Sources cited

The original post

In 2010 Jason Roberts published a post on his blog Codus Operandi titled "How to Increase Your Luck Surface Area". The post's thesis:

"The amount of serendipity that will occur in your life, your Luck Surface Area, is directly proportional to the degree to which you do something you're passionate about combined with the total number of people to whom this is effectively communicated."

Jason Roberts, How to Increase Your Luck Surface Area (2010)

The formula

Roberts expresses the concept as:

L = D × T

where L is Luck, D is Doing and T is Telling. The analogy is geometric: just as the area of a rectangle is the product of its two sides, the "luck surface area" is the product of the two variables. If either one is zero, the product is zero regardless of the value of the other.

Paul Graham and How to Do Great Work

Paul Graham, in the essay How to Do Great Work (2023), discusses the role of luck and curiosity in careers without citing Roberts (see IBC episode 10).

The cameras of the Apollo missions

NASA had chosen Hasselblad as the official supplier for space photography as early as 1962. The choice was recommended by astronaut Walter Schirra, a Hasselblad enthusiast, who suggested the model to NASA; the first Hasselblad in orbit was a 500C modified by NASA, flown on the Mercury-Atlas 8 mission (October 3, 1962).

On the Apollo missions, the cameras' technical specifications were:

• Apollo 11: 3 × Hasselblad 500EL, two used on the lunar surface and one aboard the command module
• Hasselblad Data Camera (HDC): the camera dedicated to the lunar surface, fitted with a Zeiss Biogon 60mm f/5.6 lens and a 70mm magazine with thin-base Kodak film (150-200 images per magazine, depending on the film type)
• Silver finish for thermal stability in the range -65°C / +120°C

On NASA's instructions, at the end of each lunar mission the astronauts brought back only the film, leaving the camera bodies on the Moon. 12 Hasselblad bodies are still at the six Apollo landing sites today.

Technologically, the Apollo cameras were entirely analog, film-based. There were no electronic sensors of any kind.

The invention of the CMOS Active Pixel sensor

The CMOS Active Pixel image sensor (APS), the technology behind modern smartphone cameras, was invented at NASA's Jet Propulsion Laboratory (JPL) in 1993 by a team led by Eric Fossum and made up of Sunetra Mendis and Sabrina E. Kemeny.

The project was motivated by a specific mission: Cassini-Huygens to Saturn (launched 1997, arrived 2004). The candidate CCD cameras for Cassini were described as "as heavy as a mini-fridge": every extra gram on the probe meant more fuel needed and a more expensive mission. Fossum's team began the CMOS APS research to drastically reduce the size, weight and power consumption of onboard cameras while keeping the scientific image quality of CCDs.

The technical innovation of the APS sensor is integrating on a single chip:

• light detection (photodiodes)
• signal amplification
• signal readout

The result: a "camera-on-a-chip". Before Fossum's invention, a digital camera required a CCD sensor plus separate support chips, with much greater size and power consumption.

Eric Fossum was inducted into the National Inventors Hall of Fame in 2011 for this invention.

Cassini chose CCD, not CMOS

Even though the new technology had been developed precisely for Cassini, the mission team ultimately chose older but proven CCD cameras: the priority was reliability on a mission with 7 years of cruise plus 13 years of operations in the Saturn system.

CMOS APS went the way of the civilian market instead: in 1995 Fossum co-founded Photobit, licensing the technology from Caltech. Photobit was acquired by Micron Technology in 2001, and from there CMOS APS spread quickly into consumer products, all the way to smartphones.

From JPL to the smartphone

CMOS APS technology, developed for NASA probes, was transferred to civilian industry through the NASA Spinoff program and through Photobit.

Today CMOS sensors are used in more than 6 billion cameras produced every year. Applications include:

• every modern smartphone on the market
• webcams
• many consumer digital cameras
• medical imaging
• automotive vision systems

The Apollo → CMOS chain

The Apollo cameras were not the direct "parent" of smartphone cameras: Apollo used film, and CMOS was invented 25 years later. The link is JPL's continuity as a center for developing cameras optimized for spacecraft: NASA's investment in camera miniaturization, begun for Apollo and continued for Voyager, Mars Pathfinder and other probes, created the conditions for a physicist like Fossum to find at JPL the resources to develop CMOS APS in the early '90s.

Military origins (1973)

The GPS program was started by the US Department of Defense in 1973. That same year the program was named Navstar (NAVigation Satellite Timing And Ranging). The first 10 "Block I" prototype satellites were launched between 1978 and 1985. The full constellation of 24 operational satellites was reached in 1993.

The original goal was military: precise geolocation for air, sea and land navigation by the US armed forces.

