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Rosetta: Building Momentum for Deep Space?

Even though its arrival on the surface of comet 67P/Churyumov-Gerasimenko did not go as planned, the accomplishment of the Rosetta probe is immense. We have a probe on the surface that was able to collect 57 hours worth of data before going into hibernation, and a mother ship that will stay with the comet as it moves ever closer to the Sun (the comet’s closest approach will be on August 13 of next year).

What a shame the lander’s ‘docking’ system, involving reverse thrusters and harpoons to fasten it to the surface, malfunctioned, leaving it to bounce twice before it landed with solar panels largely shaded. But we do know that the Philae lander was able to detect organic molecules on the cometary surface, with analysis of the spectra and identification of the molecules said to be continuing. The comet appears to be composed of water ice covered in a thin layer of dust. There is some possibility the lander will revive as the comet moves closer to the Sun, according to Stephan Ulamec (DLR German Aerospace Center), the mission’s Philae Lander Manager, and we can look forward to reams of data from the still functioning Rosetta.

What an audacious and inspiring mission this first soft landing on a comet has been. Congratulations to all involved at the European Space Agency as we look forward to continuing data return as late as December 2015, four months after the comet’s closest approach to the Sun.


Image: The travels of the Philae lander as it rebounds from its touchdown on Comet 67P/Churyumov Gerasimenko. Credit: ESA/Rosetta/Philae/ROLIS/DLR.

A Wave of Discoveries Pending

Rosetta used gravitational assists around both Earth and Mars to make its way to the target, hibernating for two and a half years to conserve power during the long journey. Now we wait for the wake-up call to another distant probe, New Horizons, as it comes out of hibernation for the last time on December 6. Since its January, 2006 launch, the Pluto-bound spacecraft has spent 1,873 days in hibernation, fully two-thirds of its flight time, in eighteen hibernation periods ranging from 36 days to 202 days, a way to reduce wear on the spacecraft’s electronics and to free up an overloaded Deep Space Network for other missions.

When New Horizons transmits a confirmation that it is again in active mode, the signal will take four hours and 25 minutes to reach controllers on Earth, at a time when the spacecraft will be more than 2.9 billion miles from the Earth, and less than twice the Earth-Sun distance from Pluto/Charon. According to the latest report from the New Horizons team, direct observations of the target begin on January 15, with closest approach on July 14.

Nor is exploration slowing down in the asteroid belt, with the Dawn mission on its way to Ceres. Arrival is scheduled for March of 2015. Eleven scientific papers were published last week in the journal Icarus, including a series of high-resolution geological maps of Vesta, which the spacecraft visited between July of 2011 and September of 2012.


Image (click to enlarge): This high-resolution geological map of Vesta is derived from Dawn spacecraft data. Brown colors represent the oldest, most heavily cratered surface. Purple colors in the north and light blue represent terrains modified by the Veneneia and Rheasilvia impacts, respectively. Light purples and dark blue colors below the equator represent the interior of the Rheasilvia and Veneneia basins. Greens and yellows represent relatively young landslides or other downhill movement and crater impact materials, respectively. This map unifies 15 individual quadrangle maps published this week in a special issue of Icarus. Credit: NASA/JPL.

Geological mapping develops the history of the surface from analysis of factors like topography, color and brightness, a process that took two and a half years to complete. We learn that several large impacts, particularly the Veneneia and Rheasilvia impacts in Vesta’s early history and the much later Marcia impact, have been transformative in the development of the small world. Panchromatic images and seven bands of color-filtered images from the spacecraft’s framing camera, provided by the Max Planck Society and the German Aerospace Center, helped to create topographic models of the surface that could be used to interpret Vesta’s geology. Crater statistics fill out the timescale as scientists date the surface.

With a comet under active investigation, an asteroid thoroughly mapped, a spacecraft on its way to the largest object in the asteroid belt, and an outer system encounter coming up for mid-summer of 2015, we’re living in an exciting time for planetary discovery. But we need to keep looking ahead. What follows New Horizons to the edge of the Solar System and beyond? What assets should we be hoping to position around Jupiter’s compelling moons? Is a sample-return mission through the geysers of Enceladus feasible, and what about Titan? Let’s hope Rosetta and upcoming events help us build momentum for following up our current wave of deep space exploration.


