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130 votes
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How is stacking oranges in 24 dimensions related to receiving and decoding signals from the Voyagers?

All the different data words a transmitter can send and a receiver can detect can be imagined as dots arranged in a large space. Selecting a data encoding for error detection and correction is about ...
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50 votes
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Can we write with chalk on blackboard in space?

There's no scientific reason against using a chalkboard, zero gravity isn't an impediment as making a mark is dependent on pressure between the chalk and the board. The reasons for not using chalk are ...
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41 votes
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Gagarin not ejecting from capsule

Initially, the USSR insisted that Gagarin had landed with the spacecraft, because of requirements for FAI certification of spaceflight records: One of the stipulations for spaceflight requires that ...
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40 votes
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What are some of the obsolete technologies that space agencies used in day-to-day work during the 1960s?

Everything has changed in the last 50+ years. Every group working on space exploration had secretaries, lots and lots of secretaries, about one for every four to ten technical employees, plus many ...
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36 votes

Why do Canopus Star Trackers track Canopus? Why not so Sirius?

As someone who has designed a Canopus tracker, it's really very simple. The Sun is generally the easiest thing for a spacecraft to orient to, regardless of orbit or location in the Solar System. So, ...
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  • 1,808
35 votes

Can "engine" and "motor" be used interchangeably in spaceflight? Are there any cases where they can't be?

"Motor" by convention refers to a solid rocket, "engine" by convention to a liquid rocket. There can be exceptions. ...the word "motor" is as common to solid rockets as ...
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34 votes
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What is this pin on John Glenn's suit jacket?

It's the Project Mercury / Mercury Seven emblem. The astronauts went under the name Mercury Seven, and the program design includes the number seven. The symbol represented around the seven is the ...
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33 votes
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What did Charlie Duke mean by "down on the ground"?

Based solely on my long experience working behind the scenes in the Mission Control Center (as an instructor, not a flight controller) "on the ground" is unlikely to mean anything other than ...
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31 votes

Why do Canopus Star Trackers track Canopus? Why not so Sirius?

This answer assumes that the spacecraft is in an orbit which is mostly aligned to the ecliptic plane. A target, whose orbit is also close to the ecliptic plane, can occasionally go in front of the Sun ...
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26 votes

Can "engine" and "motor" be used interchangeably in spaceflight? Are there any cases where they can't be?

According to Wikipedia, they are effectively interchangable: Motor and engine are interchangeable in standard English. In some engineering jargons, the two words have different meanings, in which ...
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24 votes

Can we write with chalk on blackboard in space?

@GdD's answer is complete, but I'll elaborate on the chalk dust. They pretty much can't even have bread or cake on the ISS due to the crumb production; a manual chalk-dust generator would be a ...
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23 votes
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Has any piston machine been used on a space mission?

Apparently JWT uses piston pumps in its Cryocooler system: The only moving parts in the cryocooler are the two 2-cylinder horizontally opposed piston pumps in the CCA, and by having horizontally-...
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21 votes

What are some of the obsolete technologies that space agencies used in day-to-day work during the 1960s?

I would say Core Rope Memory The Apollo Guidance Computer was one of the first computers to made use of integrated circuits. It was light and small enough (roughly 70 pounds) to fit in the CM. One of ...
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  • 1,064
18 votes

Has any piston machine been used on a space mission?

Not sure that this is exactly what you seek, but the main pumps in the Space Shuttle hydraulic systems were "reciprocating piston variable displacement pumps". This type of pump was not ...
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17 votes

What is the largest number of humans in space at the same time and what vessels were they on when it happened?

Today (2021 Sept 16th) there are 14 people in orbit and above 100 km altitude (Karman Line): 7 in the ISS 4 in SpaceX Inspiration4 3 in the Chinese Tiangong space station
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17 votes
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Why did each F-1 engine have dual fuel feedlines?