KAL 007 and the opening to civilians (1983)

On September 1, 1983, the civilian flight Korean Air Lines 007, a Boeing 747 that had left New York for Seoul, was shot down by a Soviet interceptor after entering prohibited airspace over Sakhalin Island. 269 people died.

The subsequent analysis attributed the course deviation to navigation errors. In response, President Ronald Reagan announced in 1983 that GPS would be made available for civilian use once completed, initially to improve the safety of commercial aviation.

Initial civilian access, however, was deliberately degraded through a mechanism called Selective Availability (SA): civilian users were limited to an average accuracy of about 100 meters, while military receivers, authorized for the encrypted P(Y) code, had significantly better accuracy.

Selective Availability switched off (2000)

On May 1, 2000, President Bill Clinton ordered Selective Availability discontinued. From then on, civilian accuracy improved by about 10 times, reaching levels equivalent to military ones for most applications.

The decision was based on joint recommendations from the Departments of Defense, State, Transportation and Commerce and the CIA, in view of the global strategic value of precise GPS for transportation, science and commerce.

How it works: atomic clocks

Every GPS satellite carries atomic clocks (cesium or rubidium) with nanosecond precision. The satellite continuously transmits its precise position and the exact timestamp of the transmission.

A GPS receiver on the ground receives the signal from at least 4 satellites, calculates the signal's travel time from each one (speed of light × time difference), and from these 4 distances trilaterates its three-dimensional position plus the time offset.

An error of 1 microsecond in synchronization translates into a position error of about 300 meters (since light travels ~300 m/µs).

Einstein's corrections (38 µs/day)

The atomic clocks on GPS satellites are subject to two relativistic effects of opposite sign:

• Special relativity (effect of the orbital speed, ~14,000 km/h): the clocks run slow by about 7 microseconds per day compared with clocks on Earth.
• General relativity (effect of the weaker gravity at 20,200 km altitude): the clocks run fast by about 45 microseconds per day compared with clocks on Earth.

Net effect: GPS clocks in orbit run faster than clocks on the ground by about 38 microseconds per day.

Without correction, the accumulated error would produce a position offset of about 10 km per day, and the system would become unusable within hours. The correction has been built into the system since launch: the onboard clocks are set to a deliberately slower frequency before launch, so that in orbit they run at the correct "Earth" rate.

GPS is therefore a continuous operational demonstration of Einstein's theory of relativity: without it, it wouldn't work.

Economic value (RTI/NIST, $1.4 trillion)

A study commissioned by NIST (National Institute of Standards and Technology) from RTI International, published in 2019, estimated the cumulative economic value of GPS to the US private sector since 1983.

Main findings:

• $1.4 trillion in cumulative economic value generated across 10 key industries from 1983 to 2017
• about 90% of this value accrued after 2010, reflecting the spread of GPS into smartphones and across transportation, precision agriculture and telecommunications
• the 10 industries measured include: agriculture, electricity, finance, location-based services, mining, maritime, oil & gas, surveying, telecommunications, telematics
• a GPS outage would have an estimated economic impact of $1 billion per day; a 30-day outage during planting season up to $45 billion

Mapping the ocean floor

The Seabed 2030 project, launched in 2017 by the Nippon Foundation in collaboration with GEBCO (General Bathymetric Chart of the Oceans) under the auspices of the International Hydrographic Organization (IHO), has the stated goal of completely mapping the world's ocean floor by 2030.

When the project was launched, in 2017, only 6% of the ocean floor had been mapped to modern standards.

In April 2026, the official update presented to the IHO Assembly in Monaco by Mitsuyuki Unno (executive director of the Nippon Foundation) reported:

• 28.7% of the world's ocean floor mapped
• about 104 million km² of total area covered
• about 5 million km² added in the past year

Mapping Mars

NASA's Mars Reconnaissance Orbiter (MRO) has been orbiting Mars since 2006. Surface coverage differs by resolution:

• Context Camera (CTX): passed 99% of the Martian surface by 2017 (over 99% mapped at ~6 m/pixel)
• HiRISE (High Resolution Imaging Science Experiment): covers about 2-3% of the Martian surface at much higher resolution (~25 cm/pixel)

The difference comes from the design: CTX aims for global coverage at medium resolution; HiRISE aims for maximum detail over limited areas.

Mapping the Moon

NASA's Lunar Reconnaissance Orbiter (LRO) has been orbiting the Moon since 2009. Its mapping coverage:

• 98.2% of the lunar surface mapped at 100 m/pixel resolution (excluding the permanently shadowed poles)
• 0.5 m/pixel resolution at the Apollo landing sites

Why mapping the ocean is slower

The difference in coverage between the oceans and celestial bodies doesn't depend on money but on the physics of the medium.

