Happy (belated) Fourth of July! While everyone was out barbecuing and amusing themselves with colorful novelty explosions, there was big news in space exploration: NASA’s Juno probe, which launched from Earth five years ago, has finally reached the gas giant planet and entered orbit. The robot spacecraft, which is about the size of a basketball court, is now dancing nimbly amongst the system of moons and rings and radiation belts around the giant world.
The probe is a remarkable spacecraft. It traveled 2.7 billion kilometers (1.7 billion miles) to reach the exact orbit which NASA planned for it. The secret behind its astonishing precision (even when traveling at 165,000 mph) is the autonomy of its sophisticated navigational computer. Mission controllers do not have to radio the probe from half-way across the solar system (which would take minutes—or longer. Instead the probe navigates itself. The ship computer is shielded beneath a titanium vault to keep radiation from frying its clever electronic brain.
Among the planets, Jupiter is a sort of greedy eldest child. Scientists who study planetary formation believe that the gas giant formed first of all the planets and it took the lion’s share of available matter left over from the formation of the sun. Jupiter is more than twice as massive as all the other planets in our solar system put together: indeed, it is three hundred and eighteen times more massive than Earth. Yet we know shockingly little about this bruiser. Very basic questions about Jupiter remain unanswered. For example we still do not know whether the planet has a rocky core beneath its vast colorful atmosphere.
As we learn more about exoplanets which orbit other stars, questions about the formation of solar systems have become more numerous. Astronomers have been particularly perplexed by the number of “hot Jupiters,” giant gas planets which are extremely close to their stars. Was Jupiter such a world at some point before moving to its current location, or is it a huge freak? We simply do not know. Scientists would also like to know more about the unimaginably vast cloudscapes of Jupiter. What dynamics move these huge bands of pressurized gas?
As Jupiter formed, it was bombarded by strange radiation. The depths of Jupiter’s storms must still feature giant lightning strikes. This sort of treatment can cause hydrocarbons and ammonia to form amino acids. Maybe life has a Jovian origin. Maybe Jupiter still has life floating around like aerial zooplankton. Again, we just don’t know much about the giant world…
However, now that Juno has arrived we can start to answer some of these questions. The probe will go through various start-up and test sequences until Oct. 19 when it moves to a 14-day orbit of the planet and really starts scrutinizing our giant neighbor.
Oh, one more thing—NASA has been getting better at PR to make space more accessible and “fun” for us laypeople following at home (as witnessed by the July 4th arrival). Juno also has a crew of three Lego astronauts: Galileo, Jupiter, and Juno herself. This leads me to write about Juno herself, for she is a terrifying figure among the gods. More about her tomorrow!