(CNN) NASA astronaut Christina Koch made the most of her first trip to the International Space Station by breaking the record for the longest single spaceflight by a woman and conducting the first all-female spacewalk with fellow NASA astronaut Jessica Meir.

"We caught each other's eye and we knew that we were really honored with this opportunity to inspire so many, and just hearing our voices talk to Mission Control, knowing two female voices had never been on the loops, solving those problems together outside -- it was a really special feeling," Koch said of that first spacewalk, on October 18.

Koch returned to Earth early Thursday along with European Space Agency astronaut Luca Parmitano and Russian cosmonaut Alexander Skvortsov. The Soyuz spacecraft carrying the astronauts landed near Zhezkazgan, Kazakhstan at 4:12 a.m. ET.

During her mission, Koch completed six spacewalks -- including another two with Meir -- and spent 42 hours and 15 minutes outside of the station.

Koch also devoted much of her time to a variety of experiments and investigations. The space station acts as an orbiting laboratory that can be used to test how different aspects of everyday human life on Earth react to the lack of gravity.

On the station, astronauts experience a plethora of science activities. Sometimes, they're the test subject, contributing to studies about human health in space. Other times, they're working with scientists on Earth to test their experiments.

In addition to her firsts and records, here's what Koch accomplished over 328 days in space along with some of her favorite moments.

Koch returned to Earth on Thursday.

Human health

Just by extending her original six-month mission and reaching this record of 328 days, Koch has contributed to a better understanding of what long-term spaceflight can do to the human body. It surpassed astronaut Peggy Whitson's previous record of 288 days. NASA astronaut Scott Kelly still holds the all-time record with 340 days in space.

The lack of gravity in space causes bone and muscle loss in astronauts, so a multitude of studies past and present have focused on how to mitigate and even prevent this from happening. Koch was part of the Vertebral Strength investigation, which focused on helping develop countermeasures to the impact of spaceflight, like preventative medicine and exercise. What they learn from the investigation could also help NASA place a limit on the forces astronauts face during launch.

Koch and Meir prepare for their first spacewalk.

The Kidney Cells investigation was another way of studying potential human health issues that could occur in space: Kidney stones and osteoporosis, which can happen due to bad kidney health. One aspect of the study focused on the effects of diet, water conservation, space travel and microgravity on kidney health. The other aspect is trying to determine new treatments for kidney stones and osteoporosis.

Koch also worked on the Microgravity Crystals investigation, where she crystallized a protein that's key for the growth of tumors and cancer. While similar experiments on Earth haven't provided the desired result, crystal growth has been successful in previous space station experiments. In microgravity, crystals grow larger and appear more organized. The findings from this study could lead to cancer treatments that can efficiently target the protein.

Looking ahead to future missions, Koch helped install the BioFabrication Facility , which can print organ-like tissues in space. This could lead to actually producing whole human organs beyond Earth's horizons in space. While its difficult for structures like capillaries to be printed on Earth, these structures form much easier in the absence of gravity.

Weird science

What do leafy greens, atoms and fire all have in common? They've all been tested in unique ways on the space station that aren't possible on Earth.

Koch is pictured with mustard greens being grown and eaten on the space station.

Koch was involved in multiple studies of plant biology, from the cellular level to studying how plants grow in space. She and the crew were able to taste test fresh Mizuna mustard greens grown on the station, which could lead to more fresh food for future spaceflight. More of the greens were frozen so they can be studied on Earth.

Multiple investigations aim to understand the way fire reacts and behaves in space, which can provide insight about preventing fires on spacecraft, as well as the efficient use of fuel and reducing pollutants on Earth. Koch worked on some of these studies using the Advanced Combustion via Microgravity Experiments Chamber.

The opposite of the combustion chamber must be the Cold Atom Laboratory , where atom clouds are created and then chilled to the tiniest degree above absolute zero. The cold temperature keeps the atoms from moving, and scientists are then able to study aspects of atoms that wouldn't be possible otherwise. Koch was also involved with this hardware.

Koch with the Cold Atom Lab hardware.

Memorable moments

Koch arrived at the space station on March 14, 2019. She was the first to go through the hatch.

"That was the day that I have seared in my memory," she said. "Visions from when I first arrived here ... I'm very privileged to have that as one of my favorite memories."

She treasures moments that connected her with home -- like the time she realized they were passing over coastal North Carolina, where she grew up. And then there were the care packages from home that included pizza kits to break the monotony of the meals they eat on the station.

I'm going to miss this bunch. Thank you, space family. #Expedition61 pic.twitter.com/pteShj231d — Christina H Koch (@Astro_Christina) February 5, 2020

Over time, Koch actually forgot she was floating. She adjusted to microgravity so well that she's wondering how she'll readjust to Earth's gravity.

"Sleep in space has been some of the most restful I've ever had -- no hotspots, no tossing, no turning, never too hot or too cold. I just float in my body's natural position. How will I sleep when I return to Earth?"

But Koch is also looking forward to the things she's missed about Earth, like the sensation of running water, food, sweet smells and the sensations afforded by nature.

"Oh, how I miss the wind on my face, the feeling of raindrops, sand on my feet and the sound of the surf crashing on the Galveston beach," she said. "We take daily sensory inputs for granted until they are absent. The environmental inputs on the space station consist mostly of the constant hum of the ventilation system. It stirs the air, allowing the purification system to scrub and clean our atmosphere so it's breathable. While some places on the space station are as loud as a lawn mower, others are as quiet as the vacuum of space. I cannot wait to feel and hear Earth again."

For 300 days I've been fortunate to be a part of something that strives to represent and benefit all humanity. As I look out and reflect on our shared world, that has been the greatest honor. pic.twitter.com/uQuS5F4rXj — Christina H Koch (@Astro_Christina) January 9, 2020

Like other astronauts before her, photographing Earth and regarding it during her spacewalks has given her a new appreciation for her home.

"Earth is alive, and I have witnessed its power and beauty from a special vantage point 250 miles above the surface," she said. "From the space station we see no borders, no boundaries -- we are all part of one giant organism that breathes and adapts. I have been in awe of this perspective for almost a year now. Back on Earth I anticipate looking up and seeing the space station streak across the sky, wondering how my friends and colleagues are doing up there without me. For almost 20 years humans have continuously lived and worked in space and the mission continues."