Phoenix to land using retros?

Seems like Phoenix is to soft land using retros. Is that wise?
Mightn't they frazzle some or all the evidence for life being sought?
I'd have thought airbags would have been better in this case.

Matt

Cruithne3753 wrote in
:

Seems like Phoenix is to soft land using retros. Is that wise?
Mightn't they frazzle some or all the evidence for life being sought?
I'd have thought airbags would have been better in this case.

It appears the strategy is that the mission will have to
dig for subsurfact evidence of biology, that the surface
conditions are too severe. A few inches of soil should
protect that evidence.

I'm waiting for the big rover, that can travel to various
sites and chose likely spots to explore in detail. Maybe
collect interesting tidbits for a sample return mission.

--Damon

On Aug 4, 9:43 am, Cruithne3753
wrote:
Seems like Phoenix is to soft land using retros. Is that wise?
Mightn't they frazzle some or all the evidence for life being sought?
I'd have thought airbags would have been better in this case.

Matt

It's called a controlled (one-way) hard landing, and it's still after
4 decades and counting the very best we can manage in spite of
whatever our hocus-pocus NASA/Apollo wizards supposedly accomplished.
- Brad Guth

On Aug 4, 10:54 pm, Damon Hill wrote:
Cruithne3753 wrote . uk:

Seems like Phoenix is to soft land using retros. Is that wise?
Mightn't they frazzle some or all the evidence for life being sought?
I'd have thought airbags would have been better in this case.

It appears the strategy is that the mission will have to
dig for subsurfact evidence of biology, that the surface
conditions are too severe. A few inches of soil should
protect that evidence.

I'm waiting for the big rover, that can travel to various
sites and chose likely spots to explore in detail. Maybe
collect interesting tidbits for a sample return mission.

--Damon

If it survives their retro rocket controlled hard landing, a few feet
(not inches) underground should be signs of whatever microbe life.
Remember, it's going to bounce at least once upon arriving, that is
unless sinking meters deep into a fluffy pile of CO2 snow.
- Brad Guth

In article ,
Cruithne3753 wrote:
Seems like Phoenix is to soft land using retros. Is that wise?
Mightn't they frazzle some or all the evidence for life being sought?

It's a concern, although the top few millimeters are almost certainly
sterile even if there is life farther down.

I'd have thought airbags would have been better in this case.

Unfortunately, airbag systems are quite heavy and hence have very limited
payloads, are usable only in limited areas of Mars (because they need
relatively thick air for their braking parachutes, and hence can land only
at low-altitude sites), and are quite sensitive to wind. The airbag
landing system for the MERs was complex and tricky, and everyone was
immensely relieved when it actually worked twice in a row. This is why
the general trend is back to rocket landing.

In this particular case, the designers had no choice, because they weren't
starting from scratch -- they could fly this mission relatively cheaply
only by using much of the hardware built for the canceled 2001 lander.
(The 2001 lander was to use the same spacecraft bus as Mars Polar Lander,
although with a different payload and some other minor changes. It was
canceled, with the spacecraft almost complete, after the MPL failure.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

On Mon, 6 Aug 2007 17:15:22 GMT, in a place far, far away,
(Henry Spencer) made the phosphor on my monitor
glow in such a way as to indicate that:

In article ,
Cruithne3753 wrote:
Seems like Phoenix is to soft land using retros. Is that wise?
Mightn't they frazzle some or all the evidence for life being sought?

It's a concern, although the top few millimeters are almost certainly
sterile even if there is life farther down.

I'd have thought airbags would have been better in this case.

Unfortunately, airbag systems are quite heavy and hence have very limited
payloads,

One of the reasons that it's rumored that NASA is pulling them out of
Orion and going back to water landings. Just like the good old
days...

On Aug 5, 7:06 am, BradGuth wrote:
On Aug 4, 10:54 pm, Damon Hill wrote:





Cruithne3753 wrote . uk:

Seems like Phoenix is to soft land using retros. Is that wise?
Mightn't they frazzle some or all the evidence for life being sought?
I'd have thought airbags would have been better in this case.

It appears the strategy is that the mission will have to
dig for subsurfact evidence of biology, that the surface
conditions are too severe. A few inches of soil should
protect that evidence.

I'm waiting for the big rover, that can travel to various
sites and chose likely spots to explore in detail. Maybe
collect interesting tidbits for a sample return mission.

--Damon

If it survives their retro rocket controlled hard landing, a few feet
(not inches) underground should be signs of whatever microbe life.
Remember, it's going to bounce at least once upon arriving, that is
unless sinking meters deep into a fluffy pile of CO2 snow.
- Brad Guth- Hide quoted text -

- Show quoted text -

On Aug 6, 11:28 am, BradGuth wrote:
On Aug 5, 2:13 pm, John wrote:



On Aug 5, 11:04 am, BradGuth wrote:

On Aug 5, 5:18 am, John wrote:

Sorry that I missed a chance to watch it . . . I know . . . I
know . . . its (just) another Delta, but I will never tire of watching
launchs. If I were still living in Florida, I think I would be
watching each one by stepping outside . . . even if they were
everyday.

