The driver who took me from Aosta to Milan yesterday evening spoke no English, but he was an affable young man who had a love for fast cars. As we drove along a fine Alpine highway, a low red sports car moved fast us so quickly that I almost didn’t see it. But suddenly the driver, who had said next to nothing thus far, erupted with “Italian car! Beautiful!” He stretched out the last word as if savoring the idea, then looked over at me making a thumbs up. Well, it was beautiful, and it was followed by two more similar cars making speeds I could only guess at. I wondered what it felt like to drive such a car, and how quickly it would get to Milan.

One of the best things about wrapping up the Aosta conference, which we did with a farewell party yesterday afternoon, is that I head back to the States with a satchel full of papers. I’ve only been able to mention a few of them thus far, but next week I should have the chance to talk about them at more leisure. Here in Milan I have a few minutes before I have to leave for Malpensa airport, so I thought I would mention Greg Matloff’s paper on using Near-Earth Objects in a novel and intriguing way. Greg (New York City Technical College, CUNY) has a student named Monika Wilga who worked with him on the concept of using NEOs to hitchhike to Mars.

Now Mars wouldn’t seem to have much to do with this conference, because it is, after all, explicitly focused on missions to the outer Solar System and beyond. But it turns out there is an interesting outer system component here, not to mention a fascinating concept in and of itself. Greg put Ms. Wilga to work on finding any NEOs that cross close enough to Earth to make a mission there a viable one within a relatively short time, thus minimizing the danger of exposure to high-energy cosmic rays, whose health hazards on a long mission could be severe. He then asked her to further constrain the list to those NEOs that went on to pass close to Mars.

Image: Greg Matloff, taken at our visit to Giancarlo Genta’s summer house high above Aosta.

The idea here is that the astronauts can use the NEO as a radiation shield, digging in to its surface and exploiting its resources on the way to the red planet. Greg presented a table showing candidate objects that could fill the bill, including two — 1999YR14 and 2007EE26 — that have one Earth-Mars transit time amounting to one year or less. Let me quote the paper (and then I need to pack it and get going to Malpensa):

Since orbital characteristics are known for a few thousand NEOs, it is reasonable to assume that about 0.1% of the total NEO population could be applied for Earth-Mars or Mars-Earth transfers during the time period 2020-2100. Because a few hundred thousand NEOs must exist that are greater in dimension than 10m, hundreds of small NEOs must travel near-Hohmann trajectories between Earth and Mars or Mars and Earth. It seems likely that a concerted search will find one or more candidate NEOs for shielding application during any opposition of the two planets.

The outer system wrinkle to all this is that when Greg had his student repeat the study with the maximum aphelion distance of the NEOs stretched to 2.5 AU, no new Earth-Mars candidates were found. But a NEO called 2000WO148 passes Earth in January of 2041 and goes on to the main belt asteroid Vesta in October 2043. Now there’s an interesting mission possibility built right into the local NEO population. We should be able to find more candidate NEOs as detection sensitivity increases, so human journeys to other main-belt asteroids by this method may become feasible. Fascinating stuff and I’d like to say more, but I have a plane to catch.