14.07.2021

In the 1970s four spacecraft began their one-way trips out of our Solar System. As the first human-built objects to ever venture into interstellar space, NASA chose to place plaques on Pioneer 10 and 11 and golden records on Voyager 1 and 2 spacecraft to serve as messages to any alien spacefarers that may someday encounter these spacecraft. Continuing this legacy, NASA’s Lucy spacecraft will carry a similar plaque.  However, because Lucy will not be venturing outside of our Solar System, Lucy’s plaque is a time-capsule featuring messages to our descendants.

As the first-ever mission to the Trojan asteroids, Lucy will survey this enigmatic population of small bodies that orbit the Sun beyond the main asteroid belt - trapped by Jupiter and the Sun so that they have led and followed Jupiter in its orbit. As these never before explored asteroids are in many ways “fossils” from the formation and evolution of the planets, the Lucy spacecraft is named in honor of the fossilized human ancestor discovered the year after Pioneer 11 began its journey out of the Solar System. Lucy’s name was inspired by the Beatles’ song “Lucy in the Sky with Diamonds.”

After Lucy finishes visiting a record number of asteroids for a single mission in 2033 (8 asteroids on 6 independent orbits around the Sun) the Lucy spacecraft will continue to travel between the Trojan asteroids and the orbit of the Earth for at least hundreds of thousands, if not millions of years. It is easy to imagine that someday in the distant future our descendants will find Lucy floating among the planets. Therefore, the Lucy team chose to put a time-capsule aboard the Lucy spacecraft in the form of a plaque, messages this time not for unknown aliens, but for those that will come after us.  The plaque was installed on the spacecraft in a ceremony at Lockheed Martin Space in Littleton, Colorado, on July 9, 2021.

This time-capsule contains messages from prominent members of our society; individuals who have asked us to contemplate the state of the human condition as well as our place in the universe. These thoughtful leaders were asked to provide words of advice, words of wisdom, words of joy, and words of inspiration to those who may read this plaque in the distant future. These messages were solicited from Nobel Laureates in Literature, United States Poet Laureates, and other inspirational figures including the members of the band that indirectly inspired the Lucy mission’s name.

To date this time-capsule, the plaque also includes a depiction of the Solar System on the day of Lucy’s anticipated launch of October 16, 2021. The original trajectory of the Lucy spacecraft, traveling between the Trojan swarms and the Earth’s orbit, is shown as well.

NASA places this plaque with the hope that space exploration continues and someday astro-archeologists may travel among the planets and retrieve this spacecraft as an artifact of the early days when humanity took its first steps to explore our Solar System.

Southwest Research Institute in Boulder, Colorado is the principal investigator institution. NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems engineering and safety and mission assurance. Lockheed Martin Space in Littleton, Colorado is building the spacecraft. Lucy is the 13th mission in NASA’s Discovery Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Discovery Program for the agency’s Science Mission Directorate in Washington, D.C.

Quelle: NASA

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Update: 21.07.2021

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NASA’s Lucy Spacecraft Gets Shocked

Seen here in March 2021, NASA’s Lucy spacecraft undergoes its Clampband Shock Test at Lockheed Martin Space’s Littleton, Colorado, facility. This activity simulates the release of Lucy from the launch vehicle and ensures the spacecraft can withstand the shock generated by that event. Credit: Lockheed Martin

A Lockheed Martin technician makes sure a solar array on NASA’s Lucy spacecraft is secured during the Clampband Shock Test in March 2021. The test mimics the separation of the band connecting Lucy to its launch vehicle – the last major thing to happen before Lucy is on its own in space. Credit: Lockheed Martin

Quelle: NASA

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NASA's Lucy spacecraft has San Antonio ties and rock 'n' roll friends

My 82-year-old mother wasn’t thrilled to visit Meteor Crater outside Winslow, Ariz., last summer. She wondered why we went out of our way to see the spectacle she dubbed “a big hole in the ground.”

Luckily, her skepticism didn’t dampen the rest of my family’s curiosity.

You see, 50,000 years ago, a 150-foot-wide iron-nickel meteorite weighing 300,000 tons slammed into the desert at 26,000 miles per hour with the force of more than 2½ tons of dynamite. The explosion created a crater 750 feet deep and almost a mile wide.

So, technically, yes, Mom was right — it is a big hole in the ground. But it’s much more than that.

Scientists are still learning from Meteor Crater. NASA astronauts trained there in the 1960s. And, of course, the oddity remains a summer road trip rite of passage with its handy location off Interstate 40 and the former Route 66.

