Phoenix has been having trouble getting soil into its ovens
Nasa's Phoenix spacecraft will try a new way of getting icy Martian soil into its onboard oven for testing, after it ran into problems last week.
The soil has proven to be very sticky, hampering attempts to carry out tests.
On its previous attempt, most of the soil sample collected by Phoenix's robotic arm got stuck in the scoop and would not fall into the oven.
Controllers will now try a different strategy which involves less drilling and more shaking of the scoop.
Phoenix touched down successfully on Mars' northern plains on 25 May (GMT).
"We are going to modify the process we ran on Sol 60 to acquire another icy sample and attempt to deliver it to TEGA [the Thermal and Evolved-Gas Analyzer instrument]", said Barry Goldstein, the mission's project manager.
Mr Goldstein, from Nasa's Jet Propulsion Laboratory in California, added: "We will repeat what we did successfully with small modifications to adjust for what we learned."
The TEGA ovens will bake and sniff the soil to assess its volatile chemical ingredients, such as water. This could give scientists clues to whether Mars was ever capable of supporting life.
On 26 July, Phoenix successfully obtained a sample of ice and soil by drilling 16 holes into the work trench informally named "Snow White" with the motorised "rasp" on the end of its robotic arm.
It then picked up the sample with its scoop, but most of the sticky Martian soil adhered to the scoop even after it was tipped and the rasp activated to help sprinkle soil into the oven for baking and analysis by TEGA.
The revised plan involves cutting the amount of time spent using the rasp, to avoid heating the sample, and shaking the scoop more when delivering it to the oven.
Images received by mission control on Sunday morning showed the soil collected during the previous attempt has now fallen out of the scoop.