Cassini’s Grand Finale

On September 15, one of the most fruitful space missions ever imagined will come to an end. After two decades in space, Cassini’s fuel supplies are close to being depleted. To avoid contaminating one of Saturn’s moons, including a pair that could harbor life–Enceladus and Titan–the decision was made to retire Cassini into Saturn’s atmosphere. Up until contact between the orbiter and Earth is lost, Cassini will continue to study our beloved ringed planet. New insight will be gleaned from this mission that’s only made possible by Cassini’s fatal approach to the gas giant. Among the data to be collected:

  • The spacecraft will make detailed maps of Saturn’s gravity and magnetic fields, revealing how the planet is arranged internally, and possibly helping to solve the irksome mystery of just how fast Saturn is rotating.
  • The final dives will vastly improve our knowledge of how much material is in the rings, bringing us closer to understanding their origins.
  • Cassini’s particle detectors will sample icy ring particles being funneled into the atmosphere by Saturn’s magnetic field.
  • Its cameras will take amazing, ultra-close images of Saturn’s rings and clouds.

Cassini launched on Oct. 15, 1997. After a seven-year journey the orbiter arrived at Saturn, carrying the European Space Agency’s Huygens probe. In 2005, the probe successfully landed on Saturn’s largest moon, Titan.


Quick facts about Titan:

  • Titan is the solar system’s second largest moon.
  • It’s the only moon in our solar system that has cloud systems and a dense, planet-like atmosphere.
  • Titan has liquid hydrocarbon lakes, mountains, and seasonal weather patterns.

For 13 years, Cassini has orbited Saturn and provided us with fascinating information about, not just the planet, but its intricate ring system and many moons.

Cassini mission overview infographic

Cassini mission overview infographic – Click for larger version – Source: NASA/JPL

In addition to the important scientific data that was collected by Cassini, are the breathtaking images that have been collected: storms and aurorae on Saturn, detailed views of the worlds that are Saturn moons, and remarkable visions of Saturn’s sensational rings.

For the next week, we celebrate Cassini’s achievements.

Still from the short film Cassini's Grand Finale, the spacecraft is shown diving between Saturn and the planet's innermost ring.

Still from the short film Cassini’s Grand Finale, the spacecraft is shown diving between Saturn and the planet’s innermost ring. – Credit: NASA/JPL-Caltech

What’s Up: September 2017

It’s September and a wonderful time to enjoy the night sky. In northern latitudes, the length of night is generally outpacing the upcoming winter chill. Spring and Fall are great times to become reacquainted with the cosmos.

Here’s a brief run-down of what to expect in the September skies (note: this information is tailored to those of us in the Northern Hemisphere).

What’s that planet?:
If it’s in the evening, it’s most likely Jupiter. If it’s in the morning, you might be seeing Venus, Mercury or Mars.

This month, Jupiter is its bold, bright self, but it’s tracking fairly close to the Sun and setting in the southwest. You’ll see it shortly after sundown, earlier and earlier the further north you are. In October, Jupiter will be outside of our view until its return in November. On September 21 and 22, Jupiter will appear very near to a thin crescent Moon. Saturn is also up during September nights, though you’ll want to consult a star chart or skymap app to find it due to it being hard to distinguish from stars. Speaking of Saturn, September 15 marks the grand finale of the Cassini spacecraft. After 20 years of astonishing service, Cassini will plunge into Saturn’s atmosphere and end one of the most successful space missions imagined.

On September mornings, keep an eye out for Venus, Mars, and Mercury. Venus is hard to miss, it’s the brightest object in the sky following the Sun and Moon. Keep an eye to the east about two hours before sunrise (closer to sunrise the later we get into the month) for our bright sister planet.

If you’re fortunate enough to live on the mid-northern latitudes, you might get to witness a fantastic conjunction of Mercury and Mars. (If you’re as far north as Alaska, you’ll need a clear view of the horizon.) On September 16, Mercury and Mars appearing extremely close to each other in the morning sky. Use this website to get a custom report for your viewing location.

If you need help finding out when a planet rises and sets for your location, this website is fairly indispensable.

Happy viewing!

First Star of the Season

I live in Alaska. When you’re this far north, summer daylight is never-ending. We go months without seeing a star other than our sun. It’s no coincidence that this blog essentially goes into hiatus during the summer months. After a very long and dark winter, my interests naturally shift back to things on the Earth, rather than above it.

With autumn comes darkness, bringing the added benefit of it still being warm enough to spend plenty of time comfortably observing the night sky. Last weekend, I watched the first stars wink on since Spring. The first star of my stargazing season was the brilliant cornerstone of the constellation Aquila (the Eagle), Altair.