Standing on the edge of the abyss makes you feel small, and on that bright June day, hot gusts of wind battered us on the observation deck. The desert air combined with the Arizona sun made us thirsty as we tried to fathom the forces that created the massive crater.

But this column isn’t really about Meteor Crater. It’s about NASA’s Lucy mission, rock ’n’ roll and the band Queen’s tie to the Southwest Research Institute, San Antonio’s nonprofit mega-lab.

Let’s pause for a quick refresher. Asteroids are rocky objects that orbit the sun; comets are balls of ice and dust that also orbit the sun; meteoroids are small pieces of asteroids or comets; meteors (aka “shooting stars”) are meteoroids that burn up as they enter Earth’s atmosphere; meteorites are meteors that don’t burn up completely and hit Earth.

Then there are asteroids and comets that come from other galaxies, but that’s a whole other issue.

So large meteor strikes on Earth are obviously a scary possibility. Thankfully, scientists around the world are hard at work studying the various things that could slam into our planet.

The United Nations-sanctioned Asteroid Day is an international forum raising awareness about asteroids’ role in the solar system’s formation and the importance of defending the planet against future impacts. Its tag line: “Find hazardous asteroids before hazardous asteroids find us. The dinosaurs never saw that asteroid coming. What’s our excuse?”

Held annually on June 30, Asteroid Day brings together experts to discuss their latest research. June 30 is also the anniversary of the Siberia Tunguska event, the largest meteor impact on Earth in modern history, which leveled 800 square miles of remote forest or roughly 80 million trees.

Eighty million trees!

Former Queen guitarist-turned-astrophysicist Brian May, Apollo 9 astronaut Rusty Schweickart and several others started Asteroid Day in 2015.

“Asteroid Day was created to encourage the public and governments to learn more about asteroids, the origin of our Solar System, and to support the resources necessary to find and deflect asteroids,” May said in a statement. “We have all seen how unprepared the human race was, faced with a pandemic. The threat of an asteroid strike is just as real. The consequences could be just as catastrophic.”

Here’s where San Antonio comes in.

Southwest Research Institute is leading NASA’s Lucy mission to study the Trojan asteroids. Hal Levison is the mission’s primary investigator, and Cathy Olkin is the deputy principal investigator. Both work out of SwRI’s Boulder, Colo., office. And engineers and scientists in SwRI’s San Antonio facility built several components for the scientific instruments aboard Lucy.

It’s the first mission to study the asteroid belt that’s in the same orbit around the sun as Jupiter. The spacecraft, which is as tall as a five-story building when its solar panels are extended, is set to blast off on its 4 billion-mile journey aboard an Atlas 5 rocket from Cape Canaveral in October.

Cathy Olkin talked about Lucy during last month’s Asteroid Day. The event was virtual due to the pandemic.

She said May helped the Lucy team with a special plaque that’ll be attached to the spacecraft.

“There’s been the idea of putting plaques on spacecraft in case someone discovers it in the future, and the Lucy mission is going to orbit for a very long time, you know — more than 1,000 years inside our solar system,” she said. “And so the idea for the plaque is that it’s a message to our descendants.”

Lucy’s name honors the “fossilized human ancestor discovered the year after Pioneer 11 began its journey out of the Solar System,” as well as the Beatles’ song “Lucy in the Sky with Diamonds.”

And, yes, words from the Beatles are also on the plaque.

After Lucy reaches space, it’ll orbit Earth twice before heading toward the Trojan asteroids. In 2025, it’ll pass an asteroid named “Donaldjohanson” between Mars and Jupiter.

“Donald Johanson is the paleoanthropologist who discovered the Lucy fossil in 1974,” Olkin said. “We named the asteroid that we’re going to fly by after him.”

She said that Lucy the fossil transformed our understanding of human evolution just as Lucy the spacecraft will transform our understanding of the solar system’s evolution.

Lucy won’t reach the first Trojan asteroid until 2027. When it does, it’ll be the first time for humanity.

“Every time we see objects for the first time, we learn so much more — we learn even about questions we didn’t know to ask previously,” she said. “I’m really looking forward to visiting different types of asteroids and trying to understand why they look different and what made them that way.”

Lucy is slated to fly by five Trojan asteroids in 2027 and 2028. The craft will rendezvous with another two Trojan asteroids in 2033 and then will maintain an orbit for thousands of years.

“This is a great time to be exploring our solar system,” Olkin said. “There’s so many interesting NASA missions.”

Lucy is another example of how San Antonio is contributing to space exploration. The things Lucy learns could help save us all someday.

Oh, and even though she won’t admit, I think my mom secretly enjoyed the visit to Meteor Crater.

