SpaceX launched the Crew Resupply Mission 28 (CRS-28) mission to the International Space Station (ISS) on June 5 at 11:47 PM EDT (15:47 UTC) from Launch Complex 39A (LC-39A) at the Kennedy Space Center in Florida.
CRS-28 – which docked on Tuesday – will resupply the ISS with equipment and supplies needed by Station astronauts and hardware for the coming months, as well as science experiments developed by different agencies, companies, and organizations from around the world. Furthermore, tucked away in Dragon’s trunk are two new iROSA solar panels for the Station.
As mentioned, in addition to CRS-28’s delivery of food and other hardware, a wide range of scientific payloads and science experiments will be launched to the Station on this mission.
Thor, a European Space Agency science project, will observe thunderstorms in Earth’s atmosphere from ~250 kilometers above the surface. Thor’s goal is to measure the frequency and altitude of blue discharges produced by internal phenomena and structures within thunderstorms.
CRS-28 is also carrying the Genes in Space-10 experiment, which is a student-designed DNA experiment that the ISS National Laboratory supports. The Genes in Space experiments allow students in grades seven through 12 to design DNA experiments that can withstand the challenges of space exploration and answer questions like “Can we detect new life forms?” and “Can living organisms help us colonize new worlds?” These experiments are then launched to the ISS where they are tested.
The first Genes in Space experiment, launched in 2016, researched the impact of microgravity on the human body, specifically the immune system, which has been found to be weakened by microgravity. For Genes in Space-10, the goal is to research a method that can be used to measure the length of DNA segments in space, which was proposed by 2022 winner Pristine Onuoha. Common Earth-based methods for measuring DNA segment lengths are already complex, and adding zero-gravity to the methods will only increase their complexity.
The NASA Plant Habitat — an experiment used to investigate plant growth in microgravity environments — will get some new seeds when CRS-28 arrives at the Station. The habitat aims to verify the adaptation of various plants to the environment of space and studies the specific ways plants learn to thrive in an environment with no gravity. Furthermore, the experiment aims to determine if humans can pre-adapt plants for prolonged spaceflights.
Another payload that launched onboard CRS-28 is the Moonlighter 3U cubesat, which was built by The Aerospace Corporation. Moonlighter will be the first hacking testbed in space, serving as a sandbox that will allow cyber security experts to perform tests and attempt to hack the cubesat’s software in space. The purpose of the cubesat is to research tactics for preventing satellite software and hardware hacking, with in-space assets like satellites becoming increasingly important to global infrastructures.
In addition to Moonlighter, the Canadian Space Agency will deploy five cubesats designed by students from the ISS. One cubesat from York University, named Essence, will observe arctic ice for climatic research purposes by using a camera with a fisheye lens. Essence will also carry a solar energetic proton detector to collect additional data from solar ejection events, which are brief periods of solar activity wherein the Sun emits radioactive protons into space. These solar ejection events can damage spacecraft, and understanding the ways in which these radioactive protons damage spacecraft will help future satellite designs to be more resistant to solar ejections.
Lastly, NanoRacks’ IRIS will observe the weathering of geological samples under cosmic radiation and direct solar radiation exposure. This could help geologists further understand the strength of Earth’s surface and the forces that satellites endure when flying in space.
iROSA Solar Arrays
The Station will get two new ISS Roll Out Solar Arrays (iROSA) on CRS-28, which are expected to help improve the Station’s overall power availability. The solar arrays are significantly smaller and lighter than the arrays first installed on the ISS during its initial construction, with iROSAs having the ability to be rolled up during launch. Following Cargo Dragon’s docking to the ISS, one of the Station’s robotic arms will remove the arrays, which will then be installed during a spacewalk. Once installed, the arrays will roll out of their spool and fully deploy.
CRS-28 is part of three missions to launch and deploy iROSAs on the ISS. Each of the launches requires two spacewalks to install the arrays, with the first set of arrays being launched in November 2022 and installed the following month. One spacewalk prepares the area for the installation, and the second spacewalk installs the iROSA to the Station. Each new array produces more than 20 kilowatts of electricity, bringing the performance of all six new iROSA panels, when installed on the ISS, to 120 kilowatts.
Falcon 9’s Countdown and Launch
Days before the launch of CRS-28, Falcon 9 rolled out to LC-39A horizontally and rotated to the vertical position once on the launch mount. The main part of the countdown started at the T-35 minute mark when fueling of Falcon 9 began. During fueling, Falcon 9 was loaded with RP-1 kerosene and liquid oxygen (LOX).
Later in the countdown, at T-20 minutes, RP-1 loading on Falcon 9’s second stage was completed, signified by the iconic T-20 minute vent, which is caused by the purging of Falcon 9’s fuel lines in preparation for LOX loading on the second stage. At T-1 minute, Falcon 9 entered startup, when Falcon 9’s onboard computer took over the countdown and manages the final seconds of the countdown ahead of liftoff.
At T0, Falcon 9 will lifted off under the power of the nine Merlin 1D engines on the first stage. Following maximum aerodynamic pressure, or the period of ascent where aerodynamic loads are greatest on the vehicle, the first stage engines shut down, and the first and second stages separated. The Merlin vacuum-optimized engine on the second stage continued to loft Cargo Dragon into orbit.
CRS-28 featured the updated shorter nozzle on the Merlin vacuum-optimized engine on the second stage, which helps reduce manufacturing time, thus improving launch cadence. Furthermore, the shorter nozzle means that less metal needs to be used during manufacturing, which, in turn, reduces construction costs and increases the number of Falcon second stages that can be created. This shorter nozzle has slightly lower performance than its larger counterpart, which is compensated by this mission not needing increased performance from Falcon 9.
Correction! This is for CRS-28! https://t.co/DuGAv3PrJf
— Gav Cornwell (@SpaceOffshore) May 31, 2023
Following stage separation, B1077 landed on SpaceX’s autonomous spaceport droneship A Shortfall of Gravitas, stationed in the Atlantic Ocean. Following landing, the booster officially changed from B1077-5 to B1077-6 and began to prepare for its next flight in a few months. B1077 has supported Crew-5, a GPS mission, the Inmarsat mission, and one Starlink flight.
With CRS-28 arriving at the Station, the Soyuz MS-23 crew and the Crew-6 crew will conduct the aforementioned science experiments. The MS-23 crew consists of Oleg Kononenko, Nikolai Chub, and Loral O´Hara. The Crew-6 crew consists of Stephen Bowen, Warren Hoburg, Sultan Al Neyadi, and Andrey Fedyaev
(Lead image: CRS-28’s Cargo Dragon, C208, launches atop Falcon 9 on LC-39A. Credit: Max Evans for NSF)