The digital ranging system that measured the distance to the Apollo spacecraft
The basic idea was to send a radio signal to the spacecraft and determine how long it takes to return. Since the signal traveled at the speed of light, the time delay gives the distance. The main problem is that due to the extreme distance to the spacecraft, a radar-like return pulse would be too weak. The ranging system solved this in two ways. First, a complex transponder on the spacecraft sent back an amplified signal. Second, instead of sending a pulse, the system transmitted a long pseudorandom bit sequence. By correlating this sequence over multiple seconds, a weak signal could be extracted from the noise.
In this blog post I explain this surprisingly-complex ranging system. Generating and correlating pseudorandom sequences was difficult with the transistor circuitry of the 1960s. The ranging codes had to be integrated with Apollo’s “Unified S-Band” communication system, which used high-frequency microwave signals. Onboard the spacecraft, a special frequency-multiplying transponder supported Doppler speed measurements. Finally, communicating with the spacecraft required a complex network of ground stations spanning the globe.
An Orbit Map of the Solar System
This map shows the orbits of more than 18000 asteroids in the solar system. This includes everything we know of that’s over 10km in diameter - about 10000 asteroids - as well as 8000 randomized objects of unknown size. Each asteroid is shown at its position on New Years’ Eve 1999, colored by type of asteroid.
Hasselblad, Kodak, & Apollo 11
A probably not entirely wrong history of cameras developed for the moon.
In 1927, a Baltimore man was on a mission to blast off to Venus. Nearly a century later, a documentary crew is on its own mission to find the rocket built for that journey.
Some great illustrations, too.
'Soviet Space Graphics' takes you inside the cosmic visions of the USSR
One new book transports readers back to the early days of Soviet spaceflight with an unbelievable collection of stunning, colorful and nostalgic images. “Soviet Space Graphics: Cosmic Visions from the USSR,” (Phaidon, 2020), released April 1, is a masterful compendium of images showcasing space design ideas from the then Soviet Union from the 1920s through the 1980s. It highlights the beauty of early space design in imaginative, colorful artworks.
That time a monkey flew to the edge of space
So when NASA’s young engineers at Langley Research Center in Virginia began testing their new Mercury capsule in flight, they wanted to see whether the accelerations experienced during the abort of a Mercury flight shortly after launch were survivable. Enter Sam, an eight-pound rhesus monkey.
The July Galileo Outage: What happened and why
This post is an excerpt of a far longer post on Galileo, its structures and the cause of the outage. Here we’ll only focus on the outage - the potential underlying reasons behind it are described in the full article.
Since the week-long outage in July I’ve been fascinated by Galileo and, together with a wonderful crew of developers, experts and receiver operators, have learned so much about what I now know are called ‘Global Navigation Satellite Systems’ or GNSS. This has lead to the galmon.eu project, which monitors the health and vital statistics of GPS, Galileo, BeiDou and GLONASS. More about the project can be read in the full article.
I totally missed the fact that there was an outage, but some interesting commentary.
Reach for the Moon: Four Lives, the Space Race and a Chaotic Decade
Alan Contessa (left) worked on the lunar module. Frances ‘Poppy’ Northcutt was a ‘computress’ for TRW Systems. Morgan Watson was a NASA engineer, John Wolfram (right) a Navy SEAL.
Over the next eight years, success depended upon people like Morgan Watson, a black man from the segregated schoolhouses of rural Louisiana; Frances “Poppy” Northcutt, a high-school valedictorian and onetime beauty contestant from the Texas oil patch; Alan Contessa, a working-class kid from New York City’s outer boroughs; and John Wolfram, a rebel with a patriotic streak from the Wisconsin countryside.
The Atlas of Moons
Our solar system collectively hosts nearly 200 known moons, some of which are vibrant worlds in their own right. Take a tour of the major moons in our celestial menagerie, including those that are among the most mystifying—or scientifically intriguing—places in our local neighborhood.
Pretty heavy web page.
Why Nasa’s next Moon mission can’t be an Apollo retread
There is a familiar question asked of politicians, entrepreneurs and innovators: if you were to do it all again, what would you do differently?
At Nasa headquarters, they’re fielding almost the opposite inquiry. Why don’t you just do it the same? If you managed to put Neil Armstrong and Buzz Aldrin on the Moon five decades ago, why is it so hard to do it now?
Mary Sherman Morgan, Rocket Fuel Mixologist
The US had twice tried to launch Navy-designed Vanguard rockets, and both were spectacular failures. It was time to use their ace in the hole: the Redstone rocket, a direct descendant of the V-2s designed during WWII. The only problem was the propellant. It would never get the payload into orbit as-is.
The US Army awarded a contract to North American Aviation (NAA) to find a propellant that would do the job. But there was a catch: it was too late to make any changes to the engine’s design, so they had to work with big limitations. Oh, and the Army needed it two days before yesterday.
The Army sent a Colonel to NAA to deliver the contract, and to personally insist that they put their very best man on the job. And they did. What the Army didn’t count on was that NAA’s best man was actually a woman with no college degree.
‘Houston, we have a problem’: The amazing history of the iconic Apollo 13 misquote
Swigert: “Okay, Houston, we’ve had a problem here.”
Mission control: “This is Houston. Say again, please.”
Lovell: “Uh, Houston, we’ve had a problem.”
