OrbitalHub

In mid-August, on a concrete ramp at an undisclosed airport in Oklahoma, a freshly painted Boeing 737-700 sat in red, white, and blue. The NASA meatball was on the tail, the registration N837NA on the rear fuselage, and the words reduced gravity research aircraft across the cabin. NASA released the frames on 13 August 2026 (NASA, August 2026).

Behind the new paint is a stranger story. This airframe was delivered to a private operator in 2013 as N712JM, a Boeing 737-73W. By 2020, plane spotters noticed it sitting at Colorado Springs in a green protective coating, bristling with sensors and wiring runs no commercial jet had any business carrying. Aviation journalists at The War Zone traced the registered mailing address on its airworthiness documents to the same building that houses the U.S. Air Force's Rapid Capabilities Office, the secretive acquisition outfit that fields programs like the B-21 Raider. The Air Force confirmed to The War Zone that N712JM flew for a classified program that has since ended, and NASA acknowledged in contracting documents that the agency itself did not have the need-to-know (The Aviationist, 17 August 2026; The War Zone, 2024).

NASA Armstrong Flight Research Center took ownership in June 2026. The new "NASA 837" carries the registration that once belonged to the agency's NF-15B test jet, retired in 2009 after 36 years of flight-control research. The 737 inherits the number; the secrets stay behind.

Landing on the Moon is not like floating in orbit. The Moon pulls at roughly 1.62 m/s², about one-sixth of Earth's 9.81 m/s², and a pressurized suit under that load behaves in ways pure weightlessness cannot reproduce. A suit that weighs as much as the person inside it changes the biomechanics of walking, picking up rocks, climbing ladders, and getting up after a fall. Ground labs cannot simulate those effects without removing gravity.

NASA's answer for decades has been parabolic flight. A maneuvering aircraft traces the arc of a free-falling object, so for a brief window everything inside the cabin, including the aircraft, falls together. The standard maneuver gives about 20 seconds of microgravity per parabola, with 15 to 30 parabolas stacked into one flight (NASA, "Parabolic Flight," 2026). Roughly two-thirds of first-time passengers get sick, which is how the aircraft picked up its unofficial name.

Microgravity is the wrong flavor of reduced gravity for Artemis. To produce Moon-like 1/6 g, the pilot cannot just unload the controls and coast. The trajectory must be flown with the airplane carrying more lift and slightly more thrust than it would in a true free fall, so its downward acceleration in the inertial frame is about 8.2 m/s², the difference between Earth's 9.81 and the Moon's 1.62. Mars at 0.38 g needs a smaller lift offset. Each profile is a separate skill and a separate test campaign for whatever the experimenters strap to the cabin floor.

NASA has been without a dedicated government parabolic jet since the agency wound down the Reduced Gravity Research Program in July 2014, after its McDonnell Douglas C-9B Skytrain II (N932NA, ex-KLM) developed unsolvable airworthiness issues. The agency now charters flights from Zero Gravity Corporation's Boeing 727-200, G-FORCE ONE, and from Novespace's Airbus A310 Zero-G in Bordeaux-Mérignac. Both can simulate lunar and Martian gravity, but neither belongs to NASA, and neither is configured for the suit qualification Artemis is asking for (Wikipedia, "Reduced-gravity aircraft," 2026).

On 1 June 2026, NASA awarded Denmar Technical Services of Nevada an $8.4 million firm-fixed-price contract to modify the 737-700 for lunar-gravity parabolic operations. The contract runs through 1 February 2027, after which the aircraft will be owned by NASA Armstrong but flown out of NASA Johnson in Houston, with Armstrong retaining oversight (NASA, 1 June 2026).

The aircraft's primary job is astronaut lunar suit qualification. Each Artemis crew will run parabolas inside the pressurized suit, working through the tasks they expect on the surface: kneeling to deploy a sample scoop, picking up a rock, recovering from a stumble, climbing into a lander hatch. NASA has historically used neutral buoyancy, the large pools where suited astronauts practice procedures underwater, for most of this training, and the agency's new Langley partial-gravity simulator will handle suspension-based work. The 737 adds a third leg: short bursts of true free-fall at lunar gravity, in an aircraft moving fast enough to give the suits a realistic test of inertia.

