Panel Recommends Space Science, Not Stunts

wisebabo writes "A panel reporting to President Obama is recommending that we skip landing on the Moon and Mars and instead consider progressively deeper space voyages (first to the L1 Earth-Moon point, then perhaps the L2 Earth-Sun point, then a Mars flyby/orbit or asteroid visits). While in Mars orbit, the astronauts could send robotic probes to land on the surface, which could be much more effective than current rovers without the 10-minute time lag to Earth. I, for one, whole-heartedly agree that this approach would lead to 'the most steady cadence of steady improvement,' and keep us from inconsistent achievements in space (like not leaving Earth orbit for 40 years). Some would say that this approach would be lacking in the photo-ops necessary to maintain interest in the space program (no footprints on Martian soil) but I think there would be plenty of cool vistas — perhaps a rendezvous with a comet, or even orbiting one of the moons of Jupiter, assuming they figure out radiation shielding — to keep the taxpayer dollars flowing. The science return would be much greater because it would hopefully utilize both man and machine at their best; robots on one-way trips down into a gravity well while the humans provide the intuition and flexibility from orbit."

Comments

Martian Time Slip

[mbone]

than current rovers without the 10-minute time lag to Earth.

At opposition, the average round trip time (RTT) to Mars is 9 minutes.

At superior conjunction, the average RTT to Mars is 42 minutes.

At other times, the RTT will be in between these two values.

Both of these numbers will vary at the 10% level due to orbital eccentricities and inclinations, but, clearly, most of the time the RTT will be greater than 10 minutes.

However, this is almost irrelevant. All currently and planned rovers or landers use "bent-pipe tracking," where data is sent to an orbiter, and then the orbiter, sometime later, sends it to the Earth. This greatly increases the effective RTT (there are not orbiters passing over any given surface location at any time).

I believe that the Phoenix, the current rovers, and the Mars Science Laboratory all basically plan on an effectively daily RTT (i.e., at best one up and down link per day). These long effective RTTs and the use of orbiters to store-and-forward data are part of the motivation behind the efforts around Delay / Disruption Tolerant Networking (DTN) - AKA the Interplanetary Internet.