[ExI] James Oberg on a flexible future for NASA

BillK pharos at gmail.com
Mon Sep 14 08:02:47 UTC 2009

On 9/14/09, spike wrote:
>  My earier comment should not be taken as my agreement with everything
>  Oberg says in there.  One paragraph in particular I would take exception, the >  part where he talks about astronauts operating robots on the surface of the
>  moon from lunar orbit.  With this I mostly disagree, for in every calculation I
>  have attempted, I have never been able to justify the complication and cost
>  of keeping proles up there just to eliminate the 1.5 second latency in
>  operating the same lunar surface robots from good old home base.  We can
>  operate robots 1.5 seconds away.
>  On the other hand, operating surface robots from Martian synchronous orbit
>  is justifiable, for a bunch of reasons.  The 2 to 15 minute drive from Earth
>  to Mars makes it wildly difficult to operate robots from here.  Also the
>  solar radiation dose to the astronaut is only about a quarter in Mars orbit
>  of what it would be in the lunar orbit.
>  So I have long ago concluded the way is insert into Mars orbit, one
>  astronaut, stay until the orbits of Mars and Earth again allow, return,
>  total mission time about three and a half years, total delta vee required
>  isn't all that much higher than we did for the Apollo missions.  Start with
>  a small, young and light enough astronaut, good chance she would not suffer
>  permanent damage to her health.

Speed of light - 299792 km/sec.

Distance to Mars  - 55 to 401 million kilometers.
Transmission time - 3 to 22 minutes.
Round trip transmission - 6 to 44 minutes. (plus thinking time)

Distance to Moon -  363300 to 405500 km
Transmission time - 1.2 to 1.35 secs.
Round trip time - 2.4 to 2.7 secs. (plus thinking time)

Considering the many years and much expense that it will take to
develop a manned expedition to Mars, I suspect that by the time the
expedition is ready to go our exploration robots will be able to
manage quite nicely by themselves without human intervention. And even
if we lose a few robots due to accidents, then no problem, there's
plenty more.


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