Posted on by Ken Kremer

First Ever Whole Sun View .. Coming Soon from STEREO

On Super Bowl SUNday - Feb 6, 2011; the two NASA STEREO spacecraft willl see the entire Sun ! Superbowl SUNday will truly mark a milestone for solar observations. On Ferbruary 6, the two STEREO spacecrafts will be 180 degrees apart and for the next 8 years the STEREO spacecrafts and SDO will be able to observe the entire 360 degrees of the Sun. Credit: NASA. Watch the cool STEREO Whole Sun Preview Video below. Plus Launch Video and more photos below.

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“For the first time in the history of humankind we will be able to see the front and the far side of the Sun … Simultaneously,” Madhulika Guhathakurta told Universe Today. Guhathakurta is the STEREO Program Scientist at NASA HQ.

Courtesy of NASA’s solar duo of STEREO spacecraft.

And the noteworthy event is timed to coincide just perfectly with ‘Super Bowl SUNday’ – Exactly one week from today on Feb. 6 during Super Bowl XLV !

“This will be the first time we can see the entire Sun at one time,” said Dean Pesnell, NASA Solar Astrophysicist in an interview for Universe Today. Pesnell is the Project Scientist for NASA’s Solar Dynamics Observatory at the NASA Goddard Spaceflight Center in Greenbelt, MD.

This remarkable milestone will be achieved when NASA’s two STEREO spacecraft reach position 180 degrees separate on opposite sides of the Sun on Sunday, Feb. 6, 2011 and can observe the entire 360 degrees of the Sun.

“We are going to celebrate by having a football game that night!” Pesnell added in jest.

The nearly identical STEREO spacecraft – dubbed STEREO Ahead and STEREO Behind – are orbiting the sun and providing a more complete picture of the Suns environment with each passing day. One probe follows Earth around the sun; the other one leads the Earth.

STEREO is the acronym for Solar TErrestrial RElations Observatory. Their mission is to provide the very first, 3-D “stereo” images of the sun to study the nature of coronal mass ejections.

Today, (Jan 30) the twin STEREO spacecraft are 179.1 degrees apart and about 90 degrees from Earth, and thus virtually at the midpoint to the back of the sun. See the orbital location graphics above and below.

Both probes were flung into space some four years ago and have been hurtling towards this history making date and location ever since. The wedge of unseen solar territory has been declining.

As the STEREO probes continue flying around to the back side of the sun, the wedge of unseen solar territory on the near side will be increasing and the SDO solar probe will play a vital gap filling role.

“SDO provides the front side view of the sun with exquisite details and very fast time resolution,” Gutharka told me. For the next 8 years, when combined with SDO data, the full solar sphere will still be visible.

The Whole Sun will be simultaneously Imaged for the First tIme ever on Super Bowl SUNday Feb. 6.
For the past 4 years, the two STEREO spacecraft have been moving away from the Earth and gaining a more complete picture of the sun. On February 9, 2011, NASA will hold a press conference to reveal the first ever images of the entire sun and discuss the importance of seeing all of our dynamic star.
Credit: NASA

The solar probes were launched together aboard a Delta II rocket from Launch Complex 17B at Cape Canaveral Air Force Station (CCAFS) in Florida on October 25, 2006. See Launch Video and Photos below.

Whole Solar Sphere A Goldmine for Science

I asked Pesnell and Guhathakurta to explain why this first ever whole Sun view is a significant scientific milestone.

“Until now there has always been an unseen part of the Sun,” Pesnell explained. “Although that unseen part has always rotated into view within a week or two, a global model must include all of the Sun to understand where the magnetic field goes through the surface.”

“Also, from the Earth we can see only one pole of the Sun at a time, while with STEREO we can see both poles at the same time.

“The next few years of overlapping coronal images will be a goldmine of information for predicting space weather at the Earth and understanding of how the Sun works. It is like getting the GOES images of the Earth for the first time. We haven’t missed a hurricane since, and now we won’t miss an active region on the Sun,” said Pesnell.

How will the science data collected be used to understand the sun and its magnetic field?

“Coronal loops trace out the magnetic field in the corona,” Pesnell elaborated. “Understanding how that magnetic field changes requires seeing where on the surface each loop starts and stops.”

Why is it important to image the entire Sun ?

