Rosetta and Its Kin: A History of Comet and Asteroid Missions


This article was written by Elizabeth Howell for Read the original article, here.

As the Rosetta spacecraft closes out its historic mission with a descent to the surface of Comet 67P/Churyumov-Gerasimenko tomorrow morning (Sept. 30), the European orbiter joins a long list of cometary and small-body missions that have helped scientists learn more about the early solar system.

Rosetta’s last moments will be broadcast live early tomorrow via several European Space Agency (ESA) channels, and NASA will air its own landing webcast as well. You can follow the action live here at, courtesy of NASA TV.

Here’s a brief look back at the Rosetta mission and other spacecraft that blazed, or are currently blazing, trails to asteroids and comets around the solar system. [Rosetta Probe’s ‘Death Dive’ Into Comet 67P Visualized (Video)]

The Rosetta orbiter and its piggyback lander, Philae, launched in March 2004, embarking on a decade-long journey to Comet 67P/Churyumov-Gerasimenko. Rosetta arrived at 67P in August 2014, becoming the first mission ever to orbit a comet.

In November 2014, the washing-machine-size Philae made its descent to 67P’s surface. Things did not go as planned; Philae’s securing harpoons failed to fire, and the lander bounced twice, spending several hours drifting above the surface.

When Philae finally came down for good, the area it landed in was so shady that its batteries could not recharge. Philae performed about 60 hours of work on the surface and made only sporadic contact with the Rosetta orbiter thereafter. The mothership, meanwhile, moved between different orbits above the comet and took high-resolution pictures of the surface. (Philae’s landing site remained unknown until Rosetta descended closer to the surface in early September and captured the lander in a photo.)

The two spacecraft made several key discoveries at 67P. The type of water on the comet is different than that found on Earth, suggesting that asteroids, or at least comets unlike 67P, may have brought most of the water to our planet. The Rosetta team also found organic compounds — the carbon-containing building blocks of life — on 67P’s surface.

Furthermore, Rosetta also provided an unprecedented close-up view of a comet’s changing activity as it drew closest to the sun, and then pulled away. Such observations can help researchers improve their predictions of cometary activity in the future, mission team members have said. [Rosetta’s Amazing Comet Mission in Pictures]

NASA launched an asteroid-sampling mission earlier this month, just three weeks before Rosetta’s grand finale.

The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer, or OSIRIS-REx, spacecraft lifted off on Sept. 8 and is now journeying toward a near-Earth asteroid called Bennu. If all goes according to plan, OSIRIS-REx will arrive at Bennu in 2018, nab a sample of asteroid material in 2020 and return that sample to Earth in September 2023.

The mission should help scientists better understand the role asteroids may have played in bringing life’s building blocks to Earth, NASA officials have said.

NASA’s Deep Impact spacecraft launched in January 2005 for Comet Tempel 1, with the aim of sending an impactor probe into the comet to learn more about its interior structure. The impactor was successfully fired on July 4, 2005, and Deep Impact took images from above.

The resulting crater showed that the comet contained more dust than previously expected (especially because the impact itself created a large dust cloud, which came as a surprise). Deep Impact was the first spacecraft ever to excavate material from a comet.

After its primary mission was complete, Deep Impact was redesignated EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) and began an extended mission. At first, investigators tried to fly the probe by Comet Boethin, but when it came time to refine EPOXI’s trajectory, the comet vanished — presumably because it had broken up into smaller pieces. So, instead, EPOXI flew by Comet Hartley 2 in November 2010 and did long-range observations of Comet Garradd and Comet C/2012 S1 (ISON).

NASA lost contact with the probe in September 2013, likely because of a software malfunction. When EPOXI was lost, it was en route to asteroid 163249 2002GT, with a scheduled 2020 rendezvous.


This NASA probe launched in February 1999 to collect samples from the coma of Comet Wild 2 and send them back to Earth. While flying to the comet, the spacecraft also passed by asteroid 5535 Annefrank.

Stardust’s return capsule arrived safely on Earth in 2006, while the probe continued operations in space. Its mission extension, called NExT (New Exploration of Tempel 1), passed by Comet Tempel 1 in February 2011. This extended the observations previously done by Deep Impact in 2005. NExT, low on fuel, had its transmitter switched off in March 2011, ending the mission.

The particles from Stardust have been analyzed repeatedly over the past decade. This work yielded a surprising find in 2014: Some of the particles that were collected were possibly bits of interstellar dust.


The Giotto and Vega missions, which were mounted by Europe and the Soviet Union, respectively, were the first to perform up-close observations of a comet: Comet Halley, which passes by the Earth every 75 or 76 years.

Giotto launched in July 1985 and made a close pass of Halley in March 1986. While it was in the comet’s neighborhood, Giotto was pummeled by debris — including one piece that knocked the spacecraft so it temporarily was not pointing its antenna at Earth. The camera was also lost due to debris strikes, but it managed to take pictures beforehand.

