A Ridiculously Huge Pair of Ancient Galaxies

Astronomers have discovered a pair of massive galaxies from the early universe, challenging existing models of galaxy formation. These galaxies, observed using gravitational lensing, are embedded in significant amounts of dark matter. Meanwhile, NASA's Opportunity Rover has survived its eighth Martian winter, despite challenges like dust storms and limited sunlight. The rover's resilience highlights the unpredictability and challenges of space exploration.

What is the estimated mass of dark matter surrounding the newly discovered galaxies?

What factors contribute to the difficulty of the Opportunity Rover in capturing sunlight?