lin liangtai

Why can't NASA turn a few more rocks on Mars to see if they are
fossils or not?

Mars Lander Phoenix turned a rock nicknamed “Alice” in
“Wonderland”(Ref. 1).
Why can't NASA turn a few more rocks to expose the unweathered and
articulated tissues under the "rocks"?
It is the easiest way for Phoenix to verify or refute the existence of
fossils on Mars. Why spend so much time for one oven test but
disregard the easiest way?

Ref. 1:
http://www.wretch.cc/album/show.php?i=lin440315&b=20&f=1555128094&p=27
(Lateral view of “Alice” in “Wonderland” before it was turned by
Phoenix)

http://www.wretch.cc/album/show.php?i=lin440315&b=20&f=1555161103&p=68
(Bottom view of “Alice” after it was turned by Phoenix, exposing a
skull's bottom)