View Single Post
  #4  
Old January 12th 18, 11:27 AM posted to sci.astro.research
Steve Willner
external usenet poster
 
Posts: 1,172
Default Astronomy and Biology

In article ,
jacobnavia writes:
There are no specific sensors looking for life in [Mars rovers]
(there isn't even a microscope),


[[Mod. note -- Some experiments specifically designed to look for life
were landed on Mars in 1976. They found some surprising chemistry, but
no unambiguous evidence of life:
https://en.wikipedia.org/wiki/Viking_program

The underlying engineering problem is that while detecting macroscopic
life is fairly easy (take pictures of it), detecting *microscopic* life
requires fairly heavy/bulky equipment which is normally designed to be
operated directly by skilled humans. So doing this by remote control
from 45 light-minutes away (and with zero ability for a human to fix
anything that doesn't work) is hard, i.e., difficult to develop and
make work properly. That difficulty means lots and lots of engineering
person-years to develop the mission, which makes the mission very
expensive (on a scale of planetary-science budgets).

Given a budget of (say) 5e9 {US$,Euro}/year, one could do some very
sophisticated searches for life on Mars. But the actual worldwide budget
for all Martian exploration is well under 0.5e-9 {US$,Euro}/year, so
progress is slow.

And despite what optimists like Zubrin/Musk might say, sending (living)
humans to Mars wouldn't be cheap, either.
-- jt]]

There's no high-magnification microscope, probably because preparing
samples for one would have required complex and heavy
instrumentation. MAHLI has a resolution of around 25 microns
https://msl-scicorner.jpl.nasa.gov/Instruments/MAHLI/
but I don't know how useful it has been in practice.

Life has metabolism, and the effects of that metabolism are gases that
are produced as side effects of being alive. Methane is one such a gas.


I wouldn't mind seeing a chiral labeled release experiment sent to
Mars, but so far it hasn't ranked high enough in the priority lists.

In desperation I wrote in an ISS astronaut's web site a letter to him.


The human spaceflight program is quite separate from the planetary
science program. See nasa.gov for contact addresses for the latter.
Even for human spaceflight, the astronauts do not make policy, though
they certainly influence it.

Where is everybody? said von Neuman.


Fermi. The Fermi Paradox is a good argument against intelligent
extraterrestrial life, though it is far from conclusive.

Well, in any case they do not use radio waves, why should they?
Neutrinos are much better for communications since they aren't deflected
by matter as photons are.


Neutrinos are hard to detect. You might want to compare the
respective energy requiremets.

To find something, you have to believe it exists.


Yes, that's why Galileo never found sunspots or the moons of Jupiter:
he had no pre-existing conception that they existed. ... Oh, wait...

For instance dark matter.


No doubt Fritz Zwicky found dark matter only because he believed it
existed and was looking for it.

Actually, the history is the other way around: astronomers were
unwilling to accept dark matter -- despite strong evidence -- until
the evidence became overwhelming.

Many astronomers believe this thing exists and they try (with no
success so far) to measure a consequence of that hypothetical object.


Galaxy cluster velocity dispersions? Galaxy rotation curves?
Microwave background fluctuations? Gravitational lensing? Dwarf
galaxy velocity dispersions?

We have to get to the same level when looking for alien life. If you are
convinced that it doesn't exist, you will never find it.


I don't think anyone -- perhaps barring a few cranks -- is convinced
extraterrestrial life doesn't exist. There are active searches in
progress and more planned for the future. What priority to give
potential searches, in comparison to other projects competing for
funding, is a difficult judgment question.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA