Given all the attention that it is receiving, the innovative technology that will place the Curiosity rover on Mars — the sky crane — may seem like something that we’ll be seeing much more of during future space missions. Yet it’s not. In fact, there’s good reason to suspect that it will be a long time before the sky crane is used again on Mars, if ever.
Of course, its prospects do depend on the success or failure of the Curiosity landing, but let’s hopefully assume the best. [Update, 1:36 a.m. EDT, Mon.: The best occurs! Success!] Instinctive skepticism has always greeted the plan: it is complicated and unorthodox, and a mishap anywhere along the chain of feats in involves leads to disaster. Even those of us enthusiastic about the sky crane have often conceded that it sounds crazy but might just be crazy enough to work. Even that skepticism, though, isn’t exactly why the sky crane won’t be selected for many other missions.
The absence of the sky crane might seem all the more surprising given that NASA’s rationale for using it with Curiosity has always been that it had no good alternatives. As I explained in my SmartPlanet column about it, technologies used to land other probes on Mars hit their limits with something the size and weight of the Curiosity rover. Parachutes can’t slow the craft enough in the thin Martian atmosphere for a soft landing. Airbags can absorb the force of a landing impact for the 400-lb. Spirit and Opportunity rovers but not something as big and sensitive as one-ton Curiosity. Rocket thrusters, the old reliable standby, can do it but at the cost of disrupting and polluting the landing site.
So then why wouldn’t the sky crane be the method of choice for upcoming probes? Because the sky crane is an expensive technology developed by NASA, and NASA is temporarily getting out of the Mars lander business.
NASA expects to get years of good results out of Curiosity, so it won’t be idle on the Mars front. Nevertheless, the only mission concretely on its schedule now is the Mars Atmosphere and Volatile Evolution (MAVEN) orbiter, set to launch in 2013, which will study the planet’s upper atmosphere. It won’t be sending anything to the surface at all. NASA has long-term Mars exploration plans that would repeatedly take it to the surface — with balloons, aircraft, deep-drilling probes, more rovers, and even rockets capable of returning samples to Earth — but none of those has been scheduled or funded yet, and the cloudy condition of the economy makes it unclear when they will be.