ESA Awakens Rosetta’s Comet Lander

Artist's impression (not to scale) of the Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko. Credit: ESA–C. Carreau/ATG medialab.

Little Philae is awake! ESA sent a wake-up call to the 100-kg (220-lb) lander riding aboard the Rosetta spacecraft this morning at 06:00 GMT, bringing it out of its nearly 33-month-long slumber and beginning its preparation for its upcoming (and historic) landing on the surface of a comet in November.

Unlike Rosetta, which awoke in January via a pre-programmed signal, Philae received a “personal wake-up call” from Earth, 655 million kilometers away.

Hello, world! ESA's Rosetta and Philae comet explorers are now both awake and well!
Hello, world! ESA’s Rosetta and Philae comet explorers are now both awake and well!

A confirmation signal from the lander was received by ESA five and a half hours later at 11:35 GMT.

After over a decade of traveling across the inner Solar System, Rosetta and Philae are now in the home stretch of their ultimate mission: to orbit and achieve a soft landing on the inbound comet 67/P Churyumov-Gerasimenko. It will be the first time either feat has ever been attempted — and hopefully achieved — by a spacecraft.

Read more: Rosetta Spacecraft Spies Its Comet As It Prepares For An August Encounter

After Rosetta maneuvers to meet up with the comet in May and actually enters orbit around it in August, it will search its surface for a good place for Philae to make its landing in November.

With a robotic investigator both on and around it, 67/P CG will reveal to us in intimate detail what a comet is made of and really happens to it as it makes its close approach to the Sun.

“Landing on the surface is the cherry on the icing on the cake for the Rosetta mission on top of all the great science that will be done by the orbiter in 2014 and 2015. A good chunk of this year will be spent identifying where we will land, but also taking vital measurements of the comet before it becomes highly active. No one has ever attempted this before and we are very excited about the challenge!”
– Matt Taylor, Rosetta project scientist

Meanwhile, today’s successful wake-up call let the Rosetta team know Philae is doing well. Further systems checks are planned for the lander throughout April.

Watch an animation of the deployment and landing of Philae on comet 67/P CG below:

Source: ESA’s Rosetta blog

Want to welcome Rosetta and Philae back on your computer? Download a series of ESA’s “Hello, World” desktop screens here.

Opportunity Rover Gets Power Boost from Wind Events on Mars

A nearly dust-free solar panel for the Opportunity rover following a dust cleaning wind event sometime during the last week of March 2014 (on Earth). Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State University.

The Opportunity rover on Mars has gotten a 70% boost in power over the past few weeks. A good portion of that comes from the fact that its springtime in Mars’ southern hemisphere where Oppy now sits along the western rim of Endeavour Crater and so the Sun is now shining longer and higher in the sky. But also, several recent gusts of wind – or perhaps small dust devils – have cleaned much of the dust off the rover’s solar panels.

The rover team reported that between Sols 3605 and 3606 (March 15 and March 16, 2014), there was a dust cleaning event that resulted in about a 10% improvement in power production to 574 watt-hours, and then another cleaning event this week has put the power output to 615 watt-hours.

See a self-portrait that Opportunity took of its solar panels back in January to compare with the image above of how much cleaner the solar panels are now.

To celebrate 10 years of the Opportunity rover on Mars, the rover team used the panoramic camera (Pancam) to take images of the rover itself during the interval Jan. 3, 2014, to Jan. 6, 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
To celebrate 10 years of the Opportunity rover on Mars, the rover team used the panoramic camera (Pancam) to take images of the rover itself during the interval Jan. 3, 2014, to Jan. 6, 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

Of course, this is not the first time a wind cleaning event has dusted off the solar panels — in fact it has happened several times (see here, here, and here) which is one of the reasons for the longevity of the solar-powered rovers.

I love these self-images the rovers can take, and below is a great recent image the rover took of its own shadow, in the late-afternoon Sun. The image was taken by the rover’s rear hazard avoidance camera.