The 737 will also serve as a flying testbed for autonomy, sensors, and digital flight-control research under Armstrong's traditional portfolio (NASA, 13 August 2026).

A parabolic trajectory is, in the inertial frame, what Newton predicted for any object under gravity alone: a constant downward acceleration of g, with the horizontal component unchanging. The aircraft pulls up at about 45°, trading airspeed for altitude. The pilot throttles back to idle and pushes the nose over. From that point, the plane falls along the same arc a dropped stone would, and so does everything loose inside it. From the cabin's frame of reference, gravity simply vanishes. The reduced-g phase ends when the descent angle reaches roughly 30° below horizontal, where the pilot must pull out.

The 20-second budget is set by how steeply the plane can dive without exceeding airframe limits or the FAA's airspeed envelope. A 737 enters the maneuver around 7,600 m at roughly 450 km/h. The velocity vector rotates from 45° up through horizontal to 30° below, a swing of 75°, with no vertical speed at the top and acceleration equal to g along the way. That arc, plus the climb-out and recovery, gives 20 to 25 seconds. Each parabola is bookended by a 1.8 g pull-up and a 1.8 g pull-out, so a passenger's g-load in one cycle runs 1.8 g → ~0 g → 1.8 g (NASA, "Parabolic Flight," 2026).

To produce lunar gravity rather than zero, the trajectory follows a shallower arc in which the cabin accelerates downward more slowly than a true free-falling object would. The pilot adds enough lift and a small, steady nose-down command so the airplane traces an arc that would correspond to falling toward a body with a stronger pull than the Moon. The residual force on cabin occupants is the difference between Earth's gravity and the airplane's actual downward acceleration: 9.81 − 8.19 ≈ 1.62 m/s², or about 0.165 g. Mars is easier at 3.71 m/s².

The aircraft modifications are mostly about padding and instrumentation, not propulsion. A 737 already has the wing loading, thrust margin, and fuel capacity to absorb a parabolic stack. The hard engineering is in protecting the cabin from the 1.8 g bookends (suited astronauts get crushed into their seats for the first and last 30 seconds of every parabola) and in mounting cameras, accelerometers, and umbilicals so test subjects can be observed without falling on top of each other in 0.165 g.

The new 737 is one piece of a much larger validation program. The Artemis suit, the Human Landing System, the Gateway space station, and the rovers all eventually need real partial-gravity testing before they fly. Neutral buoyancy will keep handling long, procedure-driven rehearsals. The Langley gantry will handle suspension work. The 737 supplies what neither can: short, repeated, true free-fall at the right fraction of Earth gravity, even if only twenty seconds at a time.

It is also, quietly, the agency's first government-owned research aircraft with a classified past NASA still cannot fully explain. The engineers at Armstrong and Johnson get the airplane and the schedule. The historians will keep digging.

Abstract

The blogpost explores relativistic effects on proof-of-work based cryptocurrency protocols. Cryptocurrencies are here to stay and it is quite plausible that future human colonists spread across the solar system and beyond will use a decentralized cryptocurrency as opposed to a fiat currency issued by a central authority. The low transaction fees, the ubiquitous access, not being bound by exchange rates or interest rates, not being controlled by financial institutions who are serving foreign interests -- these are some of the advantages cryptocurrencies will enjoy in the thriving exo-economy.

Motivation

At present, on a cryptocurrency network, the information exchanged by the nodes in the network reaches each node almost instantaneously. The speed at which the TCP/IP packets travel on the network and the fact that the Internet spans only the Earth and the LEO makes this possible. However, once the region the network is spread across will reach certain boundaries, the network size would have negative impact on the network: increasing communication failures due to network delays, more frequent and longer blockchain forks as part of the proof-of-work protocol, network segregation into local sub-networks (let us call them topological forks), just to name a few.