“Once images of the entire Sun are available we can model the entire magnetic field of the Sun. This has become quite important as we are using STEREO and SDO to study how the entire magnetic field of the Sun reacts to the explosions of even small flares.”

“By seeing both poles we should be able to understand why the polar magnetic field is a good predictor of solar activity,” said Pesnell.

“Seeing both sides will help scientists make more accurate maps of global coronal magnetic field and topology as well as better forecasting of active regions – areas that produce solar storms – as they rotate on to the front side. Simultaneous observations with STEREO and SDO will help us study the sun as a complete whole and greatly help in studying the magnetic connectivity on the sun and sympathetic flares, ” Guhathakurta amplified.

Latest EUVI Images from STEREO. These Extreme Ultra Violet Images from STEREO Ahead and Behind were taken on Jan. 30, 2011. Credit: NASA

Watch a solar rotation animation here combining EUVI and SDO/AIA:

What is the role and contribution of NASA’s SDO mission and how will SDO observations be coordinated with STEREO?

“As the STEREO spacecraft drift around the Sun, SDO will fill in the gap on the near of the Sun,” explained Pesnell. “For the next 4 or more years we will watch the increase in sunspots we call Solar Cycle 24 from all sides of the Sun. SDO has made sure we are not doing calibration maneuvers for a few days around February 6.”

“On Feb 6th we will view 100% of the sun,” said Guhathakurta.

At a press conference on Feb. 9, 2011, NASA scientists will reveal something that no one has even seen – The first ever images of ‘The Entire Sun’. All 360 degrees

Watch the briefing on NASA TV at 2 PM EST

More about the SDO mission and SDO science
and Coronal holes from STEREO and SDO here

STEREO Website

“3D Sun”
A STEREO Movie in Digital and IMAX was released in 2007
Watch the way cool 3D IMAX trailer below

STEREO spacecraft location map

Caption: Positions of STEREO A and B for 31-Jan-2011 05:00 UT. The STEREO spacecraft are 179.2 degrees apart and about 90 degrees from Earth on Jan. 31, 2011. This figure plots the current positions of the STEREO Ahead (red) and Behind (blue) spacecraft relative to the Sun (yellow) and Earth (green). The dotted lines show the angular displacement from the Sun. Units are in A.U. (Astronomical Units). Credit: NASA

STEREO Launch Video

Launch Video Caption: The Delta II rocket lights the evening sky as STEREO heads into space on October 25, 2006 at 8:52 p.m. The Delta II rocket lights the evening sky as STEREO heads into space. STEREO (Solar Terrestrial Relations Observatory) is a multi-year mission using two nearly identical observatories, one ahead of Earth in its orbit and the other trailing behind. The duo will provide 3-D measurements of the sun and its flow of energy, enabling scientists to study the nature of coronal mass ejections and why they happen.

Fully fueled, technicians prepare the STEREO spacecraft for spin testing in the cleanroom in Titusville, Fl, while being prepared for launch. Credit: nasatech.net

Delta Launch Complex 17 comprises two launch pads and towers, 17 A & 17 B, at Cape Canaveral Air Force Station, FL. Credit: Ken Kremer
View of Delta II Launch Complex 17 by Ken Kremer

Fully clear of the smoke, STEREO streaks skyward during launch on October 25, 2006 from Pad 17B at Cape Canaveral, FL. Credit: nasatech.net

More STEREO Cleanroom and Launch photos from nasatech.net here

More about the SDO mission and SDO science
and Coronal holes from STEREO and SDO here

STEREO Website

“3D Sun”
A STEREO Movie in Digital and IMAX was released in 2007

Watch the way cool 3D trailer here – Trailer narrated by NASA’s Madhulika Guhathakurta
— be sure to grab hold of your Red-Cyan Glasses

Posted on by Nancy Atkinson

Challenger Astronauts Memorialized on the Moon

Craters in the center of Apollo basin named after Space Shuttle Challenger astronauts. Credit: NASA/GSFC/Arizona State University.

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Shortly after the loss of the Space Shuttle Challenger in 1986, seven craters on the eastern rim of the Apollo basin were named after the crew: Gregory Jarvis, Christa McAuliffe, Ronald McNair, Ellison Onizuka, Judith Resnik, Dick Scobee, Michael Smith. The Lunar Reconnaissance Orbiter Wide Angle Camera recently took this image of the region. Below is a video from the Kaguya spacecraft flying over the area.