Seawater absorbs almost all electromagnetic radiation (radio waves, infrared, visible light, X-rays), with an efficiency that depends on the frequency. Radio waves (radar) penetrate seawater about 1,000 times less than acoustic waves (sonar). This makes it impossible to map the ocean floor from space with a radar satellite, as was done for Venus instead (Magellan's radar, 1990-1994).

The only practical instrument is sonar: acoustic waves emitted by a submerged transducer. The operational consequence: to map the seafloor you need a ship or an AUV (Autonomous Underwater Vehicle) to cross the area with the transducer in the water. While MRO's orbits cover all of Mars in months, a ship has to cover every km² of the seafloor one by one.

Newton's thought experiment

Isaac Newton conceived the cannon experiment as an illustration of the link between gravity and orbital motion. The concept was set out in words in Book III of the Philosophiæ Naturalis Principia Mathematica (1687). The famous cannon figure, with the diagram that later became iconic, was published posthumously in 1728 in De Mundi Systemate (On the System of the World).

The experiment imagines a cannon placed on top of a very high mountain, firing a projectile horizontally. Varying the initial speed:

• at low speed, the projectile follows a short parabolic path and quickly falls to the ground
• at higher speed, the arc gets longer
• at one precise speed, the falling arc matches the curvature of the Earth: the projectile falls without ever touching the ground, in a circular orbit

Circular orbit speed

For a low circular orbit around the Earth (low Earth orbit), the speed needed is about 7.9 km/s.

The exact speed depends on altitude: the higher the orbit, the lower the speed required. For the International Space Station at about 400 km altitude, the orbital speed is ~7.67 km/s (27,600 km/h).

At this speed, the ISS completes one orbit around the Earth in ~93 minutes, about 15-16 orbits a day.

The geometry of "5 m every 8 km"

An intuitive way to put orbital mechanics: because of its curvature, the Earth's surface drops by about 5 meters every 8 kilometers of horizontal distance.

An object in low orbit moves horizontally fast enough that, in the time it takes to fall 5 meters under gravity, it has already traveled 8 km horizontally, a distance over which the Earth has curved away by 5 m. So the projectile keeps "missing the ground": it is a continuous fall with no impact.

Mathematically, for an Earth radius R = 6,378 km, the drop over 8 km is about 8² / (2 × 6,378) ≈ 0.005 km = 5 m.

What "falling forever" means

In orbit, the ISS is in continuous free fall. Astronauts don't float because "there's no gravity": on the contrary, gravity at 400 km altitude is still about 90% of what it is at the Earth's surface. They float because they are falling together with the station at the same speed, a state called microgravity or "apparent zero-g".

Keeping the orbit

The ISS orbit isn't passively stable: the residual atmosphere at 400 km exerts a weak aerodynamic drag that slowly lowers the altitude. Periodically the station's thrusters (or those of a docked capsule) perform a reboost to bring the ISS back to its nominal altitude.

Initial adaptation (1-4 days)

In their first days in orbit, astronauts experience spatial disorientation and space motion sickness (Space Adaptation Syndrome). The acute symptoms (nausea, dizziness, an altered sense of "up" and "down") gradually fade over a period of 1 hour to 4 days (Frontiers in Neural Circuits, 2021).

After this initial phase, the astronaut can make voluntary head movements without significant discomfort.

Sensory reweighting

The vestibular system (inner ear) uses gravity as its reference for orientation. In microgravity, this input becomes unreliable.

The nervous system responds with a process called sensory reweighting: it updates its internal model and gives more weight to other sensory sources, visual and somatosensory information (proprioception, touch), reducing the weight of the ambiguous vestibular signal.

This sensory rebalancing can develop over two weeks of microgravity (Cerebral Cortex, 2022).

SANS: Spaceflight-Associated Neuro-Ocular Syndrome

SANS is a neuro-ocular syndrome formally described in 2011 in a cohort of 7 astronauts.

Clinical features:

• optic disc edema
• swelling of the retinal nerve fiber layer (RNFL)
• flattening of the back of the eyeball (globe flattening)
• choroidal and retinal folds
• hyperopic refractive shift (≥+0.75 D)

The most common symptom is a progressive reduction in near visual acuity, which can appear after as little as 3 weeks of flight.

Estimated prevalence: about 70% of astronauts on long ISS missions show some degree of retinal swelling.

Proposed cause: the chronic headward shift of blood and cerebrospinal fluid in the absence of gravity.

To date no cases of permanent vision loss have been reported, but some clinical signs of SANS (refractive changes, choroidal and retinal folds, posterior flattening) persist even after return.

