[EAS]Furthest Manmade Thing

[pjk]

Subject:   Furthest Manmade Thing

Dear Colleagues -

As it reaches the edge of our solar system, Voyager 1 surely stands as
one of our most remarkable engineering achievements. Not all that
modern in hardware and software, since it was launched in 1977, but
astonishingly durable. What do you own that has been operating
continuously since 1977?

A Scout Report "In The News" item provides a comprehensive set of
perspectives and links
<http://scout.wisc.edu/Reports/ScoutReport/2003/scout-031107-inthenews.php#1>

and a recent "Physics News Update" shows that even the edge of our
solar system is subject to debate:

> PHYSICS NEWS UPDATE
> The American Institute of Physics Bulletin of Physics News
> Number 661 November 11, 2003   by Phillip F. Schewe, Ben Stein, and
> James Riordon
> 
> THE FURTHEST MANMADE THING, the Voyager 1 spacecraft, has recently
> detected a change in its local environment in the form of a greatly
> enhanced density of energetic particles.  Two papers published last
> week in Nature give different interpretations of the change.
> Krimigis et al. believe that Voyager has finally begun to encounter
> (at a distance of 85 astronomical units or 85 times the Earth-Sun
> distance) our solar system's "termination shock," the region of
> space where the outward going river of solar particles flags from
> supersonic to subsonic speeds in its confrontation with the
> interstellar medium.  One would expect the shock front to be a good
> accelerator of particles, and the observed upswing in fast particles
> is suggestive.   McDonald et al., however, argue that Voyager has
> not yet reached the termination shock, citing the relatively
> unimpressive presence of one species of energetic particles, namely
> so called anomalous cosmic rays. (Nature 6 November 2003.)  Voyager
> 1 and its twin, Voyager 2 (some 20 AU behind in the effort to leave
> the solar system) were launched way back in 1977.
                                                                        	
If you want to know more about the challenges that the space
environment creates for designers, I refer you to, e.g., NASA
Reference Publication 1390 "Spacecraft System Failures and Anomalies
Attributed to the Natural Space Environment:"
<http://trs.nis.nasa.gov/archive/00000318/01/rp1390.pdf>

    --PJK