In the late 1960s and 70s, José (Michael Peña) is a young boy whose family (Father Salvador Hernandez (Julio Cesar Cedillo), Brother Beto, mother Julia (Verónica Falcón) and sister Lety) travels from Michoacán as migrant workers picking grapes in California, his parents hoping to buy a house back home after they've made enough money. While they are working in the harvest season, José attends school and works in the fields with his family after. His teacher, Ms. Young (Michelle Krusiec), notices his potential and visits his parents at home to express her concern over the disruption to his studies by going back and forth as migrant workers. Jose says that he wants to be an astronaut after he watches he 1969 moon landings on TV. After his father is only paid partial wages for his work, he realizes José's teacher was right to be concerned and the family decides to stay in California full time.Years later in 1985, José graduates from the University of the Pacific and is hired as an engineer at the Lawrence Livermore National Laboratory. The lab is working on the most sophisticated laser weapon in the world to protect the USA from incoming ballistic nuclear missiles.Salvador never stops reminding Jose how much the whole family has sacrificed for him. Jose has to bear racial stereotyping at work when he is assumed to be the new janitor by the lab staff. Beto still works in the fields. He is then given menial tasks such as photocopying thousands of documents. Weissberg (Jordan Dean) is Jose's colleague. Jose has already started applying to NASA and his application has been rejected.Feeling as if he needs to fit in better, he trades in his customized 1963 Chevrolet Impala for a used Mazda RX-7. While signing the paperwork for the new car, he meets Adela (Rosa Salazar), whom he asks out. After an intimidating first meeting with her family (Adela has a large family and her father insists that he would have to be present for all visits), they see each other more until they marry. They have five kids. Adela laughs at Jose's goal of wanting to be an astronaut. Jose finds major flaw in the laser design while photocopying the documents. He brings it to the notice of his supervisor that the Beryllium detector in the laser cannot differentiate between the heat from the laser and the heat from an explosion, hence giving spurious readings. José continues to work successfully at the lab, now instructing the researchers, including Weissberg, who had previously ignored him.By now Jose has been rejected by NASA 6 times. Adela realizes that Jose is serious about his astronaut dream. She wants him to do what it takes to get selected. Jose says that the last batch of astronauts had 12,962 applicants. The selected batch had many pilots, & high-performance athletes. Jose trains himself to be a pilot and works on his fitness. He starts diving training, as one of selected had logged more than 700 dives. Many of them speak Russian. After several years Jose is able to gain proficiency in many of the skills needed for the program.One day during class, José's boss Clint Logan (Eric Johnson) offers him a chance to join a team going to Russia to evaluate a shipment of enriched uranium the United States is looking to purchase for NASA, noting that a trip like that would look really good on an application to the NASA space program. In 1999, Jose travels to Russia and stays there for 6 months. After several rejections, José hand delivers his 12th application in person to Frederick Sturckow (Garret Dillahunt) who trains incoming astronauts and is a veteran of the Space Shuttle program. He makes a positive impression on Sturckow and is accepted into the program shortly thereafter.José struggles with the training, falling further behind the rest of his class. When he learns of Beto's (Bobby Soto) death in a gang-based shoot-out, he loses focus and is exhorted by Sturckow to catch up with the rest or he may be dismissed from the program. He later has a conversation with the head trainer, Kalpana Chawla (Sarayu Blue), who describes to him why going to space makes all of their hard work worthwhile, and ends by letting him know she's been selected as the Mission Specialist for STS-107 on Space Shuttle Columbia.As José sits with his family watching the broadcast of Columbia's re-entry, they are shaken when news comes in that Columbia didn't survive. Nevertheless, José continues on and begins excelling among his classmates at NASA. Jose hires a commercial property as location for Adela's Mexican restaurant.In 2008, Sturckow pulls José into a conference room to meet with the selection team, who informs him that he's been chosen to join STS-128 as their Mission Specialist. José visits Adela's restaurant outside the NASA grounds and tells her the news, with his family later watching him at the press conference. He quotes Beto's words to him that it's fitting for a migrant farm-worker to go into the unknowns of space. As he enters quarantine in preparation for the mission, Adela visits him with a surprise: his former teacher Ms. Young, who tells him she's been waiting for this moment for over 30 years, having followed his progress and career, always believing in his enormous potential.The launch day finally arrives, José is prepared along with the rest of the crew who board the shuttle and launch into orbit. After main engine cutoff, José looks around at the shuttle cabin and imagines seeing the same Monarch Butterfly that landed on his dad's arm the day their family decided to stay in California, hinting that he had achieved his destiny.Closing titles note that Mission STS 128 remained on board the International Space Station for 13 days, and that José had tacos and listened to José Alfredo Jiménez's "El Hijo Del Pueblo" while there. José was the first migrant farm-worker in space, and still picks grapes with his father today, albeit in his own vineyard: Tierra Luna Cellars in Lodi, California.