A quick reminder for Trekkies

Posted on 19 May 2013 by Joseph

In Star Trek II: The Wrath of Khan, the legendary genetically superior super-bad-guy mastermind genius Khan is defeated by a plot hole.

Allow me to explain: Khan, on board the USS Reliant, is fighting the crew of the USS Enterprise and about to blast them into oblivion when Spock identifies that Khan’s strategic thinking is hampered by his twentieth-century roots. He is treating space like a two-dimensional battlefield. So, the Enterprise sneakily moves vertically relative to Khan’s ship, thus disappearing from Khan’s radar. Moments later, they pop back and obliterate the bad guy.

Okay, first of all, if Khan’s strategy was truly two-dimensional in nature and Starfleet is supposed to be at all effective as a spacefaring organization, then “engage standard battle plan alpha that they teach first-years at the Academy!” should have been sufficient to destroy him. Because any such basic plan will use three-dimensional movement. After all, these plans have been honed by years of war with the Klingons. So, yeah – Kirk ought to have beaten Khan by rote.

Second, the Reliant’s sensors ought to have given some indication that the Enterprise was moving vertically. And they ought to have given some indication of when the Enterprise was coming back into range. The Enterprise, apparently, was able to track Khan’s position while doing its little up-and-over maneuver. Why not the reverse?

Third, the Enterprise crew decides to pop back into the 2D plane before attacking, instead of doing a smarter Princess Leia-style surprise attack from above. Here’s how I think this would have played out in Khan’s mind: “WTF? Where’d they go? Look everywhere in 2D for the Enterp–oh, there they are. Open fire.”

Plus there are all the other weird devices in the story…the Genesis Device is really no better than red matter. We’re supposed to take it that out of all Kirk’s flings in the original mission, somehow he had the most special feelings for this woman we’ve only just met, and we’re only told about that past relationship. And what’s up with his son? My point: I’m not really sure why Wrath of Khan is the sacred cow it’s made out to be. (Personally, I’m more a fan of IV and VI.)

Incidentally, I liked Star Trek Into Darkness.

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Spacecraft Research is at it again

Posted on 10 May 2013 by Joseph

It’s been a little while since I checked in with the goings-on back at my Cornell research lab. Totally unsurprisingly, some very cool things are happening there!

One is that the Sprite and KickSat project has gone all the way from a back-of-the-envelope concept when I was at the lab to a flight manifest! Sprites are tiny spacecraft – think the size of a coin – that consist of little more than a solar cell, a little CPU, and a diminutive radio. They are pathfinders for an idea that, rather than relying on a single monolithic (and super-expensive) spacecraft, instead we could just run off a batch of a million tiny satellites and fling them all out into space to cooperatively complete a mission. Some of the applications we talked about included integrating basic lab-on-chip functionality to test for biomarkers, and then rain a bunch of the Sprites down onto Mars or Europa. They wouldn’t return the same wealth of data of a NASA flagship mission, but they would tell us where the interesting things are. Another reason why tiny spacecraft are cool is because they interact differently with Solar System objects than large vehicles do – so they might be able to take advantage of light, magnetism, or planetary atmospheres in different ways.

The KickSat project was the brainchild of grad student Zac Manchester. It’s a simple CubeSat design with a spring-loaded deployer, designed to release a couple hundred Sprites. On the ground, Zac can then track the intermittent radio signals from all these mini-spacecraft, and evaluate how well their unshielded components survive in space. Radiation will eventually kill them, but with many copies of the same spacecraft, we’d expect to see them die out statistically. They’re spacecraft with a half-life, and as long as the half-life is long enough to complete the mission, we don’t care that a huge number of Sprites burned out.

When I left the lab, Zac was applying for grants to build the KickSat hardware. But – despite the cool concept – there weren’t any takers. Eventually, he decided to turn to KickStarter to see if he could crowd-fund some spacecraft research. He ended up raising almost three and a half times as much money as he asked for, and become something of a pioneer for crowdfunded space activities! Zac is now working at Ames Research Center to perfect the Sprite and KickSat designs. They will be launching on the same SpaceX Falcon 9 rocket that will carry supplies to the International Space Station in September. This is actually the first CubeSat from my lab to make it all the way to launch, so I say: Go Zac!