According to OnOrbit, the crater “Onizuka” is incorrectly identified in this video. Rather, “Onizuka” is the crater next and to the right of the one labeled in the video as “The Onizuka”.

The Apollo Basin is not where I would have guessed — the area around the Moon’s equator on the near side where all the Apollo landings took place — but instead is a 524 km-diameter impact basin located within the center of the the giant South Pole-Aitken basin, (36°S, 209°E).

See more about the image and explore the entire region with LROC’s “zoomify” feature at the LRO website.

Posted on by Steve Nerlich

Astronomy Without A Telescope – Gravity Probe B

Gravity Probe B - testing the null hypothesis that the spin axis of a gyroscope should stay aligned with a distant reference point when it's in a free fall orbit. But Einstein says no.

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There’s a line out of an early episode of The Big Bang Theory series, where Gravity Probe B is described as having seen ‘glimpses’ of Einstein’s predicted frame-dragging effect. In reality, it is not entirely clear that the experiment was able to definitively distinguish a frame-dragging effect from a background noise created by some exceedingly minor aberrations in its detection system.

Whether or not this counts as a glimpse – frame-dragging (the alleged last untested prediction of general relativity) and Gravity Probe B have become linked in the public consciousness. So here’s a quick primer on what Gravity Probe B may or may not have glimpsed.

The Gravity Probe B satellite was launched in 2004 and set into a 650 kilometer altitude polar orbit around the Earth with four spherical gyroscopes spinning within it. The experimental design proposed that in the absence of space-time curvature or frame-dragging, these gyroscopes moving in a free fall orbit should spin with their axis of rotation unerringly aligned with a distant reference point (in this case, the star IM Pegasi).

To avoid any electromagnetic interference from the Earth’s magnetic field, the gyroscopes were housed within a lead-lined thermos flask – the shell of which was filled with liquid helium. This shielded the instruments from external magnetic interference and the cold enabled superconductance within the detectors designed to monitor the gyroscopes’ spin.

Slowly leaking helium from the flask was also used as a propellant. To ensure the gyroscopes remained in free fall in the event that the satellite encountered any atmospheric drag – the satellite could make minute trajectory adjustments, essentially flying itself around the gyroscopes to ensure they never came in to contact with the sides of their containers.

Now, although the gyroscopes were in free fall – it was a free fall going around and around a space-time warping planet. A gyroscope moving at a constant velocity in fairly empty space is also in a ‘weightless’ free fall – and such a gyroscope could be expected to spin indefinitely about its axis, without that axis ever shifting. Similarly, under Newton’s interpretation of gravity – being a force acting at a distance between massive objects – there is no reason why the spin axis of a gyroscope in a free fall orbit should shift either.

But for a gyroscope moving in Einstein’s interpretation of a steeply curved space-time surrounding a planet, its spin axis should ‘lean over’ into the slope of space-time. So over one full orbit of the Earth, the spin axis will end up pointing in a slightly different direction than the direction it started from – see the animation at the end of this clip. This is called the geodetic effect – and Gravity Probe B did effectively demonstrate this effect’s existence to within only a 0.5% likelihood that the data was showing a null effect.

But, not only is Earth a massive space-time curving object, it also rotates. This rotation should, theoretically, create a drag on the space-time that the Earth is embedded within. So, this frame-dragging should tug something that’s in orbit forward in the direction of the Earth’s rotation.

Where the geodetic effect shifts a polar-orbiting gyroscope’s spin axis in a latitudinal direction – frame-dragging (also known as the Lense-Thirring effect), should shift it in a longitudinal direction.

The expected outcome. Orbiting through warped space-time shifts the spin axis of an gyroscope. But the anticipated frame-dragging shift has proved difficult to detect.

And here is where Gravity Probe B didn’t quite deliver. The geodetic effect was found to shift the gyroscopes spin axis by 6,606 milliarcseconds per year, while the frame-dragging effect was expected to shift it by 41 milliarcseconds per year. This much smaller effect has been difficult to distinguish from a background noise arising from minute imperfections existing within the gyroscopes themselves. Two key problems were apparently a changing polhode path and larger than expected manifestation of a Newtonian gyro torque – or let’s just say that despite best efforts, the gyroscopes still wobbled a bit.

