A SpaceX Dragon capsule lifted off for a resupply run to the International Space Station (ISS) on June 5, carrying more than 7,200 lb. of cargo including another pair of next-generation solar arrays to upgrade the 22-year-old outpost’s electrical power system.
The Commercial Resupply Mission-28, also known as SpX-28, began with an 11:47 a.m. EDT launch aboard a Falcon 9 rocket from the Kennedy Space Center’s Launch Complex 39A. Two min., 34 sec. later, the reusable first stage separated from the upper stage and Dragon spacecraft, then headed to a drone ship stationed off Charleston, South Carolina, for its fifth landing.
Meanwhile, the upper stage’s single Merlin vacuum engine fired to boost the spacecraft into a preliminary orbit.
Anchored inside the spacecraft’s unpressurized trunk are a pair of ISS Roll Out Solar Arrays (iROSA), manufactured by Redwire under contract with Boeing. They are to be installed over the station’s existing solar array wings. Once unfurled, the new lightweight arrays, which measure 63 X 20 ft., will cover about half the length and width of the original arrays, but generate about as much power.
The iROSAs launched on June 5 are the third and final set of arrays to be installed as part of a two-year upgrade to the station’s solar power-generation system. Station flight engineers Steve Bowen and Woody Hoburg are due to conduct spacewalks on June 9 and 15 to position the iROSAs on the station’s starboard truss.
Eight legacy panels were installed on the port and starboard sides of the 360-ft. solar power truss during NASA space shuttle assembly missions between November 2000 and March 2009. Once extended, each of the iROSAs is designed to generate 20 kW of electricity, boosting power generation overall by 30% to support the crew and some 300 science experiments and research activities.
If funds are available, NASA may add a fourth pair of iROSAs as demand for power is expected to continue to grow with the addition of the commercial Axiom Station, which is slated to be built onto the ISS beginning in late 2025.
In addition to the new solar arrays, SpaceX’s 28th cargo run for NASA will deliver food, supplies and science experiments. They include:
•Thor-Davis is an investigation from the European Space Agency that is expected to observe thunderstorms from the space station. From this vantage point, researchers will be able to study the origin, frequency and altitude of recently discovered blue discharges. Scientists plan to estimate the energy of these phenomena to determine their effect on the atmosphere. A better understanding of lightning and electrical activity in Earth’s atmosphere could improve atmospheric models and provide a better understanding of Earth’s climate and weather.
•Plant Habitat-03 is expected to assess whether plants grown in space can transfer adaptations made in response to the environmental stresses of space to the next generation and, if so, whether a change continues through subsequent generations or stabilizes. The results could provide insight into how to grow multiple generations of plants to provide food and other services on space missions, as well as support development of strategies for adapting crops and other economically important plants to marginal and reclaimed habitats on Earth.
•Genes in Space-10 is designed to test a technique for measuring the length of protective genetic structures known as telomeres, which are known to shorten with age and wear. Research has shown telomeres actually lengthen in space. The experiment will explore whether telomere lengthening is caused by the proliferation of stem cells—undifferentiated cells that give rise to specific body components and that typically have long telomeres. Results also could lay the groundwork for related research to help long-duration space travelers as well as people on Earth.
•Iris, sponsored by the ISS National Laboratory, is due to observe the weathering effects of solar and cosmic radiation on 20 geological samples. Iris also will demonstrate experimental Sun sensors, torque rods and a battery heater.
•Clingers, developed by the University of Southern California’s Space Engineering Research Center, is scheduled to demonstrate autonomous docking system technologies. The research could lead to applications such as in-orbit satellite servicing, orbital refueling and in-orbit manufacturing processes.