Late afternoon lighting produced a dramatic shadow of NASA's Mars Exploration Rover Opportunity photographed by the rover's rear hazard-avoidance camera on March 20, 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
Late afternoon lighting produced a dramatic shadow of NASA’s Mars Exploration Rover Opportunity photographed by the rover’s rear hazard-avoidance camera on March 20, 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

The image was taken looking eastward shortly before sunset on Sol 3,609 (March 20, 2014). The rover’s shadow falls across a slope called the McClure-Beverlin Escarpment on the western rim of Endeavour Crater, where Opportunity is investigating rock layers for evidence about ancient environments. The scene includes a glimpse into the distance across the 14-mile-wide (22-kilometer-wide) crater.

Source: JPL

An Afternoon on Mars

A post-processed mosaic of MSL Mastcam images from Sol 582 (NASA/JPL-Caltech/MSSS. Edit by Jason Major)
Afternoon on Mars (MSL Mastcam mosaic)(NASA/JPL-Caltech/MSSS. Edit by Jason Major)

Here’s a pretty picture for your Friday: a mosaic of Mastcam images acquired by Curiosity on mission Sol 582, also known to us Earthlings as Thursday, March 27, 2014. Barsoom sure looks lovely this time of year!

The mosaic was assembled from five raw images downlinked to the MSL site earlier today. I pasted them together in Photoshop, aligning the edge of one to the next using landscape objects as visual markers, and then did a little bad pixel cleanup (Mastcam has a notorious black smudge a few pixels wide just off-center) and then cropped the result, with a bit of surface cloning at the lower right to fill in some missing Martian soil. The I hit it with an HDR filter, which I’m usually not a fan of but in in this instance it turned out pretty nice.

See s hi-resolution version of this on my Flickr album.

You can find all the raw images from Curiosity — including the ones I used to compose this image — here.

Image credit: NASA/JPL-Caltech/MSSS. Edit/composite by Jason Major.

Adventures in (Radio) Amateur Astronomy

 Is there truly anything new under the Sun? Well, when it comes to amateur astronomy, many observers are branching out beyond the optical. And while it’s true that you can’t carry out infrared or X-ray astronomy from your backyard — or at least, not until amateurs begin launching their own space telescopes — you can join in the exciting world of amateur radio astronomy.

We’ll admit right out the gate that we’re a relative neophyte when it comes to the realm of radio astronomy. We have done radio observations of meteor showers in tandem with optical observations, and have delved into the trove of information on constructing radio telescopes over the years. Consider this post a primer of sorts, an intro into the world of radio amateur astronomy. If there’s enough interest, we’ll follow up with a multi-part saga, constructing and utilizing our own ad-hoc “redneck array” in our very own backyard with which to alarm the neighbors and probe the radio cosmos.

Repurposing a TV Dish for amatuater astronomy. Credit: NSF/NRAO/Assoc. Universities, Inc.
The “Itty-Bitty Array”- Re-purposing a TV Dish for amateur astronomy. Credit: NSF/NRAO/Assoc. Universities, Inc.

…And much like our exploits in planetary webcam imaging, we’ve discovered that you may have gear kicking around in the form of an old TV dish – remember satellite TV? – in your very own backyard. A simple radio telescope setup need not consist of anything more sophisticated than a dish (receiver), a signal strength detector (often standard for pointing a dish at a satellite during traditional installation) and a recorder. As you get into radio astronomy, you’ll want to include such essentials as mixers, oscillators, and amplifiers to boost your signal.

Frequency is the name of the game in amateur radio astronomy, and most scopes are geared towards the 18 megahertz to 10,000 megahertz range. A program known as Radio-SkyPipe makes a good graphic interface to turn your laptop into a recorder.

Radio astronomy was born in 1931, when Karl Jansky began researching the source of a faint background radio hiss with his dipole array while working for Bell Telephone. Jansky noticed the signal strength corresponded to the passage of the sidereal day, and correctly deduced that it was coming from the core of our Milky Way Galaxy located in the constellation Sagittarius. Just over a decade later, Australian radio astronomer Ruby Payne-Scott pioneered solar radio astronomy at the end of World War II, making the first ever observations of Type I and III solar bursts as well as conducting the first radio interferometry observations.

A replica of Jansky's first steerable antanta at Green Bank, West Virginia.
A replica of Jansky’s first steerable antenna at Green Bank, West Virginia. (Public Domain image)

What possible targets exist for the radio amateur astronomer? Well, just like those astronomers of yore, you’ll be able to detect the Sun, the Milky Way Galaxy, Geostationary and geosynchronous communication satellites and more. The simple dish system described above can also detect temperature changes on the surface of the Moon as it passes through its phases. Jupiter is also a fairly bright radio target for amateurs as well.