Comments on this entry are closed.

  • ljk November 24, 2014, 12:52

    I have been told that the harpoon system on Philae was *not* tested in a vacuum before the Rosetta mission was launched in 2004. The ESA team did not check the system until September of this year! They discovered the harpoons would not work in the vacuum of space, as was sadly demonstrated on November 12.

    I tried to learn more on this surprising information – such as why would such a critical system on Philae not have been tested in a simulated space environment before launch – but nothing has since been forthcoming, no real surprise there. The Planetary Society’s Facebook page had a thread inviting anyone to ask any question about the Rosetta mission. I asked my question about the harpoons and was only told that they would not have worked anyway on the comet’s harder than thought icy crust – which of course circumvented my original question altogether. I asked the question again but I have a feeling that little Philae will awaken from its “nap” before I ever get an answer, at least from those sources.

  • Robert November 24, 2014, 14:55

    Shame is an understatement. The public simply cannot be expected to spend that kind of money on highly questionable technology. Scandal would be a better word.

  • ljk November 24, 2014, 15:10

    Why the Rosetta mission is this generation’s moon landing

    Nov 21, 2014 by Sadie Jones, The Conversation


    Philae Lander, Like Philae Obelisk, Is a Window to the Past

    Ben Altshuler, Oxford University | November 19, 2014 03:00 pm ET


  • James M Essig November 24, 2014, 15:11

    Awesome article Paul! We are definitely coming of age in the Solar System.

    It would be interesting if we could position high specific impulse chemical fuels in depos further out into the solar system as ready to use fuel sources for manned missions and future prospects for interplanetary commerce.

    I suppose reaction mass supplies for VASIMIR engine powered craft would be well to position around the gas giants and even Plutonian orbits.

    Space exploration is becoming much fun again. I am greatly looking forward to the test launch of the CEV this December. The vehicle will experience temperatures as high as 4,000 degrees F on re-entry. Materials science and engineering is as big of a key to the puzzle as anything else.

  • Ashley Baldwin November 24, 2014, 16:33

    Yes, great article on an exciting subject. I believe we will see more deep space missions because of two new developments. The advent of cheap, heavy launchers from commercial companies like SpaceX. The Falcon Heavy is due for its first full tests next year and is the first rocket capable of launching meaningful payloads to Mars , Jupiter and beyond ,direct ,since the Saturn V. It’s maximum cost us circa $130 million too which is a quarter of NASA’s SLS system, also due for testing in the next 18 months and capable of lifting even more . Up to 70 tonnes. Both SLS and Falcon Heavy can launch deep space manned spacecraft too, the Orion spacecraft and V2. Space X are also talking of making an even heavier launch vehicle, the Falcon XX . If they pursue their plans for reusable rockets we will have multiple, cheap long range launch vehicles. No more long sling shot missions.
    The other is the development of the NEXT ion drive, xenon based thruster system which is designed for reliable and gradual acceleration for prolonged periods, making it ideal for deep space missions . Even it is only really a prototype with bigger, more powerful versions hard on its heels . All of this is going to make deep space missions easier, cheaper and quicker. So I do think we will see Jupiter and Saturn moon missions launch in the next decade. The ESA are due to launch JUICE to the icy moons of Jupiter in 2023 and are considering a joint Uranus/Neptune probe , ODINUS, for their next “L” class mission if they can get enough plutonium 238 the the radio isotope thermoelectric generators, the decay of which produces the electrical power necessary to operate a spacecraft at long distances from the sun. NASA are planning a Europa clipper orbiter that will also launch next decade. JUICE may even have a lander if the Russians get there act together .( in many ways)

  • Robert November 24, 2014, 16:39


    Yes, it would seem to be better to spend money now developing a truly robust and versatile system to tool around the Solar system first and then do these missions all day long instead of spending multi billions of dollars on each unique and special mission at the very limits of technological possibility. For example, a truly useful and cost effective system would be one in which a probe could be outfitted and sent to such a comet in a period of months, not ten years, and then another if more data was requested.

