its veracity remains intact. From the UK Parliament's Science and Technology Committee's website:

UPDATE I have posted the latest version (v 1.0.21.03) to SpacePort this morning. I have tested my changes using AviatorDSB's persistence file as well as with my own persistence files. The bug seems to be fixed. Hopefully it won't rear its ugly little head anymore. Thanks, everyone, for your patience while I worked to resolve this issue.

@blenderman: I agree that it is a good idea. I won't make any promises, but I will think about how I could implement it. UPDATE I have fixed the bug that people were reporting, but once again I can't log in to SpacePort. I had the same problem about a month ago and Rob (N3X15) helped me get access to my account, but I seem to be locked out again. I'll send another email, but I don't expect to hear back for several days because, according to the "Oh the places we'll go! blog article, the guys are all out of the office into next week. Until then, please accept my apologies. You can still avoid the bug by only having one craft at a time carry the receiver, or reverting to the old method of using a unique acronym in the names of all of your satellites (change the "GNSSAcronym" parameter in the Figaro Receiver's Part.cfg file to match the acronym you are using if you choose this work around).

Since we seem to be firmly off topic, I thought I'd add that the most realistic "nightmare scenario" is that we discover something like comet C/2013 A1 Siding Spring on a collision course with Earth. For a brief period after it was discovered this past January, it was predicted that comet C/2013 A1 could impact Mars at a relative speed of 56 km/second. The comet was only discovered in January because it is an Oort cloud comet that is on its first pass through the inner solar system in recorded history. The current best guess of its size is 4 km diameter, but initial estimates ranged as high as 50 km diameter. The most recent trajectory calculations predict that it will miss Mars, passing between 37000 km and 210000 km from Mars' centre on October 19th, 2014 at 18:41 UT. In the event that a comet like C/2013 A1 Siding Spring was discovered to be on a collision trajectory with the Earth, we may only have a year or so to prepare.

I wondered if anything would have been visible from the LA area or the Channel Islands? Maybe with a telescope? From the graphics, it appeared to have been launched on a south easterly trajectory.

The same is true of laser gyros. They measure Doppler shift in laser light to determine rate of rotation. Laser gyros are accurate enough that they can precisely measure minute variations in the Earth's rotation rate. The data is used, in part, to improve the accuracy of the GPS system.

Launch delayed to 11:03 PDT

Here's a video from a previous Vandenberg Delta-IV Heavy launch while we're waiting for today's festivities:

His location tag shows he lives in California and his avatar looks a bit Rastafarian... While I'll agree with you that the majority of urban westerners aren't, there are plenty of humans who are perfectly capable of surviving in the wilderness. And those few members of our species who would be privileged (?) enough to occupy such a shelter would certainly seek the benefits of both technology and the expertise of those who do have such survival skills. Sounds a bit like building a colony on another planet. Except that we don't have the added complexity of transporting our technological infrastructure there first. If we can’t do it here, we can’t do it anywhere else either.

The Toba Catastrophe about 70000 years ago is a good benchmark of our resilience as a species. There are multiple streams of evidence that suggest that the global population of humans was reduced to about 6000 to 10000 individuals by that eruption, yet we recovered to span the planet using only stone-age technology. Edit: I did some further reading on the Toba Catastrophe, and it seems that the idea that the Toba eruption was the cause of the apparent human population bottleneck about 60-70 thousand years ago is falling out of favor.

Can you please provide a reference? I looked for one but couldn't find anything supporting your claim. Something that significant should be well documented. And don't forget that Shackleton and his men were still able to live off the land to an extent.

This reminds me of the Biosphere-2 experiments in the 1990's. The Wikipedia Biosphere-2 article has a bit of a summary of the "missions", and the problems that they encountered.

Thanks guys for the answers. I had read about how an increased neutrino flux can precede visible supernovae, but I just never gave it very much thought until this thread inspired me to ask the question.