The DownlinkMay 07, 2021

Saving the World One Asteroid at a Time

Space Snapshot

Jupiter comet impact scars

This image from NASA’s Hubble Space Telescope reminds us of the importance of defending the Earth from impacts. The brown areas in this image of Jupiter taken in July 1994 are the scars of a series of impacts by fragments of comet Shoemaker-Levy 9. The main impact area is about 2,500 kilometers (1,550 miles) in diameter. Image credit: H. Hammel/MIT/NASA/J. Schmidt.

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Fact Worth Sharing

Jupiter illustration

Jupiter has been called the vacuum cleaner of the solar system because its gravity sucks in asteroids and comets, protecting us from those objects. But it's not all good: Jupiter's gravity can also nudge an object onto an orbital collision course with Earth.

Mission Briefings

Long march 5b rocket

A large rocket stage is tumbling uncontrollably back to Earth. On April 29, China launched Tianhe—the core module for its new space station—on a Long March 5B rocket (pictured). Though the launch successfully sent Tianhe to its planned destination, the 30-meter-long (100 feet) core stage failed to deorbit itself safely. Experts are now predicting an uncontrolled reentry somewhere as far north as New York and as far south as New Zealand, sometime between May 8 and 10. Most likely pieces of the core stage will wind up in the ocean, but rocket debris could cause some sort of damage on the ground. Unlike asteroid impacts where nobody is at fault, there is legal precedent for China to face consequences if any damage results from this uncontrolled reentry. Image credit: CGTN.


NASA has instructed SpaceX to stop working on the lunar lander it's developing for the agency. The order comes after Blue Origin and Dynetics filed protests challenging NASA’s decision to award its multi-billion-dollar Human Landing System contract to SpaceX. SpaceX must pause work related to the contract until the Government Accountability Office makes a ruling, which is expected to be no later than August 4. This doesn't stop the company from testing its Starship vehicle, which landed successfully following a test flight on May 5. Meanwhile, Blue Origin recently announced the first tourism flight on board its New Shepard spacecraft will take place July 20.


Space was recently in focus in Washington, D.C. Last week Planetary Society president Bethany Ehlmann testified before the U.S. House of Representatives Committee on Science, Space, and Technology. Along with three other Mars scientists, Ehlmann answered the question posited in the title of the hearing: "What Do Scientists Hope to Learn with NASA’s Mars Perseverance Rover?" Also this week, Bill Nelson officially became the newest NASA administrator. On May 3, Nelson was sworn in by Vice President Kamala Harris, making the former Florida senator NASA’s 14th administrator.


NASA’s Ingenuity helicopter successfully completed its fourth flight. Ingenuity project manager MiMi Aung said the Mars ’copter saved more images than it had on previous flights—about 60 images in the last 50 meters (about 164 feet) before landing back on the Red Planet.


Crew-1 astronauts are back on Earth after a historic nighttime splashdown. NASA astronauts Michael Hopkins, Victor Glover, and Shannon Walker, along with JAXA astronaut Soichi Noguchi, splashed down in the Gulf of Mexico in a SpaceX Crew Dragon capsule. The last nighttime splashdown of a crewed U.S. spacecraft was Apollo 8’s return in 1968.

From The Planetary Society

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Planetary Society logo bullet

Calling all asteroid hunters, scientists, and engineers! The Planetary Society is currently soliciting proposals for two science and technology grant programs.

Our Shoemaker NEO grant program funds amateur and professional observers throughout the world who make vital contributions to our understanding of the asteroid threat by scanning the skies for asteroids, tracking or characterizing known objects, and otherwise contributing to the hunt for dangerous asteroids. Take a look at our request for proposals to learn more.

If you have an idea that could change the future of space, check out our newest grant program: Science and Technology Empowered by the Public (STEP). STEP grants are competitively awarded through an open, international process. If you or your organization have an innovative idea related to exploring other worlds, finding life, or defending Earth from dangerous asteroids, submit a pre-proposal by May 26, 2021.

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Has all this talk of saving the world got you jazzed up? You may want to dive into Andy Weir’s latest book. The author of The Martian and Artemis has just published Project Hail Mary, an exciting and inventive story of an unlikely protagonist tasked with saving humanity. Weir joined this week’s Planetary Radio to talk about the book and much more.

What's Up

Jupiter illustration

The five planets visible with the naked eye are all up this week. In the evening look for Mercury low in the evening west, with Venus even lower to the horizon. Mars also shines in the evening sky, higher in the west. Before dawn, catch Jupiter and Saturn in the east. Learn more at

Take Action to Defend Earth

Neo art

The threat of asteroid impacts is very real, but it isn’t an inevitability. Humans have the capabilities needed to protect our planet from cosmic devastation—we just need to mobilize them. You can help make a difference.

U.S. residents can petition Congress and the White House to support NASA’s planetary defense efforts. If you live elsewhere, we encourage you to find the contact information for your government representative(s) and tell them about the importance of planetary defense and the steps that need to be taken by all nations of the world.

Next, take direct action to support the hunt for dangerous asteroids by donating to our Shoemaker NEO Grant program. With your help, we can defend our planet from the hazards of the cosmos.

Wow of the Week

Jupiter lightning artist concept

What does lightning have in common with comets and asteroids? They all strike in Jupiter’s clouds. Scientists are still learning what causes lightning on Jupiter, one of the many fascinating facets of the giant world. This artist's conception by the creator of Griffith Observatory’s All Space Considered program shows lightning illuminating the Jovian cloud tops. White clouds of ammonia-ice rise above the reddish ammonium hydrosulfide clouds below. Europa and Io hang in the sky as the distant sun rises. Image credit: Patrick So/Griffith Observatory.