This is a quote from an AP story about the Phoenix launch to Mars on
Saturday:

"If all goes as planned - a big if considering only five of the
world's 15 attempts to land on Mars have succeeded - the spacecraft
will set down on the Martian Arctic plains on May 25, 2008

I count Vikings 1 and 2, Sojourner, Opportunity and Spirit as
successful landings which is five. While I know there have been a
number of failures, have there really been no other successful
landings on Mars?

take care . . .

John

9+ months of travel, of years taken before launch, of billions spent
and there's perhaps at best a 25% chance of that retro rocket assisted
landing doing its thing exactly as planned.

But to further think about it: How many honest retro rocket soft
landings have there actually been? (if any, as bouncing doesn't
count)
- Brad Guth- Hide quoted text -

- Show quoted text -

Viking 1 and 2 were rocket powered soft landings on Mars

I believe that makes the odds all of 3:1, or isn't it actually 2:1 ?

Either the third time is a total bust, or it's adding to that long
list of all previous retro rocket "soft" landings that supposedly
didn't bounce.

Are you absolutely certain that either "Viking 1 and 2" didn't
actually bounce their way onto that Martian deck? (aka one-way hard-
landing)

What exactly do you consider a fly-by-rocket controlled "soft
landing"? (perhaps one that you can dig yourself out and walk away
from?)
- Brad Guth

On Aug 5, 7:06 am, BradGuth wrote:
On Aug 4, 10:54 pm, Damon Hill wrote:





Cruithne3753 wrote . uk:

Seems like Phoenix is to soft land using retros. Is that wise?
Mightn't they frazzle some or all the evidence for life being sought?
I'd have thought airbags would have been better in this case.

It appears the strategy is that the mission will have to
dig for subsurfact evidence of biology, that the surface
conditions are too severe. A few inches of soil should
protect that evidence.

I'm waiting for the big rover, that can travel to various
sites and chose likely spots to explore in detail. Maybe
collect interesting tidbits for a sample return mission.

--Damon

If it survives their retro rocket controlled hard landing, a few feet
(not inches) underground should be signs of whatever microbe life.
Remember, it's going to bounce at least once upon arriving, that is
unless sinking meters deep into a fluffy pile of CO2 snow.
- Brad Guth- Hide quoted text -

- Show quoted text -

On Aug 6, 11:36 am, BradGuth wrote:
On Aug 6, 8:17 am, (Henry Spencer) wrote:





In article om,

John wrote:
I count Vikings 1 and 2, Sojourner, Opportunity and Spirit as
successful landings which is five...

Nitpick: landing #3 was Mars Pathfinder. For the landing, Sojourner was
just a passenger. :-)

While I know there have been a
number of failures, have there really been no other successful
landings on Mars?

That really is the full list. Some known failures, some that may have
actually *landed* successfully but were not heard from to confirm it, and
one borderline case (Russia's Mars 3) where either the lander or the
radio-relay system on the orbiter failed less than a minute after an
apparently-successful touchdown.

If you count only the US, the story isn't quite as bad -- five successes
out of eight attempts, counting the two Deep Space 2 penetrators as
separate attempts (they were passengers on Mars Polar Lander until just
before atmospheric entry, but were *probably* independent failures). You
might want to call that two failures rather than three, since the DS2s
most likely both failed for the same reason, whatever it was.

Those were not purely fly-by-rocket soft landers, more like a retro
controlled hard-landing, plus their having to survive a few pesky
bounce considerations that were anything but human rated unless your
bouncy arrival could be deployed as within a solid block of ice that
would bust open upon impact.
- Brad Guth

"Rand Simberg" wrote in message
...
On Mon, 6 Aug 2007 17:15:22 GMT, in a place far, far away,
(Henry Spencer) made the phosphor on my monitor
Unfortunately, airbag systems are quite heavy and hence have very limited
payloads,

One of the reasons that it's rumored that NASA is pulling them out of
Orion and going back to water landings. Just like the good old
days...

That's what it says he
http://www.nasaspaceflight.com/content/?cid=5187

Nothing like trading increased operational costs for a reduction in
development cost and weight. This really is Apollo on steroids. :-P

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

On Mon, 6 Aug 2007 17:59:54 -0400, in a place far, far away, "Jeff
Findley" made the phosphor on my monitor
glow in such a way as to indicate that:

One of the reasons that it's rumored that NASA is pulling them out of
Orion and going back to water landings. Just like the good old
days...

That's what it says he
http://www.nasaspaceflight.com/content/?cid=5187

Nothing like trading increased operational costs for a reduction in
development cost and weight. This really is Apollo on steroids. :-P

Not to mention Shuttle...

I discuss here, with additional contributor comments:

http://www.transterrestrial.com/arch...04.html#009504

But note that PAO is deniying it. For whatever that's worth.