Second, a project that is perhaps a little less flashy but a little closer to my heart has been making some great strides. Ben Reinhardt has been squirreled away in the same basement lab I remember, working on what he calls “eddy-current actuators.” The more fanciful – and very nearly accurate – name for the devices he is working on would be “tractor beams.” He wants to use these to grab onto defunct satellites, the outside of the Space Station, or maybe even some asteroids and comets, all without mechanical contact.

I was still active in the lab when this project got off the ground. In fact, I put together one of our first tabletop demonstrations of the principles involved: a changing magnetic field generates eddy currents in conductive materials; these currents have their own magnetic fields which we can push or pull with magnets. That’s where I left the project, though…a quick video where I waved a magnet around, some rough number-crunching to show that the induced forces were feasible for applications, and then I was out to let other members of the lab hash out the details. (That’s the fifth-year grad student for you!)

The cool news is that Ben has gone from my rough video to a much more carefully controlled demonstration. He’s generated attractive and repulsive forces in a bare piece of aluminum (not unlike the skin of a spacecraft), without touching it, and he’s working on characterizing the design space of his device. This is a critical step in figuring out how to go from proof of concept to a useful technology, and it’s a step I remember quite well. While Ben’s twitching pendulum might not look to you like the tractor beams from Star Trek, it is a clear and measurable experiment illustrating the device. I went from similar experiments in my first two-ish years of grad school to flight demonstrations in my third and fourth; I hope Ben follows a similar trajectory. And who knows – if some companies or space agencies take an interest, we may soon see spacecraft grappling asteroids and assembling components with eddy-current tugs!

Ben and some of the other Cornell Space System Design Studio grad students are keeping a blog about their technology research projects, which you can read here. I think it’s very cool to see what’s going on in the lab!

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CubeSailing

Posted on 7 May 2013 by Joseph

Way back when I was looking at grad schools, I visited an MIT space propulsion lab where students and faculty were developing something called an electrospray thruster. This is a device consisting of a plate covered in tiny spikes, with a tiny grid layered on top. You feed an ionic liquid onto the plate, where surface tension wicks it up to the tips of the spikes. (Ionic liquids – and this kind of boggled my mind when I first learned about them – are salts that are in their liquid state. They’re just a bunch of sloshing positive and negative ions. Wild!) Then, you apply a voltage to the grid sitting above the spikes. The potential difference between the spikes and the grid yanks ions up and hurls them out through the holes in the grid, and voila – ion thruster.

The MIT Space Propulsion Lab has been developing these as little patch thrusters that they can put on CubeSats. The thrusters are 1×1 cm patches and seem to generate forces in the range of ten or so micronewtons. (That would be, say, 1% of the weight of a postage stamp.) These are very small forces, but we are talking about very small satellites and we can leave the thrusters on for a very long time.

The idea that stuck in my head when I learned about these devices, though, is that they are mechanically very simple: all we have to do is texture a surface appropriately, touch the ionic liquid to it, and energize part of it. We could probably develop a fabrication method to print the thruster “texture” onto a flexible membrane or fabric of some kind.

And then we could deploy it like a sail.

10 micronewtons from a 1×1 cm thruster gives a thrust density of 0.1 N/m^2. So a 1×1 meter sail would produce a thrust force of about a tenth of a newton. On a standard 3U CubeSat, this corresponds to an acceleration of 3.4 milligees – which is actually getting up to the acceleration regime of the chemical thrusters on large spacecraft! With such acceleration, it would take five minutes for the CubeSat to add one meter per second to its velocity. Starting from low Earth orbit, this miniature sailing vessel would need only twenty minutes to hit Earth escape velocity!

3U CubeSat with 1 meter "pusher" sail

3U CubeSat with 1 meter sail

What probably makes the most sense from a propulsion perspective is to deploy the membrane engine behind the spacecraft, maximizing the engine area and minimizing any adverse effects of the ion exhaust. (All those high-energy ions might eat away at the spacecraft’s solar cells or other surfaces!) However, there might be some challenges in running the ionic liquid down to the sail.

A good compromise would be a sail mounted to the back or middle of the CubeSat – think of  the NanoSail-D configuration – where a reservoir of ionic liquid could supply a steady stream of propellant to the membrane and most of the zooming ions will miss the back of the spacecraft. The forward-facing part of the membrane might also be usable area, for things like solar cells. Or CCDs.