Quelle: MYSA

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Update: 30.07.2021

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Lucy spacecraft passes pre-shipment review, on track for October launch

NASA and Lockheed Martin are another step closer to the launch of their Lucy Trojan Explorer mission, with the craft completing its pre-shipment review ahead of transportation to the Cape Canaveral Space Force Station in Florida in August.

Lucy will be the first mission of its kind, set to explore several asteroids in Jupiter’s L4 and L5 Lagrange points. The craft is targeted to launch on a United Launch Alliance (ULA) Atlas V 401 rocket no earlier than October 16, 2021 at 05:35 EDT from SLC-41.

The Lucy interplanetary spacecraft is part of NASA’s Discovery program. Originally proposed in May 2014, Lucy became a finalist in 2015 alongside Psyche, DAVINCI, VERITAS, and NEOCam. In January 2017, Lucy and Psyche were chosen as the 13th and 14th Discovery missions, respectively. DAVINCI and VERITAS were later selected in a follow-on Discovery program competition as the 15th and 16th missions in June 2021. NEOCam was also ultimately selected to fly by NASA in 2021 but not as part of the Discovery program.

Soon after being selected, the Lucy team began finalizing the design of the spacecraft. In October 2018, NASA approved the preliminary design review and a year later also approved the critical design review. This allowed the manufacturer, Lockheed Martin, to begin assembly and testing of the spacecraft.

Lucy was built at the Lockheed Martin Waterton facility in Colorado, incorporating lessons learned from the prior builds of the New Horizons and OSIRIS-REx spacecrafts. The three science instruments Lucy will carry were derived from those two prior missions.

Assembly of Lucy. Credit: Lockheed Martin

Lucy’s LOng Range Reconnaissance Imager (L’LORRI) is a high spatial resolution visible imager based on the LORRI instrument used on New Horizons. L’LORRI will provide highly detailed images of the Trojan asteroid surfaces. It was built by the Johns Hopkins University Applied Physics Laboratory.  

Similarly, Lucy’s Thermal Emission Spectrometer (L’TES) will detect radiation emitting from the Trojan asteroids. It is based on the OTES (OSIRIS-REx Thermal Emission Spectrometer) used on OSIRIS-REx and the EMIRS (Emirates Mars Infrared Spectrometer) used on the Al-Amal Mars mission; it was built by Arizona State University. 

The third and final instrument is L’Ralph, which is made of two sub-instruments: the Multispectral Visible Imaging Camera (MVIC), a collar visible imager, and the Linear Etalon Imaging Spectral Array (LEISA), an infrared spectrometer. L’Ralph is based on the Ralph instrument flown on New Horizons and will be used to measure silicates, ice, and organics on the surface of the Trojan asteroids. It was built by the Goddard Space Flight Center. 

The spacecraft will also use its radio telecommunications hardware and high-gain antenna to measure doppler shifts that will help determine the mass of the Trojans.

Once fully fueled, Lucy will have a launch mass of 1,550 kg. The body of the spacecraft is 14.25 m in width and 7.2 m in height. The spacecraft will also use twin 7.3 m diameter circular solar arrays as part of its power system. A 2-meter diameter high gain antenna will be used to communicate with Earth. 

Image of Lucy’s plaque. Credit: SWRI

Lucy will also carry a special message. Known as the “Lucy Plaque,” this element of the mission will be used as a time capsule, carrying messages and diagrams. It will be similar to the “Pioneer plaque” used on the Pioneer 10 and 11 spacecraft.

Main assembly of Lucy was completed in February 2021, with teams then transitioning to thermal vacuum, vibration and shock, and electromagnetic testing. In April 2021, Lucy stretched its wings in a successful solar array deployment test. 

With those test complete, Lucy passed its pre-shipment review in July 2021 and is in processing for delivery to Cape Canaveral in August. Once at the launch site, it will undergo final testing and fueling before being placed in the Atlas V’s 4.2-meter diameter payload fairing.

Lucy will be launched from CCSFS SLC-41 on an Atlas V 401 rocket. The Atlas V is United Launch Alliance’s workhorse: a two-stage to orbit rocket consisting of an Atlas Common Core Booster powered by a single Russian RD-180 engine and the Centaur III upper stage powered by a single RL-10.

Once in its fairing, Lucy will be placed on top of the Atlas V rocket. Launch is currently set for no earlier than October 16, 2021, the beginning of a 21-day launch window that ends on November 5.

Lucy’s mission

Following launch, Lucy will perform two gravity assist flybys of Earth in 2022 and 2024 to kick off its 12 year mission throughout the solar system. These flybys will put Lucy on the correct trajectory to intercept all seven of the asteroids it is expected to study. After completing the second Earth flyby, Lucy will be on the correct trajectory to flyby the first set of Trojan asteroids located at Jupiter’s L4 Lagrange point.