This was done for load balancing purposes. The turbopump arrangement was as follows: the LOX pump at the top the fuel pump in the middle the turbine at the bottom The fuel was fed from two sides of ...
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17 votes

How well would Max Faget's April 1, 1969 design for the Space Shuttle have actually worked? What would have been the major problems?

Mission Requirements for a spaceplane that are affected by its aerodynamic shape Cross-range capability Gliding range perpendicular to orbital plane on reentry. Otherwise, you have to wait in orbit ...
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17 votes

What did Charlie Duke mean by "down on the ground"?

Looking over the mission transcript, the term 'the ground' always seems to refer to the various people speaking from Earth to the people up in space. 00 07 46 30 CC: "11, Houston. Those shaft ...
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  • 775
16 votes

How well would Max Faget's April 1, 1969 design for the Space Shuttle have actually worked? What would have been the major problems?

The straight wing concept was perfectly workable. According to The Space Shuttle Decision, Max Faget preferred the straight wing approach primarily because it would optimize performance in the final ...
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15 votes

First left-handed primate on the Moon? First in space?

You might want to look at How many astronauts are left handed? Buzz Aldrin, the second man on the Moon, is left handed. I think the first lefty in space was Walter Schirra (#9 to space) In the Apollo ...
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14 votes
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Mariner 9 computing equipment

Mariner 9 used magnetic core memory. It had the awesome amount of 512 words (quadrupled from the original design as requirements grew). The document never actually comes out and says so, but it's ...
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13 votes
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What does the ATOLL programming language look like?

The documentation for the Ground Operations Aerospace Language is much more available - search at ntrs.nasa.gov and a variety of reports come up. An ACM publication (which apparently is not a journal ...
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13 votes
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How relevant was Wernher von Braun really?

Management skills (the ability to herd cats) and technical skills (the ability to hunt like a cat) are very distinct skillsets. People who have both skillsets are rare. A wide range of technical ...
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  • 63.1k
13 votes

What are some of the obsolete technologies that space agencies used in day-to-day work during the 1960s?

Sending interdepartmental messages by pneumatic tube. Image Credit - NASA More info here. If an individual flight controller wanted a paper printout of one of his console displays, like a SMEK-...
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  • 806
12 votes

What Voyager spacecraft hardware performed transmitted data coding in such a complicated way? Did ground decoding use “a big monster filling a rack”?

Though what's in the Voyager remains to be seen, the Performance Study of Viterbi Decoding as Related to Space Communications1 gives a description of such a system implemented on Earth for the ground ...
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  • 46.1k
12 votes

Where did AS-206 go between 1967 and 1973?

From Stages to Saturn ch. 13: Developmental and technical problems created a delay in the anticipated launch date, which was finally rescheduled for the spring of 1973. Meanwhile the Saturn IB first ...
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  • 7,396
12 votes

What are some of the obsolete technologies that space agencies used in day-to-day work during the 1960s?

Here's a few. Mechanical calculators for better precision than a slide rule. Planimeter for determining moments of inertia. Used this at solid rocket manufacturer on military missile designs. Pen ...
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  • 1,989
11 votes

What is the largest number of humans in space at the same time and what vessels were they on when it happened?

The latest record is 19, from December 11, 2021. 10 on the ISS with two overlapping SpaceX crews, in orbit. 3 on the Chinese Tiangong Space Station, in orbit. 6 on Blue Origin's sub-orbital NS-19 ...
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11 votes
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What potential Shuttle partner did this blue-and-white flag indicate?

Most likely ESRO There is a 1973 document for ESRO detailing "File: ESRO-728 06/07/1973-27/07/1973 Draft Memorandum of Understanding between NASA and ESRO for a cooperative ...
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11 votes
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How "big" is a 2 megawatt preburner?

a tenth of the power of an SSME. 17.3MW is just the oxygen pump output, the hydrogen pump is by neccesity larger at an additional 53MW. For some more comparable gas-generator turbopump power outputs: ...
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