Structural brain changes

Pre- and post-flight MRI studies of long-mission astronauts show:

• a 17-24% increase in the volume of the lateral ventricles after 6 months in orbit: left lateral ventricle +17±12%, right +24±6% (Roberts et al., PNAS)
• an annual rate of ventricular expansion 3 times higher than normal aging
• partial recovery after return: after 6-7 months on Earth, the ventricles had returned only 55-64% of the way to their pre-flight size

Intervals of less than 3 years between missions are associated with incomplete recovery of the ventricular changes.

NASA Twins Study (Scott Kelly)

The NASA Twins Study compared astronaut Scott Kelly (340 days on the ISS, 2015-2016) with his identical twin brother Mark Kelly, who stayed on Earth.

Main findings:

• Gene expression: 93% of Scott's genes returned to normal levels after his return. The remaining 7% showed persistent changes in genes related to the immune system, DNA repair, bone formation, hypoxia and hypercapnia.
• In-flight cognition: Scott's cognitive performance (attention, spatial orientation, emotion recognition) was unchanged compared with Mark's during his time in orbit.
• Post-flight cognition: after his return, Scott showed a decline in speed and accuracy on cognitive tests, attributed to readapting to Earth's gravity.

Post-flight recovery

After returning to Earth, the astronaut has to readapt the vestibular system to gravity, sensory reweighting in reverse. Balance problems (postflight vestibular dysfunction) resolve over days to weeks.

Some structural changes (ventricular volume, some signs of SANS, a fraction of gene expression) remain measurable beyond 6-12 months after flight.

What AMS-02 is

The Alpha Magnetic Spectrometer-02 (AMS-02) is a particle detector designed to measure cosmic rays from space, outside the Earth's atmosphere.

Main features:

• Cost: about $2 billion
• Mass: about 8,500 kg (8.5 tonnes), the largest single payload on the ISS
• Collaboration: 500 scientists, 56 groups, 16 countries
• Scientific goals:
• measure the composition and energy of cosmic rays
• search for evidence of dark matter
• search for evidence of primordial antimatter (antihelium in particular)
• measure the fraction of positrons and antiprotons in primary cosmic rays

Unlike particle physics experiments on Earth (such as those at CERN), which produce particles in colliders, AMS-02 directly observes the high-energy particles arriving from space. The Earth's atmosphere filters and alters these particles: to measure them in their original composition you need a detector outside the atmosphere.

Mission duration: originally planned for 3 years, it has been extended several times and is still operating.

Samuel Ting, the principal investigator

The principal investigator of AMS-02 is Samuel C.C. Ting, a particle physicist at the Massachusetts Institute of Technology (MIT).

Ting received the 1976 Nobel Prize in Physics, shared with Burton Richter, for the discovery of the J/ψ meson, a subatomic particle discovered in 1974 in experiments at Brookhaven National Laboratory (Ting) and at the same time at SLAC (Richter). The discovery of the J/ψ was the experimental proof of the existence of the charm quark.

Ting proposed, designed and led the construction of AMS-02 over more than 15 years of development, coordinating the international collaboration.

Installation on the ISS (STS-134, 2011)

AMS-02 was launched on May 16, 2011 aboard the Space Shuttle Endeavour, mission STS-134, Endeavour's last flight (the Space Shuttle program as a whole ended with Atlantis's STS-135 on July 8, 2011).

Installation on the ISS's external structure, on the S3 truss, was completed on May 19, 2011.

The 4 repair EVAs (2019-2020)

In 2019, after 8 years of operations, AMS-02 had a faulty pump in its cooling system (Tracker Thermal Pump System, TTPS), which threatened the continuity of its observations. The replacement required a series of especially complex EVAs for two reasons:

• AMS-02 had not been designed to be repaired in orbit (unlike, for example, the Hubble telescope)
• its position on top of the station's S3 truss made access difficult

NASA and ESA planned 4 spacewalks carried out by NASA astronaut Drew Morgan and ESA astronaut Luca Parmitano:

EVA	Date	Main task
1	November 15, 2019	Removal of the debris shield and carbon-fiber insulation; installation of temporary handrails
2	November 22, 2019	Cutting and preparing the coolant lines for the later splicing
3	December 2, 2019	Installation of the new UTTPS cooling system (Upgraded Tracker Thermal Pump System); connection of all 8 coolant lines
4	January 25, 2020	MLI (Multi-Layer Insulation) thermal covers; installation of a jumper for a faulty coolant line found during testing

NASA described the 4 EVAs as the most complex spacewalks since the last Hubble Space Telescope servicing mission in 2009 (STS-125).