A Huge Collection of Apollo 11 Press Kits
When Apollo 11 landed two men on the Moon and returned them safely to Earth, thousands of people at NASA were joined in the effort by dozens of companies that did everything from building the spacecraft to providing the cameras for the mission. Each of those companies was understandably proud of their involvement and wanted to use the mission to drum up interest in their products and services. Marketing strategist David Meerman Scott has been collecting the press kits produced by the Apollo contractors and has made them available online for free download in PDF format.
Main link: https://www.apollopresskits.com
Inside the Apollo Guidance Computer's core memory
The Apollo Guidance Computer (AGC) provided guidance, navigation and control onboard the Apollo flights to the Moon. This historic computer was one of the first to use integrated circuits, containing just two types of ICs: a 3-input NOR gate for the logic circuitry and a sense amplifier IC for the memory. It also used numerous analog circuits built from discrete components using unusual cordwood construction.
Also core rope: http://www.righto.com/2019/07/software-woven-into-wire-core-rope-and.html
Erasable core memory and core rope both used magnetic cores, small magnetizable rings. But while erasable core memory used one core for each bit, core rope stored an incredible 192 bits per core, achieving much higher density.2 The trick was to put many wires through each core (as shown above), hardwiring the data: a 1 bit was stored by threading a wire through a core, while the wire bypassed the core for a 0 bit. Thus, once a core rope was carefully manufactured, using a half-mile of wire, data was permanently stored in the core rope.
Also, Bitcoin: http://www.righto.com/2019/07/bitcoin-mining-on-apollo-guidance.html
Also, NOR gates: http://www.righto.com/2019/09/a-computer-built-from-nor-gates-inside.html
This historic computer was one of the first to use integrated circuits and its CPU was built entirely from NOR gates. In this blog post, I describe the architecture and circuitry of the CPU.
The 26,000-Year Astronomical Monument Hidden in Plain Sight
On the western flank of the Hoover Dam stands a little-understood monument, commissioned by the US Bureau of Reclamation when construction of the dam began in 01931. The most noticeable parts of this corner of the dam, now known as Monument Plaza, are the massive winged bronze sculptures and central flagpole which are often photographed by visitors. The most amazing feature of this plaza, however, is under their feet as they take those pictures.
The plaza’s terrazzo floor is actually a celestial map that marks the time of the dam’s creation based on the 25,772-year axial precession of the earth.
Why have humans never found aliens?
Dr Tarter reckoned that decades of searching had amounted to the equivalent of dipping a drinking glass into Earth’s oceans at random to see if it contained a fish. Dr Wright and his colleagues built on Dr Tarter’s work to come up with a model that tries to estimate the amount of searching that alien-hunters have managed so far. They considered nine variables, including how distant any putative aliens are likely to be, the sensitivity of telescopes, how big a portion of the electromagnetic spectrum they are able to scan and the time spent doing so. Once the numbers had been crunched, the researchers reckoned humanity has done slightly better than Dr Tarter suggested. Rather than dipping a drinking glass into the ocean, they say, astronomers have dunked a bathtub.
Virgin Galactic's Rocket Man
The ace pilot risking his life to fulfill Richard Branson’s billion-dollar quest to make commercial space travel a reality.
Stucky had piloted SpaceShipTwo on two dozen previous test flights, including three of the four times that it had fired its rocket booster, which was necessary to propel it into space. On October 31, 2014, he watched the fourth such flight from mission control; it crashed in the desert, killing his best friend. On this morning, Stucky would be piloting the fifth rocket-powered flight, on a new iteration of the spaceship. A successful test would restore the program’s lustre.
And a little note at the end, unrelated to the crash:
As it turned out, there had been a glitch in the gyros’ software; the manufacturer had issued a patch, but hadn’t indicated that it fixed a major problem, so Virgin Galactic hadn’t installed it.
McMoon: How the Earliest Images of the Moon Were so Much Better than we Realised
Fifty years ago, 5 unmanned lunar orbiters circled the moon, taking extremely high resolution photos of the surface. They were trying to find the perfect landing site for the Apollo missions. They would be good enough to blow up to 40 x 54ft images that the astronauts would walk across looking for the great spot. After their use, the images were locked away from the public, as at the time they would have revealed the superior technology of the USA’s spy satellite cameras, which the orbiters cameras were designed from. Instead the images from that time were grainy and low resolution, made to be so by NASA.
Boeing and SpaceX Are Racing to Bring Astronauts, Then Tourists, to Space
Now Boeing Co. and Elon Musk’s Space Exploration Technologies Corp. are preparing to ferry Americans to space for the first time since the Space Shuttle program went dark in 2011. If all goes well during a flurry of testing over the coming months, Boeing’s CST-100 Starliner will carry two astronauts to orbit in November, followed by SpaceX’s Crew Dragon in December. Those first manned flights by these companies would usher in the first-ever commercial taxi service to earth orbit in 2019, followed by a battle to tempt high-spending tourists to take a trip into space.
Andy Weir on the Economics of Sci-Fi and Space
In addition to these important questions of lunar economics, Andy and Tyler talk about the technophobic trend in science fiction, private space efforts, seasteading, cryptocurrencies, the value of a human life, the outdated Outer Space Treaty, stories based on rebellion vs. cooperation, Heinlein, Asimov, Weir’s favorite episode of Star Trek, and the formula for finding someone else when stranded on a lonely planet.