The Celeste Chronicles

Imagine two identical twins. One stays home, living an ordinary life. The other leaves for a long trip and comes back... slightly younger than their sibling. It sounds like science fiction. But it's real, and it happened. When astronaut Scott Kelly spent nearly a year aboard the International Space Station while his identical twin brother Mark stayed on Earth, Scott returned having aged a tiny fraction of a second less. The reason isn't magic — it's physics. Einstein's theory of relativity tells us that time itself moves slightly slower for objects travelling at high speeds or experiencing different gravity. The ISS orbits Earth at about 28,000 km/h, fast enough for this effect, called time dilation, to actually be measured. The difference is tiny. A fraction of a second over months in orbit. But GPS satellites feel it too, and at a scale that matters. They orbit high above Earth, where gravity is weaker, causing their onboard clocks to run faster than clocks on the gro...

Spacecraft depend on a reliable supply of electrical power to operate almost every system onboard, from communication equipment, sensors and cameras to computers, navigation systems and scientific instruments. Unlike systems on Earth, spacecraft cannot simply connect to an external power source or refuel whenever energy is needed. This is why solar photovoltaic systems are the primary power source for many satellites and spacecraft. Solar cells convert sunlight directly into electrical energy through the photovoltaic effect, while batteries store excess energy for periods when sunlight is unavailable. The basic energy pathway is solar radiation → photovoltaic cell → electrical power → spacecraft systems . However, generating electricity in space is far more demanding than on Earth. Solar cells must operate in vacuum, withstand energetic radiation, tolerate extreme temperature variations and continue producing useful power throughout a mission, all while adding as little mass as possibl...

Imagine you are travelling somewhere for a few months. You pack enough water for the journey, but eventually, you’ll run out. You would have to find a way to collect or produce more water along the way. Satellites face a similar problem, except what they need is energy. Luckily, they have a practically endless source right outside their windows: the Sun. Solar panels convert sunlight into electricity, powering everything from communication systems to scientific instruments. This is how many satellites keep themselves running for years. Indian satellites such as IRNSS-1F and GSAT-9 use multiple-junction solar cells and deployable solar arrays to generate hundreds or thousands of watts of power. NASA spacecraft and missions use similar solar technologies, from large deployable arrays to advanced multi-junction cells. But now, imagine taking this one step further. What if a satellite didn’t just use solar energy for itself, but supplied that energy to Earth? This is the idea behind Space-...