  • Geoffrey Hillend November 24, 2014, 16:58

    Quote by James M Essig: “I suppose reaction mass supplies for VASIMIR engine powered craft would be well to position around the gas giants and even Plutonian orbits. ” Now you’re talking. VASIMIR powered craft don’t even have to be manned.

  • ljk November 24, 2014, 18:45

    The sound of the first more-or-less soft landing by a probe on a comet:


    Deep Impact technically landed the first human-made object on a comet in 2005, if you count an 800-pound copper ball smashing into it at high speed a landing.

  • william November 24, 2014, 19:30

    Materials science and engineering ! That is what I’ve forgotten to ask you about Paul, would you do some investigative reporting on the status of material sciences in the space programs ? For example, I would love to see more detailed discussions on whether or not airlocks both internal and external to a spaceship has been developed so far. In the movies, these hatches always work flawlessly. What is the contrast between the two ?

    Also too, Paul has there been any announcements of video links to the last conference that you attended ?

  • william November 24, 2014, 20:09
  • Paul Gilster November 24, 2014, 21:43

    william writes:

    Also too, Paul has there been any announcements of video links to the last conference that you attended ?

    When I have a link to video, I will be glad to post it. Re materials science, I’ll keep that request in mind as well.

  • Lionel November 25, 2014, 8:06

    Great article Paul, also very interested by the developments Ashley Baldwin wrote about above – when I get a bit of free time will endeavour to read more!

  • ljk November 25, 2014, 10:14

    Philae: The bouncing baby space probe that gave itself another chance

    By Dave Gilbert, CNN

    updated 4:18 PM EST, Mon November 24, 2014

    London (CNN) — It flew for 10 years, crossed millions of miles of space, bounced over the surface of a comet and returned heaps of data … and then quietly faded away.

    The little spacecraft Philae that has captured the imagination of thousands with endearing tweets to the comet-chasing mother ship Rosetta stopped transmitting when its batteries drained.

    “@ESA_Rosetta I’m feeling a bit tired did you get all my data? I might take a nap …” The forlorn message was picked up by followers of @Philae2014 shortly before it fell silent.

    Rosetta and Philae’s love affair

    The Rosetta orbiter mission will continue to track Comet 67P on its journey around the sun in the coming months but after the final transmission from Philae, the lander mission appeared to be over.

    But is it?

    Scientists from the European Space Agency (ESA), which is leading a consortium that includes NASA to find out more about the composition of comets and how they interact with the sun, say there’s still a good chance that Philae will revive.

    A touchdown 10 years in the making Rosetta scientist inspires next generation Sheer breath-taking human ingenuity

    And the malfunction that caused the probe to bounce in the very weak gravity might actually turn out to be a blessing.

    “It’s good luck through bad luck,” said lander system engineer Laurence O’Rourke

    Full article here:


  • Wojciech J November 25, 2014, 19:40

    I personally consider Ceres one of the most interesting targets for human colonization(low gravity, and a lot of water and other resources, combine this with tethered orbital stations for habitation and farming and you have great potential), so I am fascinated by this mission and what we will see. Ceres doesn’t seem like a typical case among the objects we observed so far and it will amazing to discover what secrets it will display.
    Likewise to see the surface of Pluto which inspired us for such a long time being one of the farthest planetary objects known to us in Solar System(up to recent decade of course) is breathtaking. Can’t wait!

  • Erik Landahl November 25, 2014, 23:31

    My desire to see the world engage in a massive space mission that will inspire my children and the generation after them is intense. I want my children to experience the hope and optimism about human potential and humanity’s future that I felt during Apollo.

    However, the the premise that Rosetta-Philae is this generation’s Apollo 11 – as written in The Conversation article (via Phys.org) posted by ljk – my gosh is this an absurd comparison!

