Hot answers tagged

58

First of all, a typical launch window for going towards Mars is about 2.5 hours maximum. As a goal is to send the payload towards Mars, that is one limit to the window. Also, there are a number of other factors affecting a launch. These include: Availability of the range Personnel that are required. A lot of people are required on launch day from quite ...


53

I suspect the wooden sphere is a three-dimensional Helmholtz coil. There are circular groves visible filled with silicone or something similar. The groves contain the Helmholtz coils, one pair for each direction. An electrical current flowing through the coils generates the magnetic field. The Helmholtz pair of coils minimizes the nonuniformity of the field ...


40

The static test wants to be done relatively close to launch day, to minimize the likelihood of anything happening to the engines between the test and the launch. The more conservative procedure is to attach the payload after the static test, but they'd have to lower the rocket, move it back indoors, stack the payload, take it back out and reelevate it. ...


38

EmDrive takes ~300W. You won't get it from a cubesat. You need over a meter of solar panels, or good 56kg of RTG battery. It's been tested on Earth, made with materials and electronics meant to work in Earth ambient conditions: temperature, pressure, radiation. Putting things in space is not as simple as loading them onto a rocket. If they are to work, they ...


31

Rewriting with clarification, I apparently misinterpreted the second tweet. Source still is this twitter feed (from a spacenews.com reporter). The launch insurance doesn't count: SpaceX explosion didnt involve intentional ignition - E Musk said occurred during 2d stage fueling - & isn't covered by launch insurance. (tweet) However, the satellite was ...


28

By the early 1990s the Space Shuttle Program had experienced some close calls with the landing and braking system, especially the tires. Hard data was desired about the response of the tires to various off-nominal situations. To obtain this data, a surplus Convair 990 jetliner was converted into the Landing Systems Research Aircraft by adding an ...


27

There are many different constraints that putting a time window around a launch attempt (even a pad abort) can help manage. Orbital constraints, facilities availability and many more. In the case of a Pad Abort, consider the flight path. Ignite the Super Dracos, get high enough for the parachutes to be effective, and land in the ocean just off the coast. ...


25

You can match the lux count of the sun, in a small area. The amount of solar power that shines on a satellite is about 1300 W/m2 in Earth orbit. This is done at e.g. the ESA Large Space Simulator at ESTEC, in the Netherlands. This provides a horizontal solar beam of 6-m diameter with excellent uniformity and very high long- and short-term stability (...


24

The test they were doing didn’t require parachutes. Data-taking ended right after the capsule separated from the tower. Since the capsule’s behavior after that was not part of the test, it could be an inert item. To extend the test through parachute deployment, the capsule would have to be much more complex with the parachutes, deployment system, and a ...


20

Several issues have been reported informally, mostly in Elon Musk tweets. Not as many cameras turned on as usual Storage on site was damaged, and not all data was uploaded during test This fueling event, for a static fire, was a really routine thing by this point. They thought they had fueling down pat. The last fueling accident like this in the US was ...


20

To add to Uwe's answer – Aluminium is a bad material to wind coils around (like conductors in general) because any change in the current will for a while be “shadowed” by eddy currents. This can to some degree be mitigated by laminating only small sections, but this isn't as easy with aluminium as it is with wood. And even with constant magnetic fields ...


19

I can answer the Shuttle part. The test in question was the Mated Vertical Ground Vibration Test (MVGVT). Here's how the stack looked in the test stand. Five configurations were tested Liftoff First stage (SRBs attached) early, mid, and late 2nd stage For the launch testing, the SRBs stood on hydrodynamic supports which "provided the vertical support ...


17

Another minor factor in the timing of the launch is avoidance of other spacecraft and orbiting debris, as exemplified in a note posted on the Spaceflight Now mission update page for this test flight at 02/06/2018 13:47: There is one collision avoidance cutout in the remainder of today's launch window at 3:56 p.m. EST (2056 GMT). The Falcon Heavy cannot ...


16

I can answer this part "Has this same (or similar) design always been used for such tests?" In the early days of the program Shuttle would occasionally do a pad test where the main engines were fired briefly. During this test (and at all other times) the Shuttle/External Tank/Solid Rocket Booster stack was held down to ...


15

From the article: Tuesday’s launch was more focused on testing the launch abort system itself. The parachutes on Orion have been tested 47 times.


