17

Regarding proximity, we'll need a good database first. For example, Eric Johnston publishes on a SatSig.net page a list of satellites in Geostationary Orbit (GEO) that was last updated on 21 Feb 2014, so fairly recent. I couldn't find more complete list, but this individual has been upkeeping the list for a fairly long time (some older pages where he ...


15

Here is a basic rundown of the effects of the shutdown: 97% of NASA was furloughed. That is the highest percentage of any agency listed. The only known NASA direct operations are those related to Mission Control, and astronauts on the ISS. Everything else was shut down completely. JPL and APL are technically NASA contractors. This is really good news as ...


12

NASA's standard desktop office computer configuration is Windows 10 with Microsoft Office. This software is provided agency-wide by the NASA Shared Services Center (NSSC). Here is an excerpt from the NASA-STD-2804 Fall 2017 MINIMUM INTEROPERABILITY SOFTWARE SUITE requirements document (the latest version available from the NSSC website to the general public)...


11

Weight distribution would be be the main reason. The Shuttle stack (or Saturn V stack) empty, weighed an immense amount. Shuttle more so, since the SRB's were full during movement. (Can't fuel a solid rocket on the pad). The SRB's weighed 1.3 million pounds each ready for flight. That is really an immense amount, over a small area. The tracks of the ...


10

To boil this down to a simple answer is difficult, but here's some of the factors that are required to make this assessment. First of all, the question comes, what is your satellite is specified to. When you build a satellite, you specify a level of radiation tolerance you desire. If you have more than that level of radiation, then you have to start taking ...


9

In theory, GEO locations are subdivided into fixed "slots" of 2 degrees longitude (or 1470km of orbital extent per slot). Within a slot, the individual satellite must confine itself to a "box" of 0.1 degrees longitude (or something like 70km). Naturally, this is not always a case in reality. Satellites do drift across slot boundaries every now and then. ...


9

Safe mode is a software state that is initiated by a detection of some inability of the system to do what it has been asked to do. There are many, many ways that can happen, such as insufficient power, inability to determine attitude, detection of a failed component, such as a reaction wheel, or a software fault or crash. In safe mode, only the minimum ...


9

The biggest single change in the Houston Mission Control Center (MCC) occurred in the late 1990s. This was the change from a mainframe based system architecture to a workstation based system with a client/server architecture. The project was led by John Muratore and it's discussed at some length in his oral history. Several of the papers in the Control ...


9

Is it still in use today? Considering the sourceforge site for a DRAKON editor shows over 100 downloads this week and it was last updated June 1st, 2015 I'd say that project is active, which strongly suggests the language is still in use. Are there any space programs still using the language today? From wikipedia: The work was finished in 1996 (3 ...


8

ISS operations plans re-boosts to have roughly 90 days before the vehicle gets too low. This doesn't mean that re-supply missions are 90 days apart since the ISS is often boosted much higher than this minimum level -- especially post-Shuttle. But, it gives you a rough idea of the timeframes involved. I suspect that other consumable margins are larger than ...


8

Most satellites have some sort of a safe mode, a mode the satellite enters when it is having difficulties with certain things. The exact nature of the safe mode varies from satellite to satellite, but in general, it is a lower power state, thermally stable and power positive, turns off science instruments, and relies less on absolute pointing. I can say ...


7

Virtually all systems that do this use some sort of a continuous process. The typical process is something like this: A large change in momentum is required. The momentum change is handled by the reaction wheel. Reaction wheels basically work by changing the rotation of the spacecraft. You can think of it like standing in the center a roundabout and turning ...


6

Besides the issues already mentioned, it's also caused some morale problems. Unlike what user6972 claims, we did not have 'vacation'. Some were designated as essential employees, and were required to work through the shutdown. Some were sent home, but unlike with a vacation, you couldn't really go anywhere as you might be called back at any time. In my ...


6

The Kennedy Space Center Story, written by NASA in June 1970, NTRS document 19710024295, p. 29 describes the options that were considered, and the reason for the final choice: The scheme by which to transport launchers and assembled Saturn V vehicles was carefully explored by NASA engineers. A barge canal system was investigated. Models were tested in the ...


6

The RMS had six joints. (It is shown here holding the Orbiter inspection boom.) The rotational position of each joint was measured by internal 16-bit optical encoders giving a precision of 0.0055 deg. However, since no mechanical device is perfect, corrections (known as "encoder biases") for the differences between "encoder zero" and "mechanical zero" were ...


4

I had the distinct honor of working for John Muratore on two distinct projects. One was the X-38. But before that, I worked on developing advanced software for his Real Time Data System project. The RTDS project started in 1986 when Muratore saw the archaic structure of Mission Control. The primary goal of the project was to transition from a single ...


3

Another thing to consider is that (most of) Kennedy Space Center launch pads are significantly elevated above average ground level, whereas Baikonur Cosmodrome is flat, instead having large trenches dug underneath the pad. Compare KSC: with Baikonur: Where the Russians ride over smooth, level terrain, the Americans have to overcome this elevation as the ...


3

I looked into this a while ago. It's easy to get bogged down in the details, because although the data is very public, there are so many parameters for every mission that I found it hard to get a straight answer. I used these points to "dumb down" the question: Seeking maximum time between launch of one mission and the next mission Manned and unmanned ...


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