Farewell, InSight Lander!

On Saturday, May 5, NASA is launching its newest Mars lander. The Mars InSight lander is set to arrive at Mars in November. This spacecraft is a first of its kind because it will be launched from the West Coast unlike other launches to Mars. More importantly, however, this lander is unique because it will attempt to peer beneath the surface of Mars; past rovers have only been able to explore their surroundings and at most collect samples and drill into the topsoil. Unlike the past rovers, the InSight lander will stay still, rather than moving around Mars’s surface, so that it can measure the internal properties of Mars. One thing the Insight lander is set to look for is marsquakes, or seismic activity on Mars. Earthquakes on Earth are caused by plate tectonics, whereas marsquakes are caused by volcanism. When a marsquake occurs, the InSight will be able to take a picture of Mars’s interior for astronomers on Earth to see. The goal is that greater study of Mars’s interior will be able to give us more insight into how Mars was formed. We have a general idea about how rocky terrestrial planets like Mars were formed, but we would like to learn more about how Mars came to be the cold, geologically dead world it is today.


Illustration of InSight from NASA

Some of the information to be gathered includes the thickness of Mars’s crust and the composition of its mantle and core. In particular, three main experiments will be conducted by InSight. The Seismic Experiment for Interior Structure will track marsquakes and internal activity. This will tell us more about Mars’s history and structure. The Heat Flow and Physical Properties Package will measure the movement of heat under Mars’s surface. This will tell us more about how Mars’s interior has evolved over time. The Rotation and Interior Structure Experiment will use radio signals to detect rotational wobbles. This will tell us more about the properties of the core and the interaction between the core and the mantle. It is the hope of scientists that with the results from this mission, we will be able to better understand how and why Mars formed the way it did and what it would take for worlds similar to Mars to form, whether they be terrestrial worlds in our own solar system or even exoplanets in other star systems. Fascinatingly enough, these studies of Mars’s interior will help the scientific community learn about planetary formation and evolution that extends beyond our own solar neighborhood!

Putting the speed of light into perspective

The theory of special relativity tells us that there is an absolute speed limit in the universe, that being the speed of light. At a speed of about 300,000 km/s, light takes only one second to travel to the Moon from Earth and eight minutes to travel to the Sun from Earth. This speed is extremely fast for human standards. For instance, in 2016, NASA’s Juno spacecraft arrived at Jupiter, accelerating to a speed of about 265,000 km/h. This made it the fastest human-made object in history. Still, this speed of 265,000 km/h is nowhere close to light’s speed of 300,000 km/s.

However, not even light seems fast in the context of just how massive our universe is. For example, it takes light four years to reach Earth from Alpha Centauri, the star system nearest to us besides the Sun. It takes light 6,000 years to reach us from the Crab Nebula, the remnant of a massive star in the direction of Taurus. It takes light 2 million years to reach us from the Andromeda Galaxy, the nearest galaxy to our own. It takes light 650 million years to reach us from the Hercules Cluster of galaxies. Keep in mind, the universe’s expansion started approximately 14 billion years ago, so there are even farther objects that light would take even longer to travel to Earth from!

Given these facts, convenient interstellar space travel seems like an impossible feat. The fastest object humankind has managed to create couldn’t even travel in an hour the distance that light travels in a second. And our spacecrafts that humans can actually travel on are even slower! So if we can’t travel faster than light, and light takes at least millions of years to reach nearby galaxies, then traveling through the universe like we’re in Star Trek seems hopeless!

Nevertheless, it is important to point out that special relativity involves local laws of physics. We may not be launching rockets faster than the speed of light, but general relativity tells us that these rules do not apply for galaxies at the far side of the universe. So does that mean a speed faster than the speed of light exists in the universe? In fact, the universe expands faster than the speed of light. The observable universe is only some fraction of the entire universe. Additionally, we know that the early universe underwent a phase of rapid, exponential expansion, and more distant objects move faster away from us than less distant objects.

Therefore, it makes sense that there would have been points during the entire universe’s expansion in which objects were moving away from other objects faster than the speed of light relative to each other or that the very distant objects at the outermost parts of the universe that are moving away faster and faster away from us will eventually exceed the speed of light if they have not already. As for the question of whether or not humans will find a way to exceed the speed of light, we may have to simply hope that we will someday find a way to use wormholes to transport to other worlds!


Universe Expansion (from Scienceline)