Radio meteors are also within the reach of your FM dial. If you’ve ever had your car radio on during a thunderstorm, you’ve probably heard the crackle across the radio spectrum caused by a nearby stroke of lightning. A directional antenna is preferred, but even a decent portable FM radio will pick up meteors on vacant bands outdoors. These are often heard as ‘pings’ or temporary reflections of distant radio stations off of the trail of ionized gas left in the wake of a meteor.  Like with visual observing, radio meteors peak in activity towards local sunrise as the observer is being rotated forward into the Earth’s orbit.

Amateur SETI is also taking off, and no, we’re not talking about your crazy uncle who sits out at the end of runways watching for UFOs. BAMBI is a serious amateur-led project. Robert Gray chronicled his hunt for the elusive Wow! signal in his book by the same name, and continues an ad hoc SETI campaign. With increasingly more complex rigs and lots of time on their hands, it’s not out of the question that an amateur SETI detection could be achieved.

Another exciting possibility in radio astronomy is tracking satellites. HAM radio operators are able to listen in on the ISS on FM frequencies (click here for a list of uplink and downlink frequencies), and have even communicated with the ISS on occasion. AMSAT-UK maintains a great site that chronicles the world of amateur radio satellite tracking.

Amateur radio equipment that eventually made its way to to ISS aboard STS-106. (Credit: NASA).
Amateur radio equipment that eventually made its way to to ISS aboard STS-106. (Credit: NASA).

Old TV dishes are being procured for professional use as well. One team in South Africa did just that back in 2011, scouring the continent for old defunct telecommunications dished to turn them into a low cost but effective radio array.

Several student projects exist out there as well. One fine example is NASA’s Radio JOVE project, which seeks student amateur radio observations of Jupiter and the Sun. A complete Radio Jove Kit, to include receiver and Radio-SkyPipe and Radio-Jupiter Pro software can be had for just under 300$ USD. You’d have a tough time putting together a high quality radio telescope for less than that! And that’s just in time for prime Jupiter observing as the giant planet approaches quadrature on April 1st (no fooling, we swear) and is favorably placed for evening observing, both radio and optical.

Fearing what the local homeowner’s association will say when you deploy your very own version of Jodrell Bank in your backyard?  There are several online radio astronomy projects to engage in as well. SETI@Home is the original crowd sourced search for ET online. The Zooniverse now hosts Radio Galaxy Zoo, hunting for erupting black holes in data provided by the Karl Jansky Very Large Array and the Australia Telescope Compact Array. PULSE@Parkes is another exciting student opportunity that lets users control an actual professional telescope. Or you can just listen for meteor pings online via NASA’s forward scatter meteor radar based out of the Marshall Space Flight Center in Huntsville, Alabama. Adrian West also hosts live radio meteor tracking on his outstanding Meteorwatch website during times of peak activity.

Forward Scatter
A diagram of a basic forward scatter radar system for meteor observing. Credit: NASA

Interested? Other possibilities exist for the advanced user, including monitoring radio aurorae, interferometry, catching the hiss of the cosmic microwave background and even receiving signals from more distant spacecraft, such as China’s Yutu rover on the Moon.

Think of this post as a primer to the exciting world of amateur radio astronomy. If there’s enough interest, we’ll do a follow up “how-to” article as we assemble and operate a functional amateur radio telescope. Or perhaps you’re an accomplished amateur radio astronomer, with some tips and tricks to share. There’s more to the universe than meets the eye!

-Also be sure to check out SARA, the Society of Amateur Radio Astronomers.

Slip-Sliding Away: Solar Flare’s Magnetic Lines Go For A Loop In This Video

Our own Sun produces flares, but we are protected by our magnetosphere, and by the distance from the Sun to Earth. Credit: NASA/ Solar Dynamics Observatory,

When will the next big solar flare occur? How much damage could it cause to power lines and satellites? These are important questions for those looking to protect our infrastructure, but there’s still a lot we need to figure out concerning space weather.

