Cassini Spacecraft: Top Discoveries

Landing Day for InSight by NASA’s Marshall Space Flight Center

September 15

This one is technically not yet history, because at the time of posting, the little craft has about half an hour left to go.  That said, let’s proceed.

In 2017, NASA’s Cassini space probe ended its twenty-year mission at Saturn.  After a nearly-seven-year-long journey there, it orbited the ringed planet for 13 years and just over two months, gathering copious amounts of information about the planet, said rings, and many of its moons.  It landed an ESA probe called Huygens on Titan, the first-ever soft landing in the outer Solar System.  It discovered lakes, seas, and rivers of methane on Titan, geysers of water erupting from Enceladus (and passed within 50 miles of that moon’s surface), and found gigantic, raging hurricanes at both of Saturn’s poles.  

And the images it returned are beautiful enough to make you weep.

On this day in 2017, with the fuel for Cassini’s directional thrusters running low, the probe was de-orbited into the Saturnian atmosphere to prevent any possibility of any contamination of possible biotic environments on Titan or Enceladus.  The remaining thruster fuel was used to keep the radio dish pointed towards Earth so the probe could transmit information about the upper atmosphere of Saturn while it was burning up due to atmospheric friction.

This is us at our best.  We spent no small amount of money on a nuclear-powered robot, launched it into space, sent it a billion miles away, and worked with it for two decades just to learn about another planet.  And when the repeatedly-extended missions were through, we made the little craft sacrifice itself like a samurai, performing its duty as long as it could while it became a shooting star in the Saturnian sky.

Rhea occulting Saturn

Water geysers on Enceladus

Strange Iapetus

Look at this gorgeousness

A gigantic motherfucking storm in Saturn’s northern hemisphere

Tethys

This image is from the surface of a moon of a planet at least 746 million miles away.  Sweet lord

Mimas

Vertical structures in the rings.  Holy shit

Titan and Dione occulting Saturn, rings visible

Little Daphnis making gravitational ripples in the rings

That’s here.  That’s home.  That’s all of us that ever lived.

Saturn, backlit

A polar vortex on the gas giant

Icy Enceladus

(All images from NASA/JPL)

Saturn With Quadruple Moon Presence – Hubble Telescope

Pluto’s Surface Changes Faster Than Earth’s, And A Subsurface Ocean Is Driving It

“These mountains aren’t static and stable, but rather are temporary water-ice mountains atop a volatile, nitrogen sea. The evidence for this comes from multiple independent observations. The mountains only appear between the hilly highlands, after the edge of a basin rim, and young plains with flowing canals. These young plains occur in Pluto’s heart-shaped lobe, which itself was caused by an enormous impact crater. Only a subsurface, liquid water ocean beneath the crust could cause the uplift we then see, leaving the nitrogen to fill it in.”

In July of 2015, NASA’s New Horizons Mission arrived at Pluto, photographing the world at the highest resolution ever, with some places getting as up-close as just 80 meters (260 feet) per pixel. Not bad for a world more than 3 billion miles (5 billion kilometers) from home! What we’ve learned is breathtaking. Rather than a static, frozen world, we found one with tons of evidence for active, interior geology, as well as with a changing surface that renews itself and undergoes cycles, quite unexpectedly to many. There’s also not an enormous heart, but rather a massive, volatile-filled crater that caused Pluto to tip over at least once in its past, and may yet cause it to tip over again in the near future.

If you ever wanted to know how these distant, icy worlds come alive, there’s never been a better way to find out than in the aftermath of what New Horizons taught us!

One Step Closer to the Moon with the Artemis Program! 🌙

The past couple of weeks have been packed with milestones for our Artemis program — the program that will land the first woman and the next man on the Moon!

Artemis I will be an integrated, uncrewed test of the Orion spacecraft and Space Launch System (SLS) rocket before we send crewed flights to the Moon.