Ion engines caused a shift in the way spacecraft engineers thought about propulsion: instead of brief, impulsive maneuvers, they could use a gentle but steady acceleration for a long period of time. The ability to spread an ion engine over a large area might be a way to create a high-efficiency thruster that also produces a large force, and with few moving or complex parts. That’s the kind of device we might use to send a small spacecraft to the outer Solar System. Of course, we’d need a lot of electrical power, but that’s why the DOE is starting plutonium refining again…

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Antares and tiny satellites

Posted on 23 April 2013 by Joseph

This weekend was full of excitement for commercial space fans. Orbital Sciences Corporation launched the Antares rocket, making them only the second private company to put a vehicle into orbit. Like the SpaceX Falcon 9, Antares is intended to carry cargo to the International Space Station. Antares is cool for a couple of reasons – partly because it represents a further gain in the United States’ launch capability, but more notably because the target market for Antares commercial launches are smaller spacecraft than the usual several-thousand-ton geosynchronous birds.

Smaller spacecraft are particularly cool because – since their design, fabrication, and launch costs are lower than big satellites – satellite manufacturers are more willing to take risks with their design. I don’t mean “risks” to imply that these spacecraft are unsafe. I mean that they are not quite as tried-and-proven. In other words, they can be more cutting-edge. More innovative. More likely to push the envelope.

In that vein, what I find most exciting about the Antares launch is that the vehicle carried three NASA CubeSats specifically designed to puncture the conventional wisdom about how conservative spacecraft designs need to be. They are called “PhoneSats,” and what makes them special is that their flight computers are off-the-shelf Android cell phones. Their on-board avionics software is an app.

http://www.nasa.gov/directorates/spacetech/small_spacecraft/phonesat.html

PhoneSat 1.0 (from nasa.gov)

The idea behind these CubeSats is to test how robust spacecraft really need to be. Commercial spacecraft engineers design huge margins into their vehicles. We tend to be very careful and conservative. But since many spacecraft last well longer than their quoted design lifetimes…maybe we’re too conservative. The PhoneSats will help answer the question: If we just get commercial computer hardware and design a system that works – without so much conservatism – how long will it last in space? Maybe it will operate long enough to complete its mission.

If the PhoneSats stayed in orbit forever, they’d be likely to burn out. Their Android processors and flash memory would fail under the onslaught of cosmic rays. But, at under $7000 each, maybe even the short mission of these satellites would make them competitive with the longer-lasting multi-million-dollar vehicles.

I’ll be very interested in the results of the PhoneSat project!

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Where does the public see innovation?

Posted on 17 April 2013 by Joseph

The Lockheed Martin corporation recently conducted a poll in which they asked members of the public to choose the company’s “ultimate innovation.” There were a lot of fancy gizmos in the poll, including some very recent ones that definitely qualify as “innovations.” The Joint Strike Fighter, for example – a jet that can take off vertically and then fly at supersonic speed - is pretty damn cool. The SR-71 is almost mythic in the aerospace world. There were underwater robots and fighters that helped us win World War II.

But what won the poll, in the eyes of the public? What was the “ultimate innovation?”

A twenty-three-year-old clunker of a machine. A device that was once universally panned as myopic and wasteful.

The Hubble Space Telescope.

These high-profile space exploration missions simply soar in the public imagination. More than any other aerospace or engineering innovation, they capture people’s attention and fire their spirit.

Clearly, we need more of them.

Not only is it good policy…it’s just good public relations!

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A spacecraft engineer’s review of Flotilla

Posted on 12 April 2013 by Joseph

I just picked up the latest Humble Bundle sale entirely because of the gameplay video of Flotilla. Flotilla is a terrific little gem of a game that puts players in tactical command of a small squadron of combat spacecraft, with a little irreverent stomp-around-the-galaxy exploration to frame the battles.

Screenshot from the Flotilla web site.

What it gets right

Spacecraft physics-wise

The simultaneous turn-based mechanic. I’ve written before that a realistic movie depiction of space combat would play out like a submarine movie: long periods of tension between scenes of rapid action. Flotilla only allows players to issue orders every 30 seconds, and then watch how their tactics play out – which plays right into that tension/action dynamic. It also is probably pretty close to how communications lag and astronomical distances would force a true space fleet commander to operate.

The focus on both spacecraft position and orientation. Ships have well-defined firing arcs, strong points, and weak points. These features make it essential for players to consider the 3D orientation of their spacecraft and their targets: I learned very quickly that the basic orientation control mode (in which you specify an enemy for your ship to face) was not sufficient if I wanted to get through combat unscathed. The advanced mode (which lets you specify yaw, pitch, and roll Euler rotations for each ship) let me perform much more advanced maneuvers; faking out my opponents so that they exposed their vulnerable points to me while I absorbed incoming fire with armored surfaces.