The video above, however, shows magnetic lines weaving together from the surface of the Sun in 2012, eventually creating an eruption that was 35 times our planet’s size and sending out a surge of energy. It’s these energetic flares that can hit Earth’s atmosphere and cause auroras and power surges.

While models of this have been made before, this is the first time the phenomenon was caught in action. Scientists saw it using NASA’s Solar Dynamics Observatory.

Models of the flares show they typically occur amid distorted magnetic fields, the University of Cambridge noted, showing that the lines can “reconnect while slipping and flipping around each other.” Before the flare happens, the magnetic field lines line up in an arc across the sun’s surface (photosphere). That phenonemon is called field line footprints.

“In a smooth, non-entangled arc the magnetic energy levels are low, but entanglement will occur naturally as the footpoints move about each other,” the release added. “Their movement is caused as they are jostled from below by powerful convection currents rising and falling beneath the photosphere. As the movement continues, the entanglement of field lines causes magnetic energy to build up.”

When the energy gets to great, the lines let go of the energy, creating the solar flare and coronal mass ejection that can send material streaming away from the sun. A note, this observation was made of an X-class flare — the strongest kind of flare — and scientists say they are not sure if this phenomenon is true of all kinds of flares. That said, the phenomenon would be harder to spot in smaller flares.

You can read more about the research in the Astrophysical Journal or in preprint version on Arxiv. It was led by Jaroslav Dudik, a researcher at the University of Cambridge’s center for mathemetical sciences.

Source: University of Cambridge

1st Images from New NASA/JAXA GPM Rainfall Measuring Satellite Capture Tropical Cyclone in 3D

An extra-tropical cyclone seen off the coast of Japan, March 10, 2014, by the GPM Microwave Imager. The colors show the rain rate: red areas indicate heavy rainfall, while yellow and blue indicate less intense rainfall. The upper left blue areas indicate falling snow. Credit: NASA/JAXA

KENNEDY SPACE CENTER, FL – Weather researchers worldwide now have the ability to capture unprecedented three-dimensional images and detailed rainfall measurements of cyclones, hurricanes and other storms from space on a global basis thanks to the newest Earth observing weather satellite – jointly developed by the US and Japan.

NASA and the Japan Aerospace Exploration Agency (JAXA) have now released the first images captured by their Global Precipitation Measurement (GPM) Core Observatory satellite.

GPM soared to space on Feb. 27, exactly one month ago, during a spectacular night launch from the Japanese spaceport at the Tanegashima Space Center on Tanegashima Island off southern Japan.

The newly released series of images show precipitation falling inside a vast extra-tropical cyclone cascading over a vast swath of the northwest Pacific Ocean, approximately 1,000 miles off the coast of eastern Japan.

3D view inside an extra-tropical cyclone observed off the coast of Japan, March 10, 2014, by GPM's Dual-frequency Precipitation Radar. The vertical cross-section approx. 4.4 mi (7 km) high show rain rates: red areas indicate heavy rainfall while yellow and blue indicate less intense rainfall.   Credit:  JAXA/NASA
3D view inside an extra-tropical cyclone observed off the coast of Japan, March 10, 2014, by GPM’s Dual-frequency Precipitation Radar. The vertical cross-section approx. 4.4 mi (7 km) high show rain rates: red areas indicate heavy rainfall while yellow and blue indicate less intense rainfall. Credit: JAXA/NASA

“It was really exciting to see this high-quality GPM data for the first time,” said GPM project scientist Gail Skofronick-Jackson at NASA’s Goddard Spaceflight Center in Greenbelt, Md., in a NASA statement.

“I knew we had entered a new era in measuring precipitation from space. We now can measure global precipitation of all types, from light drizzle to heavy downpours to falling snow.”

The imagery was derived from measurements gathered by GPM’s two advanced instruments: JAXA’s high resolution dual-frequency precipitation (DPR) radar instrument (Ku and Ka band), which imaged a three-dimensional cross-section of the storm, and the GPM microwave imager (GMI) built by Ball Aerospace in the US which observed precipitation across a broad swath.

“The GMI instrument has 13 channels that measure natural energy radiated by Earth’s surface and also by precipitation itself. Liquid raindrops and ice particles affect the microwave energy differently, so each channel is sensitive to a different precipitation type,” according to a NASA statement.

