(CNN) It's called rocket science for a reason.
When NASA Deputy Administrator Pam Melroy was preparing for one of her space shuttle launches as an astronaut in the early 2000s, she told her relatives to plan a week's trip to Florida for vacation and they might see a launch.
Members of the Artemis I mission team gave their families the same advice -- and it's because a multitude of factors need to go just right for a successful space launch.
The launch team made the decision to postpone Artemis I's liftoff on Monday when weather delays and mechanical issues cropped up during the countdown.
A second launch attempt was scheduled for Saturday afternoon, but that has also been scrubbed.
A troublesome liquid hydrogen leak is the cause of the second scrub for Artemis I.
Liquid hydrogen is one of the propellants used in the rocket's large core stage. The leak prevented the launch team from being able to fill the liquid hydrogen tank despite multiple attempts at troubleshooting.
NASA is expected to share an update at 4 p.m. ET Saturday.
NASA administrator Bill Nelson said that the mission managers will hold a meeting to discuss the next steps and determine if a launch is possible on Monday or Tuesday, or if the rocket stack needs to be rolled back into the Vehicle Assembly Building. If it is rolled back into the building, a launch may not be possible until mid-October.
Archaeologists have cracked open a medieval mystery using ancient DNA.
The remains of six adults and 11 children found by builders at the bottom of an 800-year-old well shaft in Norwich, England, have been identified as victims of antisemitic violence.
The genomes of six of the individuals showed that four of them were related -- including three sisters, the youngest of whom was 5 to 10 years old. Further analysis of the genetic material suggested all six were Ashkenazi Jews and allowed the researchers to infer the physical traits of a toddler found in the well.
The researchers said the discovery shined a light on the "real horror" of what persecuted Jewish communities experienced.
An encounter with the deep past of our planet can happen just about anywhere.
One Portuguese property owner came across fragments of fossilized dinosaur in his backyard, when construction work revealed the chest bones of a towering sauropod -- a long-necked, plodding plant eater.
Paleontologists believe the dinosaur was around 39 feet (12 meters) high and 82 feet (25 meters) long.
Steve Brusatte, a professor of paleontology at the University of Edinburgh in Scotland not involved in researching the specimen, called the discovery "gobsmacking -- a dinosaur rib cage sticking out of somebody's garden."
Unlike Earth, Mars has no oxygen-generating forests. However, engineers at NASA and the Massachusetts Institute of Technology have tested a mechanical tree with the potential to make the red planet more hospitable for astronauts.
The Mars Oxygen In-Situ Resource Utilization Experiment -- better known as MOXIE -- has been successfully making oxygen from Mars' carbon dioxide-rich atmosphere as part of NASA's Perseverance rover mission.
The toaster-size tech demo has produced oxygen on seven experimental runs since April 2021 in a variety of atmospheric conditions.
In each run, MOXIE reached its target of producing 6 grams of oxygen per hour -- about the rate of a modest tree on Earth. Researchers hope a scaled-up version will produce enough oxygen to sustain humans on Mars and fuel a rocket for returning astronauts to Earth.
The Great Pyramid of Giza was the tallest building in the world for some 4,000 years.
It's still a mystery how this monumental feat of ancient engineering came together, but a new study confirms a long-held theory that the pyramid builders took advantage of a now lost arm of the Nile River to move construction materials.
Researchers studied plant pollen preserved in cores of earth to identify vegetation-rich areas that indicated high water levels and create models of what the waterscape around the pyramids looked like over the past 8,000 years. The data revealed that the Khufu branch of the Nile had high water levels during the construction of the three main pyramids, which could have enabled ancient builders to develop an unusual system of moving materials by boat.
By the time Alexander the Great conquered Egypt in 332 BC, however, environmental factors had reduced the Khufu branch to a tiny channel, the study found.
Escape for a moment with these extraordinary stories:
-- A snow-covered stag and a tree frog pool party are some of the striking entries in the Wildlife Photographer of the Year 2022 competition.
-- The genetic code of the so-called immortal jellyfish could unlock the secret to reversing aging.
-- The James Webb Telescope is on a roll. Check out its first direct image of a gas giant exoplanet as well as a spellbinding view of the Phantom Galaxy.