15

Probably highly relevant here is the concept of the failure curve where parts will generally fail either at the start or end of life. Some engine designs may be such that they do not have much of an early failure tail but shallow (unpredictable) end of life tail, these would not be test fired. The Apollo ascent engine might qualify. For a more conventional ...


14

Launching on a risky booster, is risky. You can define a risky booster as: First launch of a new booster. Return to flight after a failure. Booster with record of failure So you feeling lucky punk? How much development money are you willing to risk on any of those cases? Why did ISRO take the risk on the GSLV launch and Angara5 won't? I would assume ...


14

For simple stability, you need the center of gravity to be in front of the center of pressure. You can find the center of gravity by hanging the rocket from a string with a loop that slips along the body. The balance point is the center of gravity. You should measure it twice, once with a fresh engine installed, parachute packed, wadding, etc, (launch ...


13

The new test stand is for the full Falcon Heavy. Every Merlin is tested on the stand before being combined into a full F9 stage. It is reasonable to extrapolate this out to the three core FHeavy. The benefits of a 3 core test are unclear. The Falcon Heavy was planned to have cross feed capability, where fuel would flow from the two external boosters to the ...


13

Currently unclear According to the Verge: It's possible that the [static fire] test could come early next week. But the Falcon Heavy’s launchpad is located at NASA’s Kennedy Space Center, and limited staffing at the site could pose a problem. SpaceX told The Verge on Friday that the company is not expecting the shutdown to affect its operations. ...


13

It is indeed difficult to find information on this building. As you can see in the photo below, it was part of a massive test facility at Marshall Space Flight Center: (Overview of MSFC; Mike Jetzer/heroicrelics.org) Some details of how the test stand worked can be found in the nomination form for the US National Register of Historic Places Inventory: ...


12

That is an anechoic chamber. An anechoic chamber ("an-echoic" meaning non-reflective, non-echoing or echo-free) is a room designed to completely absorb reflections of either sound or electromagnetic waves. They are also insulated from exterior sources of noise. The combination of both aspects means they simulate a quiet open-space of infinite ...


12

It's got to be hugely expensive to transport and erect a Falcon even if you don't intend to launch it. The potential for damaging part of the rocket in the test makes it even less attractive. Why use a real rocket if a truss suffices? After Apollo's first abort test from a low platform in the desert, they also did several in-flight abort tests by ...


12

This is not a complete answer as I do not know the status of the parachute development, but here are some reasons a parachute is not needed: Ejected Data Recorders: These ~20 data recorders, literally Raspberry Pis with parachutes and waterproofing, all get the complete telemetry data from the test. This is made up of accelerometer, gyroscope, magnetometer ...


11

We might, it depends on the scale of the project, and if someone proposed a proof of concept mission and is ready to finance it. For a small scale technology demonstration mission such as the ones regularly performed aboard the ISS, it could be, for example, proposed through CASIS as a Physical and Materials Science R&D project, but it likely won't win ...


11

The Transporter/Erector can only lift a complete first and second stage. That is not to say it requires the payload, but to say it requires the second stage. Taking your question to next logical step, why do a static fire of the first stage engine with a $20 million second stage on board? Well, they need it so the T/E can grab it and hold the complete ...


11

The engine controller is a computer mounted on the SSME which monitors and controls the engine. It, for example, takes throttle commands as a % of power level from the vehicle and translates them into control commands for the engine valve control loops. The SLS engine controller is a new hardware device and presumably new software as well. The pogo ...


11

Here's an official response: NASA has already fully qualified the parachute system for flights with crew through an extensive series of 17 developmental tests and 8 qualification tests completed at the end of 2018. Test data from 890 sensors was sent in real-time to ground sites as well as recorded on board by 12 data recorders. The 12 data recorders ...


10

Yes, some testing and all launches except for those critical to national security have to be postponed. By now, I’m sure you are well aware that a budget agreement was not reached last night resulting in a government-wide shutdown effective today. Many in our workforce recall the impacts of the 2013 shutdown, and now 5 years later, we find ourselves in ...


10

Purging is done to remove residual fuel from the lines. This is normally done using nitrogen gas. https://www.grc.nasa.gov/www/retf/textFiles/lessonsRocketEngineTesting.html Residual fuel and oxidiser represents a combustion hazard - it could leak out or evaporate and start a fire. Also, if your oxidiser is something like nitric acid or dinitrogen ...


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