On March 10, 2014 the Global Precipitation Measurement (GPM) Core Observatory passed over an extra-tropical cyclone about 1,055 miles (1,700 km) east of Japan's Honshu Island. Formed when a cold air mass wrapped around a warm air mass near Okinawa on March 8, it moved NE drawing cold air over Japan before weakening over the North Pacific.   Credit:  NASA/JAXA
On March 10, 2014 the Global Precipitation Measurement (GPM) Core Observatory passed over an extra-tropical cyclone about 1,055 miles (1,700 km) east of Japan’s Honshu Island. Formed when a cold air mass wrapped around a warm air mass near Okinawa on March 8, it moved NE drawing cold air over Japan before weakening over the North Pacific. Credit: NASA/JAXA

The 3850 kilogram GPM observatory is the first satellite designed to measure light rainfall and snow from space, in addition to heavy tropical rainfall.

The data were released following check out and activation of the satellites pair of instruments.

“GPM’s precipitation measurements will look like a CAT scan,” Dr. Dalia Kirschbaum, GPM research scientist, told me during a prelaunch interview with the GPM satellite in the cleanroom at NASA’s Goddard Space Flight Center in Greenbelt, Md.

“The radar can scan through clouds to create a three dimensional view of a clouds structure and evolution.”

The $933 Million GPM observatory will provide high resolution global measurements of rain and snow every 3 hours. It is a joint venture between NASA and JAXA.

It will collect a treasure trove of data enabling the most comprehensive measurements ever of global precipitation – and across a wide swath of the planet where virtually all of humanity lives from 65 N to 65 S latitudes.

The GMI instrument has 13 channels, each sensitive to different types of precipitation. Channels for heavy rain, mixed rain and snow, and snowfall are displayed of the extra-tropical cyclone observed March 10, off the coast of Japan. Multiple channels capture the full range of precipitation. Credit: NASA/JAXA
The GMI instrument has 13 channels, each sensitive to different types of precipitation. Channels for heavy rain, mixed rain and snow, and snowfall are displayed of the extra-tropical cyclone observed March 10, off the coast of Japan. Multiple channels capture the full range of precipitation. Credit: NASA/JAXA

GPM orbits at an altitude of 253 miles (407 kilometers) above Earth – quite similar to the International Space Station (ISS).

GPM is the lead observatory of a constellation of nine highly advanced Earth orbiting weather research satellites contributed by the US, Japan, Europe and India.

NASA’s next generation Global Precipitation Measurement (GPM) observatory inside the clean room at NASA Goddard Space Flight Center, MD. Technicians at work on final processing during exclusive up-close inspection tour by Universe Today.  GPM is slated to launch on February 27, 2014 and will provide global measurements of rain and snow every 3 hours. Credit: Ken Kremer/kenkremer.com
NASA’s next generation Global Precipitation Measurement (GPM) observatory inside the clean room at NASA Goddard Space Flight Center, MD. Technicians at work on final processing during exclusive up-close inspection tour by Universe Today. GPM launched on February 27, 2014 and will provide global measurements of rain and snow every 3 hours. Credit: Ken Kremer/kenkremer.com

Stay tuned here for Ken’s continuing GPM, Curiosity, Opportunity, Chang’e-3, SpaceX, Orbital Sciences, LADEE, MAVEN, MOM, Mars and more planetary and human spaceflight news.

Learn more at Ken’s upcoming presentations at the NEAF convention on April 12/13 and at Washington Crossing State Park, NJ on April 6. Also at the Quality Inn Kennedy Space Center, Titusville, FL, March 29.

Ken Kremer

Event Alert: Watch Space Station Hatch Opening Live Tonight

The Expedition 39/40 crew just before climbing into their Soyuz spacecraft in Kazakhstan on March 25, 2014. From top, Oleg Artemyev (Roscosmos), Steve Swanson (NASA) and Alexander Skvortsov (Roscosmos). Credit: NASA/Joel Kowsky

Update, 8:33 p.m. EDT: The Soyuz spacecraft arrived safely at station at 7:53 p.m. EDT (11:53 a.m. UTC) and coverage of the hatch opening is scheduled at 10:15 p.m. EDT (2:15 a.m. UTC).

