Life on Mars

Question 1

What type of programme was the Mariner programme and what did it reveal?

Answer 1

• flyby probe

- revealed gigantic volcanoes, a gran canyon and relics of ancient riverbeds

Question 2

What 3 experiments did the Viking conduct to analyse soil samples on Mars for life?

Answer 2

1) Labelled release - Add nutrients with radioactively labelled carbon and see if there are any waste products (GAVE FALSE POSITIVE)
2) Gas exchange - add nutrients and see if biogenic gases are released
3) Pyrolytic release - add CO2 with radioactively labelled C and bake, see if any labelled C is released

Question 3

What are the flaws of the Viking mission?

Answer 3

• lack of understanding of the martian surface

- expectations of biology were fundamentally flawed

Question 4

What methods were adopted for Mars explorations 1997 onwards?

Answer 4

‘explore habitability’ and ‘follow the water’ - goal to understand the geology and chemistry of mars before looking for life

Question 5

What 2 methods can be used to investigate presence of past water on Mars?

Answer 5

1. Looking at rock records to look for clay and carbonate sedimentary deposits
2. Distribution of haematite (iron rust) which needs water to form

Question 6

What possibly explains the false positive result of the labelled release experiment?

Answer 6

Pheonix lander in water rich are found evidence of perchlorate which when heated forms CO2

Question 7

Describe psychrophiles. Where are they present on Earth, and how do they survive these environments?

Answer 7

Present in: sea ice, glaciers & permafrost (cold places basically)
Survive by: using slow metabolism & antifreeze proteins

Question 8

Describe halophiles. Where are they present on Earth, and how do they survive these environments? What do they require to grow?

Answer 8

Present in: soda lakes, salt flats, salt pans, subsurface brines (salty places basically)
Survive by: expelling sodium(Na) in exchange for hyrdogen(H)
Requires high levels of salt to grow.

Question 9

Describe acidophiles. Where are they present on Earth, and how do they survive these environments?

Answer 9

Present in: geothermal areas
Survive by: maintaining neutral pH levels by exchanging protons for cations (positively charged ions) OR by having a very thicc cell wall.