The Soviet Union redirected its Vega 1 and Vega 2 spacecraft toward Halley after both spacecraft had sent probes to Venus’ surface. While the spacecraft passed several thousand miles away from Halley in March 1986, they were still able to take pictures and perform other measurements of the comet’s environment.

These two Japan Aerospace Exploration Agency (JAXA) missions are both asteroid sample-return efforts, like OSIRIS-REx.

Hayabusa launched in May 2003 and arrived at asteroid Itokawa in September 2005. It spent a couple of months at the asteroid studying its composition, then did a touch-and-go operation in November of that year to pick up some grains for analysis. (It also sent a small lander to the surface, MINERVA, which failed.) The Itokawa samples were returned to Earth in June 2010.

Hayabusa2 launched in December 2014 and is currently en route to the asteroid Ryugu. The spacecraft is expected to arrive in July 2018 for a 1.5-year mission, during which it will deploy several landers to the space rock’s surface. After picking up an asteroid sample itself, Hayabusa2 is expected to return to Earth in December 2020.

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ArticleAsteroid Day Partners

The man behind Asteroid Day Italy


This is an op-ed piece by Asteroid Day Italy Coordinator, astrophysicist and founder of the Virtual Telescope (an official partner) Dr. Gianluca Masi.

My interest in asteroids dates back to 1997. Late that year I started observing them with my own telescope from Ceccano, my hometown in Central Italy. It was love at first sight. Those small dots of light, slowly moving across the sky, captured my imagination to the point they became one of the topics of my astronomical activities. In the following years I discovered a few dozens of them, making my adventure into this field even more exciting. One is also named “Masi”, after me.

At that time I was a student in astrophysics, so my interest in minor planets contaminated also my professional path. I ended up discussing a thesis on a very special class of near-Earth asteroids, the so-called inner-Earth ones, moving inside the orbit of our planet, closer than us to the sun. Later, I earned a PhD in astronomy with a thesis investigating NEOs by photometry, studying their rotational properties.

But research is only part of my scientific job. I spend a lot of my time doing science communication and public outreach in astronomy and I’ve found, over the years, that asteroids are a great topic of interest for the general public. Of course, also for the potential risk of collision they pose to our planet.

Since I started the Virtual Telescope Project (to learn more about this facility visit: and its many educational activities, I reserved plenty of attention to near-Earth asteroids, showing the most amazing close encounters with the Earth online, in real time (including the epic case of 2012 DA14), helping the community worldwide to discover what they are and what we can really say about them and their potential impact risk.

This is why I welcomed with plenty of excitement the introduction of Asteroid Day in 2015. I joined it, offering an online show through the Virtual Telescope’s platform. I was happy to learn that Asteroid Day was going to be an annual event and for the 2016 edition I contacted Grig Richters (co-founder of Asteroid Day) offering my help and skills to organise and coordinate Asteroid Day in Italy. Based on my past experience, I was convinced that having a coordinator in a given country, with important, reliable connections within the national astronomical community and the media could be a winning factor to support the goals of Asteroid Day at its best. The response from Grig was very enthusiastic and I started working intensively on this project: Asteroid Day Italia.

I contacted several amateur clubs and media to create a coordinated network. The feedback was amazing and a dozen of clubs enthusiastically joined this pioneering effort, serving as a test for the future of Asteroid Day. The Virtual Telescope offered a specific live feed for Asteroid Day Italia, while the involved clubs organised their own events and the final return was rewarding: tens of thousand of people joined either the online or local Asteroid Day Italia events and without this coordinated work they would have entirely missed the international celebration, according to what some of them told me. That is, they learned about Asteroid Day via its Italian promoter. Asteroid Day Italia was mentioned on all the most important media of my Country. After such a great experience, we are looking forward to the next 2017 edition.

Coordinating Asteroid Day in Italy was a privilege for me (being a fan of Asteroid Day since the very beginning) and a truly rewarding experience. I dedicated plenty of time to this effort, as I believe a lot in it. I think this was easy to perceive, contaminating all the involved partners, bringing their own enthusiasm into this. It was some kind of back-and-forth flux of ideas, energy and excitement. Not an easy task, but I’m so happy for the huge return.

I think, after being the first to test this in Italy in close connection with the Asteroid Day Global team, that having national, motivated coordinators would help a lot to spread Asteroid Day goals and support its mission worldwide. Having individuals knowing their own countries, media and communities will make it possible to better fit each special situation with the maximum return.

To succeed as such a coordinator, you must be truly motivated and “contagious” in your enthusiasm. Of course, you must know your national astronomical community and have good connections with the media and constant feedback with the international team. It is a lot of work, but this is also lot of fun. Engaging clubs will enrich further the experience; you must keep their interest alive, also opening your mind to proposals from them: after all, you are organising all this together.

Working on something you feel close to your vision, making possible to it to reach more and more people in your own community can be very, very exciting. It was for me for sure and I wanted to share my experience with you.

I wish to thank Grig for supporting my ideas and my work in Italy for Asteroid Day.

That said, I’m looking forward to Asteroid Day 2017, and you?

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