After spending an extra couple of days in the cramped Russian Soyuz spacecraft, the incoming International Space Station crew will likely be very be glad to get out and stretch their legs. You can check out the festivities live in the video link above.

Three people are set to make a docking with the orbiting complex at 7:58 p.m. EDT (11:58 p.m. UTC). If all goes to schedule, they’ll pop the hatch open at 10:40 p.m. EDT (2:40 a.m. UTC). Meanwhile, engineers are trying to figure out what caused the malfunction that prevented a docking as planned on Tuesday (March 25).

Remember that all schedules are subject to change, so tune into NASA TV well before each event happens.

The Expedition 39/40 crew lifted off Tuesday afternoon (EDT) from Kazakhstan to take a fast track to the space station that should have seen them dock on launch day. The Soyuz has to make three engine firings or burns to accomplish this. The docking was cancelled after the third burn did not happen as planned. The Russian Federal Space Agency (Roscosmos) has determined this was because the spacecraft was in the wrong orientation, but the underlying cause is still being investigated.

Once this happened, the crew switched to a standard backup procedure to bring them to the station in two days instead. (This path, in fact, was what all crews did up until last year.) The crew is safe and in good spirits heading up to the docking, NASA has said. The Soyuz has done several other engine firings since, with no incident.

The Soyuz crew includes Steve Swanson (NASA), Alexander Skvortsov (Roscosmos) and Oleg Artemyev (Roscosmos). Awaiting them on the station are Koichi Wakata (Japan Aerospace Exploration Agency),  Rick Mastracchio (NASA) and Mikhail Tyurin (Roscosmos). Wakata is in command of the station, marking a first for Japan’s astronaut corps.

What Does the Grand Canyon Look Like from Space?

Image of the Grand Canyon from the International Space Station on March 26, 2014. Credit: NASA/JAXA Koichi Wakata.

Can you spot the Grand Canyon in this picture? It is surprisingly hard to see. Astronaut Koichi Wakata took this picture on March 26, 2014 from the International Space Station, and thankfully he provided a clue: look in the bottom center portion in the photo.

Astronaut Karen Nyberg also took a photo of the Grand Canyon last fall from the ISS, and this one offers a little better closeup:

If you’ve ever stood at this Canyon’s edge or even flew over in a plane, you know how dramatic the view is. From space … not so much.

You may have seen a fake image of the Grand Canyon from space floating around the various social medias last year that looks much more majestic. I won’t share it here, but suffice to say, it’s a doctored up aerial view with a starry sky photoshopped in. The images here are the real view of the Grand Canyon from space.

Earth’s Grand Canyon pales in comparison to Valles Marineris on Mars– the biggest canyon we know of in the Solar System — which is ten times longer and five times deeper than our Grand Canyon here on Earth.

In depth: Valles Marineris: The Grandest Canyon of All

Valles Marineris as seen in this mosaic of Viking orbiter images. Noctis Labyrinthus at the left, Melas Chasma in the middle, Hebes Chasma just left of top center, Eos Chasma at lower right and Ganges Chasma just above center right. Credit: NASA/JPL
Valles Marineris as seen in this mosaic of Viking orbiter images. Noctis Labyrinthus at the left, Melas Chasma in the middle, Hebes Chasma just left of top center, Eos Chasma at lower right and Ganges Chasma just above center right. Credit: NASA/JPL

Stunning 3D Tours of Two Well-Known Nebulae

Two videos recently released by the Hubble team take us on a tour of two famous and intriguing cosmic objects: the stellar wind-blown “celestial snow angel” Sharpless 2-106 and the uncannily equine Horsehead Nebula, imaged in infrared wavelengths by the HST.

Using Hubble imagery complemented with data from the Subaru Infrared Telescope and ESO’s Visible and Infrared Survey Telescope for Astronomy — VISTA, for short — the videos show us an approximation of the three-dimensional structures of these objects relative to the stars surrounding them, providing a perspective otherwise impossible from our viewpoint on Earth.

The stellar nursery Sharpless 2-106 is above; hop on the Horsehead Nebula tour below:
Continue reading “Stunning 3D Tours of Two Well-Known Nebulae”