Gameplay-wise

The simplified interface. The game is very clean, stylish, and accessible. It’s easy to set up complex tactics in the fully 3D environment. I also appreciate that you don’t have to keep track of a bazillion unit types and special abilities – but, at the same time, each ship class has particular strengths and weaknesses.

The combat balance. It’s possible to approach a battle with a large fleet and blast your enemies into space dust…and it’s also possible to slip in with a single destroyer and land surgical hits to wipe out a superior force. (It took a while, but about half a hour ago I took down two destroyers and four dreadnoughts with a single destroyer. I even tricked two of the dreadnoughts into colliding – that was very satisfying!)

What it gets wrong

Spacecraft physics-wise

The specifically top/front armor design. All ships have strong armor on their “tops” and “fronts,” with weak armor on their “bottoms” and “rears.” I think it’s great to have weak and strong faces, but if the engineers who designed these ships knew that they were going into space – where only the enemy’s gate is “down” – why would they make all ships the same in this regard? It would make more sense for the different ship classes to have different strong and weak faces.

Forces do not exist. There is no gravity, and no orbital motion. All battles take place in deep space. Orbital dynamics would certainly complicate the gameplay – but the cool thing about including orbits would be to add complexity to players’ tactical options. (In orbits, it’s actually easier to move in some directions than others. That’s a phenomenon that players could manipulate.) More importantly, the direction a ship’s engines are pointing has no effect on its motion. It would have been neat to see some coupling between the 3D positioning and spacecraft orientation, instead of letting vehicles slide “sideways” at the same speed that they move “forward.”

Gameplay-wise

No collision warnings. The movement hint lines really need to turn red or something when you accidentally drive them through an asteroid. Or when two ships’ movements will lead them into a collision halfway through your turn. Even after I knew to look out for these situations, I still sometimes drove my own spacecraft into each other. Those are real facepalm moments!

Orientation can be tricky. While I love the abstracted spacecraft graphics because they make me feel like a fleet admiral looking at a tactical display, it’s sometimes hard to tell at a glance which spaceship faces are “up.” A little extra coloration or something would help indicate the weak and strong spots. In addition, Euler angles are not my favorite way to represent and manipulate orientations of spacecraft. I would prefer to use the same planar/vertical interface that sets 3D motion to specify the front-facing direction of my ship, and then roll the spacecraft about that axis.

What it gets hilarious

Everything about the Adventure Mode. That owl warlord will rue the day he challenged my karaoke championship!

 

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On the World Zarmina

Posted on 7 April 2013 by Joseph

…Preliminary report on image data from the LongShot-2 mission…

The planet Gliese 581g – also known as Zarmina – is a circular world.

It is not circular in the literal sense shown on pre-Columbian maps of the Earth, before we understood Earth to be a sphere. Rather, Gliese 581g spins at the same rate as it orbits its star, so its sun is always in the same place in its sky. Heat from the red dwarf, distributed by the circulation of the atmosphere, keeps a circular region under the star warm enough to melt ice into liquid water.  Thus, the habitable regions fall entirely within a disc under the constant light of the red star. Outside this region, water freezes – and the further one goes out onto the ice, the more inhospitable it gets. Travel to the far side of the planet is about as difficult as traveling from the Earth to the Moon – and so, to the inhabitants of Zarmina, their world might as well be a circle ringed in ice.1

This artist’s concept, based on image mapping from our recent interstellar probes, depicts the habitable region of Zarmina:

Zarmina, from above the substellar point

Zarmina, from above the substellar point.

For discussion of Zarmina, some reference points and directions are necessary. The circular boundary of the map is the ice line: beyond this point, water is certain to freeze. The center of the circle thus defined is the substellar point. When standing here, the red dwarf Gliese 581 is directly overhead. This image shows Zarmina oriented with is orbital plane horizontal. The planet has a north magnetic pole pointing roughly towards the top of the page, and so the “top” and “bottom” of this map become the cardinal directions north and south. East and west take on their usual definitions.