Aquila

Image Credit: Till Credner, AlltheSky.com

Altair is our relative neighbor, at only 16.8 light years from our solar system. Its proximity, size (1.8 times the mass of the Sun) and luminosity (11 times that of our host star) make it one of the brightest stars in the night sky.

Altair is rapidly-rotating, completing a revolution around every 9 hours. For contrast, our sun completes a revolution about once every 30 days. This rapid spinning actually influences the star’s shape, flattening it out slightly and giving it a more oval shape–think about how pizza dough flattens out when a pizza chef spins it overhead.



For me, Altair marks only the beginning of a long winter of dark skies. I’m looking forward to it.

STS-1 Columbia – The Shuttle Program’s First Flight

It happened exactly 20 years after cosmonaut Yuri Gagarin became the first human in space. It was the first American manned spaceflight in six years, following the 1975 Apollo-Soyuz Test Project. It was the beginning of an era that ushered in a new generation of spaceflight technology.

STS-1 Mission Patch

STS-1 Mission Patch – Credit: NASA

It was STS-1, the first of more than 130 flights of the Space Shuttle program.

Shuttle Columbia was selected for the maiden voyage of the program. Not only was this the first crewed flight for the shuttle, it was the first flight period. Shuttle Enterprise had been utilized for flight (and landing) tests within the atmosphere, but wasn’t designed to be space-ready (including not having a heat shield for re-entry).

So Columbia was not only a mission, but a flight test in its own right. Her crew consisted of Commander John W. Young and pilot Robert L. Crippen. Young was already a veteran of the space program, having flown as pilot of the Gemini Program’s first manned flight (Gemini 3 – known around these parts as that time John Young smuggled a corned beef sandwich into space), served as commander of Gemini 10, was the command module pilot of Apollo 10 (the “dress rehearsal” for Apollo 11), and also walked on the Moon as commander of Apollo 16. This, however, would be Crippen’s first spaceflight. Both of these men were qualified test pilots, and STS-1 was one heck of a test flight.

At 7:00am on April 12, 1981, after a two-day delay, STS-1 lifted off from Launch Pad 39A at Kennedy Space Center–the same launch pad that took Neil Armstrong, Buzz Aldrin, and Michael Collins to the Moon, and is currently leased to SpaceX where it will serve to create a new type of spaceflight history. The launch was just as flawless as Launch Controller Chuck Hannon wished, when one minute and forty-five seconds prior to lift-off, he told the crew: “Smooth sailing, baby.”

STS-1 Columbia at launch on April 12, 1981

STS-1 Columbia at launch on April 12, 1981 – Credit: NASA

SHUTTLE LAUNCH CONTROL: T minus ten, nine, eight, seven, six, five, four, we’ve gone for main engine start, we have main engine start. And we have lift off of America’s first space shuttle, and the shuttle has cleared the tower.

Minutes later, Columbia and her crew were beginning the first of 37 total orbits to take place over the course of just more than two days. A new era was born, as we became a world with reusable space planes.




The primary mission of STS-1 was to conduct a general check-out of the Space Shuttle system, reach orbit successfully, and land safely back on Earth. Despite a few anomalies, which were recorded and solved for future flights, STS-1 was a smashing success. Orbiter Columbia performed amazingly and would be used for the next four shuttle missions until STS-6, when Challenger became the second orbiter in the fleet.

STS-1 was the solid first step in the three decades-long adventure that was the Space Shuttle program.

A Fictive Flight Above Real Mars

You deserve a break. I recommend you take a few minutes to watch this jaw-dropping creation by Jan Fröjdman. Fröjdman retrieved thousands of stereoscopic images from the HiRISE camera onboard the Mars Reconnaissance Orbiter. He assembled them into a video, and post-processed it into the masterpiece below. Enjoy.

(Make Full-Screen and HD for the most amazing results.)

MISSE: Testing Materials In Space

If you had a really, really, really good telescope and took a peep at the International Space Station (which would be quite a feat for as quickly as it moves across the sky), you might notice what looks like a make-up kit or a watercolor palette dangling from the side of the station.

MISSE-3 just prior to retrieval during an STS-118 spacewalk.

MISSE-3 just prior to retrieval during an STS-118 spacewalk. – Credit: NASA

While some astronauts have taken their makeup into space, and some have found time to create art in orbit, they don’t tend to leave their supplies attached to the outside of the ISS. Ruling those out, instead what you’d probably be looking at is a Materials International Space Station Experiment (MISSE).

MISSE project specimens are placed onto trays and inserted into Passive Experiment Containers (PECs).