There is ongoing work to laboriously extract the expected data of interest from the noisy data record, via a number of assumptions which might yet be subject to further debate. A 2009 report boldly claimed that the frame-dragging effect is now plainly visible in the processed data – although the likelihood that the data represents a null effect is elsewhere reported at 15%. So maybe glimpsed is a better description for now.

Incidentally, Gravity Probe A was launched back in 1976 – and in a two hour orbit effectively confirmed Einstein’s redshift prediction to within 1.4 parts in 10,000. Or let’s just say that it showed that a clock at 10,000 km altitude was found to run significantly faster than a clock on the ground.

Further reading: The Gravity Probe B experiment in a nutshell.

Posted on by Nancy Atkinson

Ken Kremer on Today’s APOD

Opportunity at Santa Maria Crater Credit: Mars Exploration Rover Mission, NASA, JPL, Cornell; Image Processing: Marco Di Lorenzo, Kenneth Kremer

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Congrats to Universe Today writer Ken Kremer and his image processing partner Marco Di Lorenzo for their handiwork being featured on today’s Astronomy Picture of the Day. It’s one of their great images they have enhanced of the Opportunity Rover peering into its current location at Santa Maria Crater on Mars. Check it out on APOD!

Posted on by Carnival of Space

Carnival of Space 182

The Carnival of Space 182 is up at nextbigfuture

After a one month hiatus, the Carnival of Space is back. Nextbigfuture will be working with Universe today on the organization of the Carnival of Space. There are hosts signed up into April already.

This week Carnival of space has an animation video of the Mars moon Phobos, nuclear fusion for space propulsion, vacuum engineering, cataclysmic variables and much more.

Posted on by Matt Williams

Magnetic Energy

Magnetic Energy
Magnetic Energy Flow. Image Credit: dhost.info

[/caption]During the 19th century, one of the greatest discoveries in the history of physics was made by an Scottish physicist named James Clerk Maxwell. It was at this time, while studying the perplexing nature of magnetism and electricity, that he proposed a radical new theory. Electricity and magnetism, long thought to be separate forces, were in actuality closely associated with each other. That is, every electrical current has associated with it a magnetic field and every changing magnetic field creates its own electrical current. Maxwell went on to express this in a set of partial differential equations, known as Maxwell’s Equations, and form the basis for both electrical and Magnetic Energy.

In fact, thanks to Maxwell’s work, magnetic and electric energy are more appropriately considered as a single force. Together, they are what is known as electromagnetic energy – i.e. a form of energy that has both electrical and magnetic components. It is created when one runs a magnetic current through a wire or any other conducive material, creating a magnetic field. The magnetic energy generated can be used to attract other metal parts (as in the case in many modern machines that have moving parts) or can be used to generate electricity and store power (hydroelectric dams and batteries).

Since the 19th century, scientists have gone on to understand that many types of energy are in fact forms of electromagnetic energy. These include x rays, gamma rays, visible light (i.e. photons), ultraviolet light, infrared radiation, radio waves, and microwaves. These forms of electromagnetic energy differ from each other only in terms of the wavelength and frequency. Those forms which have shorter waves and higher frequencies tend to be the more harmful varieties, such as x-rays and gamma rays, while those that have longer waves and shorter frequencies, such as radio waves, tend to be more benign.

In mathematical terms, the equation for measuring the output of a magnetic field can be expressed as follows: V = L dI/dt + RI where V is volume, L is inductance, R is resistance, I is charge, dI represents change in charge, and dt represents change over time.

Here are some articles about Magnetic Energy written for Universe Today.
Behind the Power and Beauty of Northern Lights
Magnetic Fields in Inter-cluster Space: Measured at Last

If you’d like more info on Magnetic Energy, check out these articles:
Wikipedia Entry on Magnetic Energy
More info about magnetic energy

We’ve also recorded an entire episode of Astronomy Cast all about Magnetism. Listen here, Episode 42: Magnetism Everywhere.