Gliese 581g is approximately three and a half times the mass of Earth. It is tidally locked to its star, meaning that one side always faces its Sun just as one side of the Moon always faces the Earth. Gravitational tides from the star also have the effect of pulling the rocky surface of the planet into an oblong shape, like a rugby ball. Since our probes reached the Gliese 581 system,2 we determined that the planet has a tiny orbital eccentricity (from perturbations by the other planets in the system) which causes a periodic shift in the gravity force on the planet: slightly east to slightly west, and back again, every Zarminan day (about 37 Earth days). The combination of the periodic variation in stellar tide and the fact that the ocean is more mobile than rock makes dry land much more common in the center of the disc than near the edge, as we see in the map.3

This variation in tidal force results in one of Zarmina’s most striking surface feature types. Continue reading →

Posted in Art, Concepts, Geology, Maps, Original fiction, Science Fiction, Space | 2 Comments

Profile on Dice

Posted on 16 March 2013 by Joseph

So, I’ve been profiled as “Featured Geek” on Dice.com. Here is the article.

If you found your way here by way of Dice, here’s a teaser for something I’ve got coming up…

geological map teaser

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Marswhelmed

Posted on 15 March 2013 by Joseph

So, the Mars Science Laboratory “Curiosity” has discovered evidence that, about three billion years ago, the environment on the planet Mars could have supported Earth-like microbial life. Some news outlets (including the MSL Twitter feed) are billing this discovery as the accomplishment of Curiosity’s mission.

I have a confession to make.

I don’t really find this discovery all that exciting.

The MSL team’s discovery is a confirmation of a long-expected hypothesis. (Indeed, with the number of planetary environments out there, it would be statistically silly to think that Earth is the only life-supporting place!) It’s valuable to know, and it’s important to the scientific method to rack up such confirmations even when we’re as sure as we can be, but it doesn’t exactly have the same allure as striking out into the unknown. I think the spirit of exploration is important to maintain in our space programs, because brand-new missions and discoveries are what keeps space exploration in the public eye. After all, a recent study shows that not only do most Americans want to see exploring Mars as a national priority, but most Americans want to see a human mission to Mars and three-quarters of Americans want to see the NASA budget doubled. I am confident that the dramatic landing of the Curiosity rover, with its brand-new mission architecture, has something to do with that enthusiasm.

There’s also something I find slightly foreboding about Curiosity’s confirmation. In 2011, the National Research Council’s Planetary Sciences Decal Survey of Solar System exploration listed and prioritized the objectives of our planetary science program for 2013 through 2022. This is a study done every ten years to identify which of the flagship-sized missions NASA should fund, design, and launch in the coming decade. First on the list for 2013-2022: a mission to return samples of Martian rock and soil to Earth. The announced “Mars 2020″ rover is in line with that objective.

I’m going to go out on a limb and predict the conclusion sentence of scientific findings from a Mars sample return mission:

Chemicals and minerals present on the surface of Mars indicate that ancient Mars may have included wet environments able to support Earth-like microbial life.

In other words, I don’t think a Mars sample return mission will give us any dramatically new information that we didn’t already have from MSL, MER, MRO, or any of the Martian samples we already have. See what’s got me worried? I don’t think we’re going to actually discover life – in fact, I would be very surprised if the 2020 rover included any instruments actually capable of recognizing a Martian if it walked right up, poked the rover with a Martian stick, and walked away. (Curiosity doesn’t!) I am afraid that we will put this rover on the Red Planet in 2020, cache a sample, retrieve the sample in 2030, and the public response will be, “wait a minute, we spent two decades confirming what we already knew in 2013? Come on, space program…where’s my jetpack?”

A Mars sample return mission would be a triumph…for the niche sub-field of Martian geochemistry. I don’t think it would have the sort of broad scientific and public impact that we should expect from a flagship-scale mission. Basic research science plods along, making incremental improvements in understanding and slow-but-steady progress. NASA should be sticking its neck out, thinking big, and going for the most challenging – and rewarding – missions. Instead of looking for environments that might have been habitable three billion years ago, we should be looking for actual life.

You see, even before MSL’s discovery, we already knew of the existence of a watery, potentially life-supporting environment. Jupiter’s moon Europa has an icy crust with a subsurface water ocean beneath. The ocean is warm enough to be liquid, because of the energy input from Jupiter’s tides. And scientists have found that that ocean contains lots of salts and minerals – and even organic (carbon-containing) compounds. Liquid water, energy sources, and chemical building blocks: everything an Earth-like life form needs! The main difference between Europa and Mars is that, while we’ve been able to observe the desolation of the Martian surface for decades and know that we could only expect to find evidence of ancient microbes, we have no idea what’s under the Europan ice sheet. It could be nothing…but it could also be life as rich and complex as what we find, on Earth, under Antarctic ice, in sealed cave systems, or around hydrothermal vents. Unlike Mars, where we have been forming preliminary conclusions for years, we won’t know until we get something under that ice layer. That’s the kind of exciting exploration work that I want to see from my NASA flagship missions.