The planned orbit for Lucy. Credit: NASA

However, before performing its L4 asteroid flybys, Lucy will first flyby asteroid 52246 Donaldjohanson. 52246 Donaldjohanson is a main-belt asteroid that’s 4 km in diameter and located in the primary asteroid belt between the orbits of Mars and Jupiter. Lucy will use 52246 Donaldjohanson as a rehearsal for its flybys of the Trojans — just as New Horizons used Jupiter as a practice target ahead of its eventual encounter with Pluto. 

Although it may be used as a rehearsal, 52246 Donaldjohanson will provide valuable data on the C-type asteroid, which has been identified as a fragment of a massive collision 130 million years ago which formed the Erigone family of asteroids that 52246 Donaldjohanson is a part of. 

Lucy is currently expected to flyby the asteroid on April 20, 2025.

After performing the flyby, Lucy will coast through interplanetary space for two years before arriving at the L4 “swarm” of Trojan asteroids in 2027. 

The groups of asteroids located at Jupiter’s Lagrange points are described as “swarms” due to each asteroid’s close proximity to another. The L4 swarm is known as the “Greek camp” of Trojan asteroids due to most of the asteroids being named after Greek heroes in the Trojan war or from around the same time period.

Once at the L4 swarm, Lucy will prepare for flybys of four Trojan asteroids. The first flyby, set to take place on August 12, 2027, will bring Lucy to asteroid 3548 Eurybates. Eurybates is 64 km in diameter and classified as a C-type asteroid. Like 52246 Donaldjohanson, Eurybates is part of a collisional family in the Greek camp. 

Eurybates also has a tiny, 1 km in diameter satellite named Queta which will be studied as well.

Eurybates is an interesting target as it is a C-type asteroid, which are quite rare in the Trojan families while being common in the main belt.

A little over a month after its flyby of Eurybates and Queta, Lucy will flyby asteroid 15094 Polymele. Polymele will be the smallest Trojan visited, at just 21 km in diameter. Like the final two Trojans Lucy will visit, Polymele is a P-type asteroid with a low albedo, a featureless reddish spectrum, possible organic rich silicates, carbon and anhydrous silicates, and possibly water ice in its interior. 

Lucy’s flyby of Polymele will mark the first time a spacecraft has visited a P-type asteroid. Scientists currently believe Polymele may be a fragment of a collision between an object and a larger P-type asteroid. Lucy’s flyby of Polymele is currently planned for September 15, 2027.

Artist impression of Lucy’s targets. Credit: NASA

The craft will then coast through the Greek camp L4 swarm Trojans for 7 months, culminating on April 18, 2028 with a flyby of  asteroid 11341 Leucus — its 3rd L4 Trojan asteroid flyby. 

Leucus is a D-type asteroid that is 34 km in diameter. Scientists plan to compare Leucus to the other D-type asteroids Lucy will visit to understand what materials make up this class of dark red asteroids. Leucus itself is likely quite elongated in shape, as its brightness fluctuates when observed from Earth. 

Lucy may also provide answers to why Leucus rotates as slowly as it does — once every 19.4 days (466 hours).

The final asteroid in the L4 swarm to be visited by Lucy will be 21900 Orus, another D-type asteroid. Lucy is expected to pass the 51 km diameter asteroid on November 11, 2028, a little less than six months after its flyby of Leucus.

At this point, Lucy will exit Jupiter’s L4 point and begin a coast-phase toward Earth, performing a gravity-assist with the planet in December 2030 to send it on a trajectory to Jupiter’s L5 point. When it arrives at the L5 Trojan swarm, known as the “Trojan camp,” in 2033, it will examine its final two Trojan asteroids in a single flyby.

The binary pair 617 Patroclus and Menoetius orbit one another with a separation of 680 km. Patroclus is 113 km in diameter while Menoetius is slightly smaller at 104 km. Both Trojans are P-type asteroids, similar to the L4 Trojan Polymele, which Lucy will have visited 6 years earlier at this point.

Scientists currently believe the two Trojans are primordial asteroids, leftover material from the formation of the solar system. Lucy is currently planned to flyby 617 Patroclus and Menoetius on March 2, 2033. At this point, the original mission will end.

At the completion of Lucy’s mission, the daring spacecraft will become the only mission in history to visit 8 different locations (Earth, Donaldjohanson, Eurybates, Polymele, Leucus, Orus, Patroclus, and Menoetius) in a single mission.