Nullius in verba... as they say. Let's go deeper into details and figure out a feasible solution for a truly interplanetary cryptocurrency.

Cryptocurrency 101

You can think of a cryptocurrency as a digital money ecosystem. Plain and simple. A collection of technologies are part of this ecosystem, all of them the result of years of research in the cryptography and distributed systems fields: a decentralized network of computers, a public transaction ledger -- also known as a blockchain, a protocol that consists of a set of rules for transaction validation, a decentralized consensus mechanism. [ANTO]

A decentralized network of computers ensures the resilience of the network. We can think of both computing power and data storage capabilities. As the computing power is distributed across the network, any disruption can be successfully handled by the network. Transaction data resides on all nodes of the network. This implies that even physical damage done to network nodes will not take out the network.

The blockchain is a public distributed ledger which stores all transactions handled by the network. As the name suggests, the blockchain is a list of data blocks. Each of these blocks contains a set of transactions, as many as can fit in the block, given the maximum size of the block (a characteristic of the network). Transactions contain sender and receiver info, and the amount/asset that is changing ownership, and they are broadcasted and added to blocks by network nodes. Blocks are linked to the previous block in the chain by a cryptographic hash (the hash of the previous block becomes part of the current block). This backward link leads all the way to the first block in the chain, the Genesis block. Each cryptocurrency blockchain has one. The cryptographic hashes have an important role in protecting the blockchain from tampering attempts.

The transaction validation rules enforced by the nodes in the network ensure that the content of each block in the blockchain is valid. By far, the most frequent form of fraud is double spending. The validation process makes sure that the inputs on the transactions exist and that they have not been already spent. The transactions marked as invalid are rejected by the network and do not make it on the blockchain.

The consensus mechanism is designed so that all the nodes in the network can agree on the set of transactions to be included in the current block. It shifts the authority and the credibility required by a central clearing house to a network of nodes. Important to mention here that, inherently, the nodes do not trust each other, and they do not have to because the trust is enforced by the consensus mechanism itself.

The Proof-of-Work

We mentioned above that one of the key innovations that make cryptocurrencies possible is the decentralized consensus mechanism. Currently, the de facto consensus mechanism is the proof-of-work.

The proof-of-work consensus mechanism was proposed by Satoshi Nakamoto in 2008 [NAKA]. In general, a proof-of-work is a piece of data that requires costly and time consuming computational effort, but it is very easy to verify. A very good analogy is one of your semester projects in college... it takes you a whole semester to finalize it, but it takes very little time and effort for your supervisor to evaluate and grade it. Similarly, proof-of-work is used by cryptocurrencies for block generation. For the network to accept the block, nodes must complete a proof-of-work which also guarantees the integrity of the transactions included in the block. The difficulty of the proof-of-work is adjusted by the network so that a new block can be generated every fixed time interval. This fixed time interval is characteristic to every cryptocurrency. Most notably, for Bitcoin this time interval is set to 10 minutes.

Satoshi Nakamoto's solution, emobodied by the proof-of-work algorithm above, achieves consensus on the network without a central trusted authority (hence the name decentralized consensus mechanism).

Enter the Ansible

For the astute reader, it is quite obvious at this point that communication delays between the network nodes have a direct effect on the protocol described above. An important assumption made when the protocol was designed is that these delays are small, and this is why they can be handled by the network when the nodes choose to follow and validate the blocks on the longest blockchain fork. Also, this is the reason why all the nodes in the network can have a say in the network consensus. They all can find a solution for the current block, and they all can be rewarded when they find the solution. The communication delays witnessed by the peripheral nodes will cripple their ability to find solutions and these nodes will not be incentivized to remain in the network. Hence, the segregation of the network effect mentioned earlier.

Unfortunately, given the current technological level of our civilization, we do not have at our disposal a technology that allows us to communicate fast and reliable over the large expanse of space. It would take a hell of a wait time to proces a payment made by a mining corporation in the TRAPPIST-1 system, 12 parsecs within the constellation of Aquarius, to a planetary engineering corporation located in the Sol system... twice 39 years plus the block confirmation time.