The Decadal Survey did recognize the potential for alien life on Europa. Its executive summary says that “the second highest priority Flagship mission for the decade 2013-2022 is the Jupiter Europa Orbiter” but notes that “that both a decrease in mission scope and an increase in NASA’s planetary budget are necessary” to fly a mission to Europa. Personally, I’d prefer to discover alien creatures within my lifetime…but I don’t make policy or control the purse-strings. So, instead, off to Mars we’ll go again.

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Heritage

Posted on 13 March 2013 by Joseph

Today, I saw a piece in The Space Review about what makes spacecraft launches complex and difficult. It occurred to me that this was a rather odd essay, coming as it does on the heels of the successful, high-profile flight test of a rocket that promises to seriously shake up the launch game. The essay is a full-throated defense of the Old Launch paradigm; the idea that the people who have been approaching space the same way for decades are the best at it by virtue of their heritage. If this essay had come out a few years ago, when SpaceX was experiencing strings of launch failures, it might be relevant; but now it is a perfect illustration of what’s wrong with space industry thinking.

Building and launching spacecraft is hard, no doubt about it. Satellites and rockets are complex systems. A lot of things have to happen very quickly, and some things have to happen in regimes where we don’t fully understand all the physics. The success rate for space missions is not 100%. (These days, though, it’s pretty darned close.) However, the inherent difficulty and complexity of space exploration and exploitation is a poor reason to shy away from innovation.

The Space Review essay opens with the following paragraph:

One of the most challenging aspects of launching payloads into space is that you not only get only one attempt for a particular set of hardware, but usually that one attempt is the first time that particular set of hardware experiences the actual flight environment. It may even be the only time that overall hardware configuration ever flies. Every flight is a test flight, like it or not. For that reason it is very, very important that the hardware gets built every single time in exactly in the same manner of other examples that were found to work properly. This is not easy; in fact, it may be hardest single requirement in the space launch business.

I’ve added some emphasis to a statement with which I cannot disagree more. The author says that the most important requirement for space hardware to meet is that it should be exactly the same as other space hardware that has already flown.  I think that what he should say instead is that it’s important to be sure that your hardware will work. Whether you prove that by simulation, analysis, experiment, back-of-the-envelope calculation, derivation, or by comparison to flight heritage is immaterial to me!

I think that this notion of valuing flight heritage above all other considerations is detrimental to the space industry, for a couple of reasons. First, it stifles innovation. If, over the past sixty years, we really hadn’t sent anything into space that hadn’t already been in space, we wouldn’t have any satellites at all. Or, if I’m going to give humanity the benefit of the doubt, we might have a couple satellites but they would all look like this. Space is a challenging but rewarding environment. Purely in economic terms, it’s worth it to stick our necks out a little and accept a couple failed launches in return for all the infrastructure that we have been able to deploy in space, from weather satellites to Earth imagery to military support. The more capabilities we want from our spacecraft, though, the more we need to innovate. Sometimes – heck, often - that means we have to build a vehicle that looks different from the things that have gone before.

Second, I don’t like the idea of flight heritage because it involves an implicit logical fallacy. Spacecraft engineers sometimes confuse a solution that worked in the past with the best solution to a problem. Sometimes, spacecraft launch with really state-of-the-art devices and programming. But, other times, they launch with only good hardware and software. Every now and then, they even launch with something on board that’s actually sub-par – and sometimes, that causes a problem. An engineer might think that if a design has heritage, it’s certain to work. But no such guarantees for success actually exist. Spacecraft are not like mass-market consumer goods: we can’t test thousands of samples and get a good statistical sense of whether we have the best design or not. We have to deal with small-number statistics for successful missions.

It’s important to look at spaceflight heritage with a critical eye: What worked? What didn’t? And why? Do we have the best solutions? Can we make them better? If so, what would it take? These are questions that drive innovation. They are more likely to come up at a New Space company – which has to innovate in order to survive – than an established Old Space company. I have great respect for the engineers that have been able to launch whole series of operational spacecraft. But I am wary of an approach that views prior success as a standard of perfection.

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