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.


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.  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.