MISSE project specimens are placed onto trays and inserted into Passive Experiment Containers (PECs). – Credit: NASA

MISSE projects serve as a laboratory to test and study various material samples as they’re exposed to a space environment. Attached on the outside of the ISS, the specimens are simultaneously exposed to a variety of conditions that would be very difficult, if even possible, to mimic on Earth, including exposure to: atomic oxygen, various levels of radiation, vacuum, extreme temperatures, and zero gravity. While MISSE wasn’t the first project of this type–similar experiments had been carried out on Skylab, Mir, and NASA’s Long Duration Exposure Facility (LDEF)–it was the most formal and programmatic.

The first two MISSE projects were deployed in 2001, carried to the ISS via the Discovery crew of STS-105. They were originally planned to only be deployed for one year, but as a result of the grounding of the Shuttle program following the STS-107 Columbia disaster, they ended up staying in orbit for 3 years. There were a total of 8 MISSE experiments conducted by NASA, sometimes deployed in multiples and sometimes singly.

NASA astronaut Andrew Feustel swaps the MISSE PEC7A & 7B with PEC8

NASA astronaut Andrew Feustel swaps the MISSE PEC7A & 7B with PEC8 – Credit: NASA

The samples are loaded into trays and installed inside suitcase-like Passive Experiment Containers (PECs). When ready to be deployed, the PECs are carried outside the station during an EVA (extra vehicular activity), and fastened to the station’s exterior. The mounting location has changed throughout the program’s history.

Samples from MISSE 3 and 4 carried 8 million basil seeds that were then provided “to children for science experiments to stimulate interest in space science”. Other samples included paints, lubricants, fabrics, and solar cell technologies. In total, more than 4,000 samples have been tested through MISSE.

As part of NASA’s efforts to privatize routine space projects, MISSE was recently transferred to the private corporation Alpha Space:

MISSE is now a privatized, commercial facility owned and operated by Alpha Space with a permanent placement on the ISS. The facility and its first set of experiments have been manifested to fly to the International Space Station in September of 2017 on the SpaceX Dragon resupply vehicle’s flight SpaceX-13.





Now dubbed MISSE-FF (Material International Space Station Experiment Flight Facility), Alpha Space’s contract is good through at least June 30, 2024 (currently the authorized remaining lifetime of the station). Alpha Space’s plans call for a permanently-mounted tower that will hold multiple PECs at once. If the customers are there (some have already signed contracts), Alpha Space is ready to provide routine testing in the unparalleled environment of space. They expect to begin operations this year (2017).

Animation of Alpha Space's PEC deployment

Animation of Alpha Space’s PEC deployment – Source: Alpha Space

Cosmic Paparazzi: The Twin Jet Nebula

The Twin Jet Nebula, or PN M2-9

The Twin Jet Nebula, or PN M2-9 – Image credit: ESA/Hubble & NASA

SpaceTelescope.org: The Twin Jet Nebula, or PN M2-9, is a striking example of a bipolar planetary nebula. Bipolar planetary nebulae are formed when the central object is not a single star, but a binary system, Studies have shown that the nebula’s size increases with time, and measurements of this rate of increase suggest that the stellar outburst that formed the lobes occurred just 1200 years ago.

Cygnus Loop and the Veil Nebula

Between 5,000 and 8,000 years ago, a star many times more massive than our Sun met its end in a fantastic supernova explosion. The supernova remnant–the observable aftermath of that ancient star’s spectacular demise–is known as the Cygnus Loop. Not all of the radiation from the remnant is in the visual spectrum however–meaning our eyes can’t see the entire structure–but the portion that does fall within the visible spectrum is a popular target for professional and amateur astronomers and is commonly referred to as the Veil Nebula.

[Left] – This is a sky survey image of the Veil Nebula, a 110-light-year-wide expanding remnant of a star that exploded about 8,000 years ago in the constellation Cygnus.

[Center] – This is a ground-based telescope image of a 15-light-year-long stretch of the eastern portion of the nebula.

[Right] – This image shows a two-light-year-wide segment of the remnant as photographed by NASA’s Hubble Space Telescope. Hubble resolves tangled rope-like filaments of glowing gases.

What I love about the Cygnus Loop, and most other features of the night sky, is how we can discover more than what just our eyes can see. We often forget, or maybe don’t even realize, that our eyes are only sensitive enough to see a small portion of the entire electromagnetic spectrum. We refer to this narrow band of electromagnetic radiation as visible light.

Comparison of wavelength, frequency and energy for the electromagnetic spectrum.

