context: Unbeknownst to humans, there is a thriving, technologically sophisticated society of Martians living below the surface of Mars. The Martians Supervisor (Mindy Sterling), while observing Earth, sees a mother (Joan Cusack) persuading her son, Milo (motion by Seth Green, voice by Seth Dusky), to do his chores. The Martians decide to bring her to Mars, where her "momness" will be extracted and implanted into the next generation of nannybots. Meanwhile, Milo, who doesn't like following the house rules and doing chores, tells his mother in anger that his life would be better without her, breaking her heart.
  Later that night, Milo goes to apologise, but discovers his mom is being abducted. He runs after her, but they end up in separate parts of the Martian spaceship. On Mars, Milo is taken to an underground cell. He escapes and is chased by Martian guards, but he follows a voice that tells him to jump down a chute, and lands in a lower subterranean level. There, he sees a trash-covered landscape that is inhabited by furry creatures.
  Milo is whisked away by the creatures to meet Gribble, a.k.a. George Ribble (Dan Fogler), the childlike adult human who had told him to jump down the chute. Gribble explains to Milo that the Martians plan to extract Milo's Mom's memories at sunrise, using a process that will kill her. Gribble, who is lonely and doesn't want Milo to leave, pretends to help Milo rescue his mother, but his plan goes awry leading to Gribble being captured and Milo being pursued by Martian guards.
  Milo is rescued by Ki (Elisabeth Harnois), one of the supervisions who raises Martian babies. Milo tells her about his search for his Mom and what a human relationship with a mom is like, as Ki and her kin were mentored by only nannybots and supervisors and don't know of love.
  Milo returns to Gribble's home but finds him missing. Gribble's robotic spider, Two-Cat (Dee Bradley Baker), takes Milo to the Martian compound where Gribble is being prepared for execution. Milo is captured by the guards, but Ki tosses him a laser gun, allowing him to escape.
  Milo and Gribble retreat to an even lower uninhabited level, where, Gribble explains his Mom's abduction and murder by the Martians 25 years earlier. Gribble blames himself for her being chosen, and regrets that he hadn't been able to save her. Milo convinces Gribble to actually help him just as Ki finds them. They discover an ancient mural of a Martian family and realize that Martian children weren't always raised by machines. Gribble explains that Martian female babies are currently raised by nannybots in the technologically advanced society, while the male babies are sent down below to be raised by adult male Martians, which are the furry creatures he encountered earlier.
  Milo, Gribble, and Ki save Milo's Mom just before sunrise, causing the energy of the extraction device to short out the electronic locks to the control room. This lets the adult males and babies enter, where they run amok, attacking the guards and robots.
  Milo and his Mom steal oxygen helmets and try to escape across the Martian surface, but the Supervisor causes Milo to trip and his helmet shatters. His Mom gives him her own helmet, saving Milo but sacrificing herself. The Martians are awed, as this is the first time they have seen love.
  Gribble finds his own mother's helmet, and gives it Milo's Mom, saving her. Ki brings a ship for them to escape in, but the Supervisor intervenes. Ki argues that Martians were meant to be raised in families, with love, but the Supervisor insists that the current situation is better, because it is more efficient. The guards decide to arrest the Supervisor because they prefer the loving vision of family-life. The other Martians celebrate.
  Milo, his Mom, Gribble, Ki, and Two-Cat travel to Earth. Gribble decides not to stay, because he wants to pursue a relationship with Ki on Mars. Milo and his Mom return to their house just before Milo's Dad (Tom Everett Scott) comes home.
question: Who lands outside Milo's house ?
answer: The Martians