Fortunately, the Sci-Fi literature already offers a solution for our problem. For those of you, Sci-Fi nerds like myself, that have already read Rocannon's World [LEGU] and Ender's Game [CARD], the Ansible device must sound very familiar. The ansible is a fictional device capable of faster-than-light communication. To word this differently, an operator of such device can send and receive messages to and from another device over any distance with no delay.

Hence, even if only in the realm of science fiction, we will be able to devise a solution for the problem that the future cryptocurrency enthusiasts, living in the outer space colonies, will eventually face.

The Special Relativity Theorem

Before elaborating more on a required upgrade of the network protocol, we have to discuss the special relativity theorem and its implications on how time and distance are perceived in reference systems.

Albert Einstein was awarded the Nobel Prize in Physics in 1921. He received it for his contributions to the understanding of the photoelectric effect, after publishing a paper on it in 1905. At that point his contributions to the understanding of gravity through his theory of relativity were well known, but the new perspective on gravity offered by Einstein's theory was so controversial that the Nobel Prize Committee members chose to protect their reputation. They decided that it was appropriate to award Einstein the Nobel Prize for "his services to theoretical Physics, and especially for his discovery of the law of the photoelectric effect."

During his research Einstein attempted to reconcile the principle of relativity with the principle of the constancy of the velocity of light. This attempt led Einstein to the discovery of the special relativity theorem. Einstein's Gedankenexperiment (thought experiment) with a test subject travelling by train is very well known in the scientific community. If our human subject is walking towards the front of the train with velocity w with respect to the train, and the train is moving with velocity v with respect to the embankment, then an observer on the embankment will measure as W = v + w the velocity of our subject on the train. If instead of our traveller, we consider a beam of light propagating with velocity c, the velocity measured by the observer on the embarkment would be v + c. However, this violates the principle that the velocity of light is constant in any inertial reference system and equal with c. Einstein found a solution for this problem and thus resolved the incompatibility.

One direct consequence of the special relativity theorem is the Lorentz transformation.

Before the relativity theorem, time in physics had an absolute significance, independent of the state of motion of the reference system. However, every inertial reference system has its own particular time. We always have to be told which inertial reference system the statement of time refers to. If you look at your watch, the time you read is the time as measured in the Earth inertial reference system. By the way, the Earth circles the Sun on an almost circular orbit, which means that any body maintaining a constant position in the Earth reference system should experience some centripetal force. However, this centripetal component is negligible compared to the gravitational pull of the Earth. Hence, engineers use this aproximation when calculating satellite orbits.

Back to our original trail of thoughts... the axiom that lays the foundation for the Lorentz transformation states that every ray of light possesses the velocity of transmission c relative to any inertial reference system. That is the velocity of transmission in vacuo (in a vacuum).

If following Einstein's thought experiments [EINS], the above-mentioned axiom leads to a set of four equations that explain the relation between dimensional and temporal coordinates in two inertial reference systems:

  x' = (x - vt)/sqr(1 - v²/c²)
  y' = y
  z' = z
  t' = (t - x*v/c²)/sqr(1 - v²/c²)

where:

 x, y, z, t coordinates in inertial reference system K,
 x', y', z' , t' coordinates in inertial reference system K',
 v the relative velocity between inertial reference systems;

also, the expression 1//sqr(1 - v²/c²) is known as the Lorentz factor.

The Lorentz transformation equations are a more general case of the Galilean transformation:

  x' = x - vt
  y' = y
  z' = z
  t' = t

which is the basis of the assumptions of the classical mechanics as to the absolute character of both dimensional and temporal coordinates. The above are the result of replacing velocity c with ∞ in the Lorentz transformation equations.