On March 2, 2021, we completed stacking the twin SLS solid rocket boosters for the Artemis I mission. Over several weeks, workers with NASA's Exploration Ground Systems used one of five massive cranes to place 10 booster segments and nose assemblies on the mobile launcher inside the Vehicle Assembly Building at the Kennedy Space Center (KSC) in Florida.

On March 18, 2021, we completed our Green Run hot fire test for the SLS core stage at Stennis Space Center in Mississippi. The core stage includes the flight computers, four RS-25 engines, and enormous propellant tanks that hold more than 700,000 gallons of super cold propellant. The test successfully ignited the core stage and produced 1.6 million pounds of thrust. The next time the core stage lights up will be when Artemis I launches on its mission to the Moon!

In coming days, engineers will examine the data and determine if the stage is ready to be refurbished, prepared for shipment, and delivered to KSC where it will be integrated with the twin solid rocket boosters and the other rocket elements.

We are a couple steps closer to landing boots on the Moon!

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Blue Marble, Eastern Hemisphere March 2014 by NASA Goddard Photo and Video

July 20, 1969

Project Apollo on Flickr

Perseverance: Amazing descent & landing video taken by the rover’s EDL cameras.

Ocean on the moon Europa

Scientists' consensus is that a layer of liquid water exists beneath Europa's surface, and that heat from tidal flexing allows the subsurface ocean to remain liquid.

Europa's surface temperature averages about 110 K (−160 °C; −260 °F) at the equator and only 50 K (−220 °C; −370 °F) at the poles, keeping Europa's icy crust as hard as granite. The first hints of a subsurface ocean came from theoretical considerations of tidal heating (a consequence of Europa's slightly eccentric orbit and orbital resonance with the other Galilean moons). Galileo imaging team members argue for the existence of a subsurface ocean from analysis of Voyager and Galileo images.

The most dramatic example is "chaos terrain", a common feature on Europa's surface that some interpret as a region where the subsurface ocean has melted through the icy crust.

The thin-ice model suggests that Europa's ice shell may be only a few kilometers thick. However, most planetary scientists conclude that this model considers only those topmost layers of Europa's crust that behave elastically when affected by Jupiter's tides.

The Hubble Space Telescope acquired an image of Europa in 2012 that was interpreted to be a plume of water vapour erupting from near its south pole The image suggests the plume may be 200 km (120 mi) high, or more than 20 times the height of Mt. Everest.

Life?

So far, there is no evidence that life exists on Europa, but Europa has emerged as one of the most likely locations in the Solar System for potential habitability. Life could exist in its under-ice ocean, perhaps in an environment similar to Earth's deep-ocean hydrothermal vents. Even if Europa lacks volcanic hydrothermal activity, a 2016 NASA study found that Earth-like levels of hydrogen and oxygen could be produced through processes related to serpentinization and ice-derived oxidants, which do not directly involve volcanism.

In 2015, scientists announced that salt from a subsurface ocean may likely be coating some geological features on Europa, suggesting that the ocean is interacting with the seafloor. This may be important in determining if Europa could be habitable. The likely presence of liquid water in contact with Europa's rocky mantle has spurred calls to send a probe there.

Missions

Europa Clipper is an interplanetary mission in development by NASA comprising an orbiter. Set for a launch in October 2024, the spacecraft is being developed to study the Galilean moon Europa through a series of flybys while in orbit around Jupiter.

The Europa Lander is a proposed astrobiology mission concept by NASA to Europa, an icy moon of Jupiter. If funded and developed as a large strategic science mission, it would be launched in 2027 to complement the studies by the Europa Clipper orbiter mission and perform analyses on site. NASA's budget for fiscal year 2021 neither mandates nor allocates any funds to the mission leaving its future uncertain.

The objectives of the mission are to search for biosignatures at the subsurface ≈10 cm, to characterize the composition of non-ice near-subsurface material, and determine the proximity of liquid water and recently erupted material near the lander's location.

source