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21

At least for some vehicles, "dynamic pressure is closely monitored" is not correct. You need to have an air data probe to actually monitor it, and not all vehicles do. Shuttle: Dynamic pressure was not actually measured1 during ascent so "Max Q" was not either. The magnitude and time of Max Q was predicted by prelaunch simulations, and ...


21

It's eight or ten seconds from the sudden flare at the base of the rocket 'til it hits the ground and actually explodes. I'm not an expert, but I don't see any particular reason why power to the guidance systems would have been off-nominal immediately after the initial flare, and if the controller were watching the power readouts instead of the visual, he ...


14

Avionics is short for "aviation electronics"; on an aircraft it can include computer equipment, communications, guidance and navigation, radar, etc. "Avionics power nominal" implies that the rocket's guidance computers were getting the right amount of electrical power. Presumably the Antares rocket's avionics power went off-nominal a short time later, ...


13

I asked NASA via Twitter about it hoping they answer it during the Orbital Sciences/Cygnus-2 Post-Launch News Conference, but Stephen Clark from SpaceflightNow.com beat me to it and asked Frank L. Culbertson, Jr., Vice President and General Manager of Orbital's Advanced Programs Group, this very same question over the phone. It can be seen in this video ...


10

They were planned separately. It takes a long time to plan and execute a launch, and both Antares ORB-3 and Progress M-25M had their launch dates set months ago. To see how far ahead some of these launches are planned look at: http://www.spaceflightnow.com/tracking/ For instance in August next year Progress 60P and SpaceX CRS-8 will also launch within a ...


9

A solid rocket can stop early, and typically in a situation where they rely on it, they will have extra fuel, and just cut off the rocket early. This is very commonly done for missile systems, which have to be very flexible, and be able to fire with little time, and near other people. In addition, they can correct for other wrongness by moving the thrust ...


8

Solid fuel does make sense for a top stage, a so-called kick stage, the most notable example being the Star family. A kick stage has only smaller or similar gross mass as the payload it propels, which means that the weight savings from a high-ISP fuel are limited – you're in either case only getting a small bit of extra Δv. In other words, you're within in ...


8

The ISS is currently supplied (or was) by the following vehicles: Space Shuttle - retired ESA Automated Transfer Vehicle (ATV) - last one has flown - retired JAXA H2 Transfer Vehicle (HTV) - which has only a few flights left before retirement Russian Progress - cargo, fuel, air, water - active Russian Soyuz - crew, very minimal cargo US SpaceX Dragon - ...


6

I want to expand on the excellent Russell's answer, which I gladly upvote. I am by far not an expert in spaceflight either, but I happened to take part in a lab operation emergency handling, and used to carry a pager with a huge internet operator. Any such event, a space launch more so, but also industrial or even computer operations, has a rehearsed plan ...


5

There are ways to measure dynamic pressure, and in aerodynamically complicated spacecraft (like the shuttle) if measured on its three four "nosecones" it could conceivably occur at (at least somewhat) different times in different places. And yet when we watch a launch there is a specific time when the announcer calls out "Max-Q!" at which ...


5

I'll just start with some things that came to my mind. Not planning to provide a complete list here. You can look at the craft itself prior to and shortly after launch. Was there any leakage or jets of propellant where there shouldn't be any? For example, smoke was visible during the final launch of the space shuttle Challenger. Comparing the video to a ...


3

Cygnus has two main components. The Pressurized cargo compartment is built by Alenia-Thales in Italy. The same folk who built the pressure vehicles for most of the ISS modules and the ATV. The bus or service module is based on a satellite design Orbital had on the shelf. It is based on GEOStar Satellite Bus and the Dawn spacecraft. Thus the interface ...


3

I was looking for possible answers for an US-sourced engine, and was going to float the RS-27A as a possibility (though it's been out of production for over a decade) -- you'd probably need a cluster of 4 to substitute for a pair of AJ-26. Then I saw this reference to the Aerojet Rocketdyne AR-1 proposal. At 2200 kN, a pair of them would be up in the RD-180 ...


3

In Dec 2014, Orbital selected the Russian Energomash RD-181, which is basically an export version of the RD-191 used in the Angara booster. This is also a LOX/kerosene engine, derived from the RD-170. The RD-170 is a 1.6 MLbs thrust engine used on Zenit boosters (which were initially strap on boosters for Energia) that has 4 thrust chambers. The two ...


2

The second engine definitely stopped at the time of the initial explosion. More accurately, its plume tapers off in 4 frames, or about 0.13 seconds, of the video. The reducing plume is straight and not discolored. This is much too slow to be due to direct damage from the adjacent explosion, and the "neatness" of the shutdown implies that it was a ...


2

In this closeup, it's pretty obvious this is an air hose. They are routinely used to control the temperature inside the fairing. Here's a similar system on a Vega rocket (for the LISA Pathfinder launch): LISA Pathfinder, ready for launch. In this image, taken with an ultra-wide angle fisheye lens on November 19, the spacecraft is hidden from view, ...


2

This is speculation - not a complete answer. The smoke blowing off the pad made me take a gander at http://www.wunderground.com/weather-forecast/US/VA/Wallops_Island.html for today July 13th, 2014 AD The graph shows the barometer falling between 1213 through 1320 - the time-frame corresponding to the launch. There is a corresponding rise in the wind-speed ...


2

Generally speaking, you want as few moving parts as possible, unless the extra parts add a useful redundancy. More moving parts = more things that can go wrong. Some examples: intercontinental aircraft used to require 4 engines, because that meant they could lose one and still make it to the other side of the ocean. These days jet engines are reliable enough ...


2

The marine zones should be in the USCG local notice to mariners http://www.navcen.uscg.gov/pdf/lnms/lnm11012017.pdf (that doesn't have an example, but it should...)


1

Here's an example from a June 2018 (planned) launch of Falcon 9. See page 9. Googling for the two phrases: "Local Notice to Mariners" "Eastern Range" is an effective way to find Florida launches.


1

The Falcon 9 uses an RP1-LOX engine developed by SpaceX called the Merlin. The thrust is significantly lower (using a Merlin-1D) than a RD-180 (155,000 lb*f vac. vs 933,400 lb*f vac.), but they are smaller (2.92m high x 1.67m diameter x 630Kg vs 3.56m high x 3.15m diameter x 5,480Kg) and the Falcon 9 uses nine of them. Eye balling the diameters you could ...


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