The Lorentz transformation has a few corollaries which have an impact on time dilation, length contraction, relativistic mass, relativistic momentum, and relativistic kinetic energy. The one that concerns us is the time dilation corollary:

 Δt = γΔt'
 
where γ is defined by

 α = 1/γ = sqr(1 - v²/c²)

Assuming a clock at rest in inertial reference system K, and moving with the velocity v in the inertial reference system K', the time Δt' between two ticks as measured in the frame K' is longer than the time Δt between the same ticks as measured in the rest frame of the clock, K.

Relativistic Effects on Proof-of-Work

To better understand the relativistic effects on how relative time is perceived in two inertial reference systems (or Galilean reference systems [EINS]) we have to mention the twin paradox. The twin paradox is a thought experiment that involves two identical twins. One of the twins makes a journey into space onboard a relativistic spaceship, and upon his return to Earth discovers that his twin has aged much more than he did. Depending on how fast the spaceship moves through space and/or how long the journey was, our traveller could return to Earth and realize that several generations have passed meanwhile.

As a direct application of the twin paradox, we have Mazer Rackham, International Fleet Admiral and Ender Wiggin's mentor, as portrayed by Orson Scott Card [CARD]. The fighter pilot who destroyed the Formic Fleet Flagship, killed the Hive Queen, and ended the Second Formic Invasion, Mazer Rackham is sent on a journey on a relativistic spaceship and returns to Earth 100 years later in order to assist the International Fleet. Upon his return he has barely aged a few years.

Similarly, if a subnetwork is moving relative to the rest of the network, the nodes in the subnetwork would experience time dilation as predicted by the special relativity theorem. Hence, they are at a disadvantage compared to the rest of the nodes because they have less time available to find a solution for the proof-of-work problem. In order to make thing square for all the nodes in the network, the difficulty of the problem should be adjusted in each subnetwork using the Lorentz factor: in order to compensate for time dilation, the relativistic nodes should have to solve a simpler problem. Also, their block confirmation time should decrease as well.

One element is missing still... how do ansibles synchronize? What value has the Lorentz factor for each one of them? One simple solution for this problem is having one of the ansibles (let us say the Earth-bound one) broadcasting a beacon every fixed number of seconds. The ansibles interfacing to subnetworks would pick up the broadcast, and by measuring the time interval between the beacons, infer the Lorentz factor. Once the Lorentz factor is determined, the nodes mining on the subnetworks will have their proof-of-work difficulty and the block confirmation time adjusted accordingly.

A more Down-to-Earth Solution for the Problem

We will fork the storyline (pun intended) at Enter the Ansible paragraph, and suggest a more down-to-earth solution for the problem. The peripheral nodes are not to participate in the consensus. Their function would be just to relay messages (a.k.a. payment information) across the network. In our multi-planetary scenario, the nodes working on the proof-of-work would reside on/around the Earth, and the network nodes on Mars or any other region in the Sol system would have to wait 2x (network packets travel time) + (block confirmation time) in order to confirm a payment. However, such a solution would have an Achilles heel very hard to defend... if starting its mining engine, any peripheral node could take over the local network and force a topological fork of the network. For a node, the incentive of staying honest on the current network must be stronger than any reward obtained by cheating.

Concluding remarks

While the blogpost contains some elements of fiction, it accurately describes the cryptocurrency ecosystem, the special relativity theorem, the Lorentz transformation and its corollaries. We would like to thank the readers that went through this exercise with us. Undeniably, cryptocurrencies are disrupting the global economy and they are here to stay. Undeniably, we -- as a species -- will explore and migrate farther than the LEO. History has taught us that decentralization is the key to survival and prosperity. Let us together make the future happen.

References

[ANTO] Antonopoulos, Andreas M., Mastering Bitcoin, Second Edition, O'Reilly Media, Inc., June 2017;
[CARD] Card, Orson Scott, Ender's Game, A Tor Teen Book, 2014;
[EINS] Einstein, Albert, Relativity, The Special and the General Theory, Princeton University Press, 2015;
[LEGU] Le Guin, Ursula K., Rocannon's World, Harper & Row, 1977;
[NAKA] Nakamoto, Satoshi, Bitcoin - A Peer-to-Peer Electronic Cash System, www.bitcoin.org, 2008;