Sources:
http://en.wikipedia.org/wiki/Magnetic_energy
http://en.wikipedia.org/wiki/James_Clerk_Maxwell
http://en.wikipedia.org/wiki/Maxwell%27s_equations
http://fi.edu/guide/hughes/10types/typesmagnetic.html
http://farside.ph.utexas.edu/teaching/em/lectures/node84.html
http://science.jrank.org/pages/2489/Energy-Magnetic-energy.html

Posted on by Matt Williams

How Satellites Work

GPS Satellite
According to a new proposal, GPS satellites may be the key to finding dark matter. Credit: NASA

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In 1957, the Soviet Union launched the world’s first satellite, known as Sputnik. This changed the course of world history and led the United States, their chief rival in the Space Race, to mount a massive effort of its own to put manned craft in orbit and land a man on the moon. Since then, the presence of satellites in our atmosphere has become commonplace, which has muted the sense of awe and wonder involved. However, for many, especially students studying in engineering and aerospace programs, the question of How Satellites Work is still one of vital importance.

Satellite perform a wide array of functions. Some are observational, such as the Hubble Space Telescope – providing scientists with images of distant stars, nebulas, galaxies, and other deep space phenomena. Others are dedicated to scientific research, particularly the behavior of organisms in low-gravity environments. Then there are communications satellites which relay telecommunications signals back and forth across the globe. GPS satellites offer navigational aid and tracking aides to people looking to transport goods or navigate their way across land and oceans. And military satellites are used to observe and monitor enemy installations and formations on the ground while also helping the airforce and navy guide their ordinance to enemy targets.

Satellites are deployed by attaching them to rockets which then ferry them into orbit around the planet. Once deployed, they are typically powered by rechargeable batteries which are recharged through solar panels. Other satellites have internal fuel cells that convert chemical energy to electrical energy, while a few rely on nuclear power. Small thrusters provide attitude, altitude, and propulsion control to modify and stabilize the satellite’s position in space.

When it comes to classifying the orbit of a satellite, scientists use a varying list to describe the particular nature of their orbits. For example, Centric classifications refer to the object which the satellite orbits (i.e. planet Earth, the Moon, etc). Altitude classifications determine how far the satellite is from Earth, whether it is in low, medium or high orbit. Inclination refers to whether the satellite is in orbit around the equatorial plane, the polar regions, or the polar-sun orbit that passes the equator at the same local time on every pass so as to stay in the light. Eccentricity classifications describe whether the orbit is circular or elliptical, while Synchronous classifications describe whether or not the satellite’s rotation matches the rotational period of the object (i.e. a standard day).

Depending on the nature of their purpose, satellites also carry a wide range of components inside their housing. This can include radio equipment, storage containers, camera equipment, and even weaponry. In addition, satellites typically have an on-board computer to send and receive information from their controllers on the ground, as well as compute their positions and calculate course corrections.

We have written many articles about satellites for Universe Today. Here’s an article about the satellites in space, and here’s an article about exploring satellites with Google Earth.

If you’d like more info on satellites, check out these articles:
National Geographics article about Orbital Objects
Satellites and Space Weather

We’ve also recorded an episode of Astronomy Cast about the space shuttle. Listen here, Episode 127: The US Space Shuttle.

Sources:
http://en.wikipedia.org/wiki/Satellite
http://en.wikipedia.org/wiki/List_of_orbits
http://www.gma.org/surfing/sats.html
http://science.howstuffworks.com/satellite5.htm
http://www.howstuffworks.com/satellite.htm

Posted on by Nancy Atkinson

Comet Tempel 1 Now in StardustNeXT’s Field of View

The first image of comet Tempel 1 taken by NASA's Stardust spacecraft is a composite made from observations on Jan. 18 and 19, 2011. The panel on the right highlights the location of comet Tempel 1 in the frame. On Valentine's Day (Feb. 14 in U.S. time zones), Stardust will fly within about 200 kilometers (124 miles) of the comet's nucleus. Image credit: NASA/JPL-Caltech

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It’s comet ahoy! for the Stardust spacecraft, which is on its way to a Valentine’s Day meetup with comet Tempel 1. The images above were taken on Jan. 18 and 19 from a distance of 26.3 million kilometers (16.3 million miles), and 25.4 million kilometers (15.8 million miles). On Feb. 14, Stardust will fly within about 200 kilometers (124 miles) of the comet’s nucleus and for the first time we’ll get a second closeup look at Tempel 1.