Comparison of wavelength, frequency and energy for the electromagnetic spectrum. (Credit: NASA’s Imagine the Universe)

The part of the Cygnus Loop that’s observable in visible light, which is referred to as the Veil Nebula, looks like this:

Now, if the range of electromagnetic radiation our eyes can sense were expanded just a bit into the ultraviolet part of the spectrum, we’d see the Cygnus Loop like this:

Cygnus Loop in ultraviolet

Cygnus Loop in ultraviolet – Credit: NASA/JPL-Caltech

In ultraviolet, otherwise invisible or very faint wisps of gas are much more pronounced and show that there’s much more to this stellar spectacle than meets the eye.

 

SpaceX Continues To Make History

SpaceX is no stranger to making commercial spaceflight history. They were the first private corporation to launch a liquid-fueled rocket into orbit, send a re-supply spacecraft to the International Space Station, and to land their first-stage rockets back on Earth (for potential re-use), among other milestones. They’re also on the cusp of providing transportation services for International Space Station crew members.

SpaceX Falcon 9 moments before landing on February 19, 2017

SpaceX Falcon 9 moments before landing on February 19, 2017 – Source: SpaceX

On February 19, 2017, SpaceX accomplished another major feat: They became the first private company to launch from the historic Launch Pad 39A at Kennedy Space Center.

Launch Pad 39A

SpaceX became the first commercial corporation to lease space and operate out of Kennedy Space Center when, in 2014, they signed a 20-year lease for the historic Launch Pad 39A. It was from this launch pad that Apollo 11 blasted off for the Moon, when Neil Armstrong and Buzz Aldrin became the first humans to step foot on our lunar neighbor. It also hosted the first Space Shuttle mission, as well as some 90 others. Now, and for at least the next two decades, it’s in the hands of SpaceX, further cementing the foothold that the private sector has made in the space program.

SpaceX and NASA CRS-10 mission patches

SpaceX and NASA CRS-10 mission patches – Source: Public Domain and SpaceX

Launch and Landing

At 9:39am EST, on February 19, SpaceX’s Falcon 9 rocket ignited and thundered into the clouds. The rocket was topped with the Dragon capsule, carrying more than 5,000 pounds (2,267 kg) worth of cargo destined for the International Space Station. Dragon arrived and successfully docked with the ISS a couple of days following launch.

Dr. Michelle Thaller, NASA astrophysicist and contributor to myriad space documentary programs, was at Sunday’s launch and graciously shared her experience with me. “Launches are always wonderfully, viscerally exciting,” she said. “The Falcon 9 has a wonderful, big, booming sound, similar to an Atlas, and it puts on a great fireworks show.”

But that wasn’t the only show in store for the lucky spectators in Florida that day. After shoving Dragon into orbit, the Falcon first stage began its 100-kilometer return trip back to Earth. In fewer than 10 minutes following lift-off, the first stage rocket re-emerged through the clouds and landed at Landing Zone 1, just a few miles away from the launch pad. Thaller described the period of suspense in between the launch and the Falcon landing, and said that in some ways there was more anticipation for the landing than there was for the launch.

[N]othing quite prepares you for what happens 7 minutes later, just as the adrenaline is wearing off. Silently, at first, this 230-foot first stage turns around and comes down out of the sky. Smoothly, surreally, a tower the size of a 15 story building just comes and sets itself down. Only once it’s down do you hear the double pop of a sonic boom. It sort of turns your stomach. Things that big are not supposed to just come out of the sky and land. It’s awesome.

Awesome, indeed. See for yourself:

As a kid, I remember watching cartoons that showed rockets landing on various planets. The rockets would turn themselves around and gently land engine-side down. I would always exclaim, “That’s not how rockets work! They burn up, or have parachutes attached and they land in the ocean! How silly.”

Yet, here we are.

I’ve often been jealous about being born too late to experience the race to the Moon. I’ve been somewhat depressed since watching the last Shuttle mission touch down in 2011. But when I take a step back and look at what is occurring today and what we have to look forward to, I can’t help but recognize what a wonderful time it is to be alive.

You can watch the full webcast of the launch on SpaceX’s YouTube channel.

7 Earth-Sized Worlds Discovered Orbiting Nearby Star

Artist's concept of the surface of TRAPPIST1-f.

Artist’s concept of the surface of TRAPPIST1-f. – Credit: NASA/JPL-Caltech

NASA held a press conference today, announcing an exciting new discovery: A record-breaking seven Earth-sized planets have been discovered orbiting a star located about 40 light years from Earth. Three of these planets are firmly located within what’s called the habitable zone–the area around a star that is likely to have rocky planets with liquid water.

The star is named TRAPPIST-1 (also known as 2MASS J23062928-0502285). It’s an ‘ultra-cool dwarf’ star, with approximately 8% of the mass and 11% of the radius of our Sun. Size-wise, this is approximately the difference between a basketball and a golfball.

The seven plants surrounding TRAPPIST-1 orbit much closer to their star than Earth does to the Sun. As well, these exoplanets are much closer to each other than the planets in our own system. You could stand on one of these planets and see the next closest one with a similar type of view that we have with the Moon here on Earth, and you could clearly make out the disc-shape of many of the other planets rather than mere points of light.

The discoveries were made using data from the Spitzer Space Telescope, which was launched in 2003. Although Spitzer wasn’t specifically designed to observe exoplanets, the suite of instruments it carries allows it to discover exoplanets in the same manner that the Kepler spacecraft uses. These observatories can discover exoplanets by precisely measuring dips in the light emitted from a star that coincides with a planet orbiting in-between that star and our vantage point and blocking a portion of the light that we can measure. Continued observations can determine orbital periods, distance from the star, and the number of exoplanets in a system. This data can be used to plot habitable zones.

During the press conference, the team stated that they had preliminary mass measurements for six of the planets, and they believe that one is likely to have a water-rich composition.

Artist's concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances.

Artist’s concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances. – Credit: NASA/JPL-Caltech

There currently isn’t a system for naming exoplanets in the way that bodies like asteroids are named, so they’re simply provided with alphabetic designations appended to their host stars’ name, with the designation ‘b’ being the closest to the star.

These planets orbit so close to their star that they’re likely tidally-locked in the same manner that the Moon is to the Earth. These planets would have permanent day and night sides.

One of the planets, Trappist-1c, is very similar in size to Earth and receives about the same amount of light as Earth receives from the Sun. It could very well have temperatures similar to those we have on Earth. Trappist-1f has a 9-day orbit and receives about as much light as Mars does. Trappist-1g is the largest planet in the system with an estimated radius 13% larger than Earth.

All of the planets are within a few times the distance between the Earth and the Moon of each other, and being so close to their star their orbits (their years) are about 1.5 Earth days for the closest planet and 20 days for the furthest.

Concept art for TRAPPIST-1 and its seven Earth-sized exoplanets.

Concept art for TRAPPIST-1 and its seven Earth-sized exoplanets. – Credit: NASA/JPL-Caltech

The next step, which is already ongoing, is to study their atmospheres and to look for water. This can be accomplished using a technique called transmission spectroscopy. We have observatories that can do this now, such as the Hubble Space Telescope, and the future James Webb Space Telescope (JWST) will be able to push these capabilities even further. JWST will be able to look for greenhouse gas content and determine the surface temperatures of these planets, as well as detect gases that are produced by life. It’s expected that the first cycle of observations of the JWST will include the TRAPPIST-1 system.

Thomas Zurbuchen, associate administrator of the agency’s Science Mission Directorate in Washington, referred to our moment in time as “the gold rush phase of exoplanet discovery.”  It was just in 1995 that the first exoplanet was discovered, he explained, and that thousands have been discovered since.

Following the announcement, the panel held a Q&A session. During the course of their answers, they explained that there was no indication of these planets having moons, but that if water was present there would be tidal activity resulting from the other planets. They said they expect substantial progress in determining the atmospheric composition of these exoplanets within the next 5 years, utilizing the Hubble Space Telescope and the James Webb Space Telescope after it begins operations in 2018. JWST’s transmission spectroscopy will cover the range needed to determine the potential for life.

One member asked if any attempts have been made to listen to the system with SETI-style instruments, to which there was a reply that SETI itself had listened to the system but hadn’t picked-up any signals.

One of the most interesting answers came from Zurbuchen, when he was asked when we could expect to construct a craft that could journey to this system. Rather than give an estimate in the number of years in the future we could expect such capabilities, he answered with the estimated “number of miracles” that are required before we get there. He explained that the JWST required 10 miracles to become possible. He likened the construction of a craft that could explore TRAPPIST-1 as requiring “100 miracles”, but that we shouldn’t be dissuaded, that to get there you have to “start inventing your way forward.” Some of the “miracles” require advancements in propulsion systems and radiation-protection, and that the good news was that substantial work is already being accomplished towards about 5-10 of these miracles. He said it’s about “leaning forward” and “not backing up”.

Discoveries like these are constant reminders of just how big and amazing our Universe is. We’re reminded that the night sky isn’t just full of points of light, but worlds, perhaps some of which might be very similar to our own.

A poster advertising a hypothetical planet-hopping trip in the Trappist-1 system

A poster advertising a hypothetical planet-hopping trip in the Trappist-1 system – Credit: NASA-JPL/Caltech