“We were there in 2005 with the Deep Impact spacecraft, said Stardust-NExT Project Manager Tim Larson, speaking on today’s 365 Days of Astronomy podcast, “and this is a golden opportunity. It’s the first time we’ve ever been able to revisit a comet on a second pass near the sun.”

Larson said this encounter will give provide important information about how the surface of the comets change with each passage near the sun and whether the changes in the comet are global or just specific to certain areas on the surface.

From the Deep Impact mission, we already know that comet Tempel 1 has a wide variety of features on its surface.

“We have found smooth areas that look like material flows,” Larson said,” there are rough, pitted areas, there are craters on the surface, which we don’t know if they’re impact craters or if they’re caused by material coming out from the inside of the comet. So this is a very interesting comet in terms of variety of terrain.”

NASA's Deep Impact probe hits Comet Tempel 1 (NASA)

The exciting part will be comparing ‘before and after’ images of Tempel 1.

The spacecraft will be able to take up to 72 images and store them on board. Larson said the images will be carefully timed to center them around the closest approach to the comet, providing the best possible resolution.

“We should be able to get around three dozen images that are at better than 80 meters per pixel resolution and our closest approach images should be down below 20 meters per pixel resolution,” he said. “That will be good enough to resolve a lot of the key features on the surface of the comet and start that process of comparison.”

Artists concept of the stardust spacecraft flying throug the gas and dust from comet Wild 2. Credit: NASA/JPL

The repurposed Stardust spacecraft that flew past comet Wild 2 and brought back samples has just enough fuel to carry out maneuvers for the upcoming Tempel 1 flyby.

Larson said the preparations in designing the flyby sequences and software are almost complete and are being tested, and now the team is eagerly looking at the daily optical navigation images.

“We’re tracking where the comet is relative to the spacecraft,” he said, “and that will feed into our trajectory correction maneuvers. We have three more of those left before we arrive at the comet, and those will be used to target the spacecraft to the desired flyby point.”

The TCMs will occur on January 31, February 7, and then the last fully designed TCM will occur on February 12, two days before arrival.

There are challenges to using a recycled spacecraft.

“The primary challenge is, first of all, designing a new mission that it can accomplish with the fuel that it has left,” Larson said. “And through some clever mission design using some carefully timed trajectory correction maneuvers and taking advantage of some Earth gravity assists, we were able to modify the trajectory of the spacecraft to get it close to Tempel 1. So that’s been the primary challenge, and along with that is conserving the fuel that we have on board and making sure that we have enough fuel left to finish off this mission. Beyond that, there have been a few challenges in terms of aging equipment on board the spacecraft, — the spacecraft will be 12 years old in early February, and it’s well beyond its design life. And although everything is generally healthy on board, we have had a couple of pieces of equipment that were starting to age, and starting to degrade slightly. So we switched over to backup equipment so we were on fresh, healthy equipment, and we still have functioning equipment as backups.”

The closest approach will occur at 8:30 pm Pacific Time on February 14, 2011, where the spacecraft will be about 200 kilometers (125 miles) away from the surface of the comet, which is the closest any spacecraft has been to the surface of a comet.

Posted on by Nancy Atkinson

Christa McAuliffe’s Legacy Goes On

Christa McAuliffe. Credit: Challenger's Lost Lessons

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Christa McAuliffe never had the chance to fulfill her dream of teaching from space and in the aftermath of the accident, her lesson plans were filed away by NASA with sadness and grief. The lessons were incomplete, unfinished, and most regrettably, they were never were taught. I wrote an article two-and-a-half years ago how NASA engineer Jerry Woodfill — the same endearing engineer from our series “13 Things That Saved Apollo 13” — had come across McAuliffe’s unfinished lesson plans by accident and worked for several months to resurrect them and give them new life with current technology. On this 25th anniversary of the Challenger accident, I wanted to remind our readers of this engaging story, and how the Challenger Centers for Space Science Education are now using McAuliffe’s lessons. The lessons are also available for any teacher, or anyone who wants to view or use them.

Also, the Challenger Centers offer a wonderful education resource and experience for young people. Please consider donating to their mission, started by the families of the Challenger astronauts lost in the accident. Your donation will honor the Challenger 7 heroes and help inspire the next generation.