    If the Eagle lander had truly foreshadowed Philae, it would have bounced 3 times and landed on its side in a boulder field. The world would have watched, horrified, as the Neil and Buzz slowly ran out of power and oxygen and eventually died on the lunar surface. We would, however, be eternally grateful for the information they managed to transmit to Earth during their brief life on the Moon. Armstrong and Aldrin’s mummified bodies would lie there today, an unintended monument to bravery and exploration.

    Also, if the Apollo-Philae comparison is valid, go across the street and ask your neighbor “Hey, where were you when Philae landed?” Ask the coffee shop barista, “What did you feel when the Philae harpoons didn’t stick?” Each will likely look at you with bemused confusion and ask you what the heck Philae is.

    I admire the Rosetta-Philae mission and I watched it closely and I loved the excitement of the landing. However, it is no Apollo 11. It is not even an Apollo 13. It will take a manned return to the Moon to once again ignite the passion and wonder felt from 1961-1972.

  • ljk November 26, 2014, 12:03

    With no serious plans to send humans back to the Moon or on to Mars (oh sure, NASA keeps talking about doing in sometime in the 2030s, but they are the same ones who said it would happen in the 1980s back in the 1960s), and the anthropomorphizing of little Philae, even though it looks like a box on metal legs, I guess we have to take what we can get for now when it comes to space exploration.

    Certainly exploring a comet directly is very important and historic, but the general public is generally distracted and focused on the drama they create on this planet, so I agree that calling it our Apollo 11 moment is a bit much. If three working rovers on Mars could not muster it, a short-lived probe on a comet with a name most people cannot remember or recognize will eventually not cut it, either.

    But it should.

  • Wojciech J November 26, 2014, 18:40

    Erik Landahl:
    “It will take a manned return to the Moon to once again ignite the passion and wonder felt from 1961-1972.”
    Moon landing has been done, and while Moon is fascinating place for space enthusiasts and scientists, it is relatively boring to the public. The only thing that could be somewhat equal to Moon landing would be a manned Mars mission. Also getting a visible image of exo-Earth with biosphere signs visible(green cover of continents) or discovery of life on other planet/moon in Solar System would score higher than Moon Landing in history and inspire whole generations.

  • Dmitri November 29, 2014, 10:19

    I don’t get the negativity towards Philae landing or even remotely call it failure. Sounds like Americanism in work. As the MUPUS instrument showed the surface where Philae eventually landed was hard. Very hard. So hard that Philae’s mode 4, “super crazy” where the lead designer warned never go to or with extreme caution, broke down physically meaning it conclusively proved the material is harder than > 2 MPa. The landers harpoons were designed for 8-10MPa hardness. It’s not harpoons to blame but the downward pushing thruster not deploying properly otherwise it would have prevented the bounces. It’s totally unclear nor subject for speculation would have harpoons anchored to the surface. 2 of 3 ice screws on the landing gear did hooked into soil at the very final Philae place. As the result show so far the 67P surface has 10-20 cm dust layer on top of very hard comet layer. It’s unclear what it is, speculation it is porous sintered ice, having centuries or millennia for to reach such strength. Philae’s mission is to sort out is this local phenomenon (the final resting place) or global (over the 67P). For the moment anything other is excluded based on material density readings. Ambient temperature around MUPUS deployment motor was -125C. Terrestrial analogues: Sandstone has about 5-15MPa, Granite 5-20MPa Tensile strenght.

    Philae’s biggest problem is overheating. Currently it sits in natural shade & ESA mission participants telling the cooling problem has been solved in natural way. On the Algikia the eventual death of lander would have been very quick precisely due to overheating. All 10 instruments worked perfectly, the batter lasted its nominal 64h (Huygens probe lasted only 3h), the lander has been raised 15 cm & the body turned 35-degree so the biggest solar panel could get enough sunlight to recharge. If not earlier then when the next season kicks in (spring 2015) Philae will give sign of life. Considered the peak of energy from the Sun in August there’s even good chance it will survive the ordeal compared to be landed on Agilkia.

    I’m here with the program lead who said:”Don’t stress on what we could have had but what we have delivered. This is absolutely a success in every meaning”.

    If Philae would have had landed on its initial spot there wouldn’t have been such results & probably many findings would have been “within the expected range & theories”.

    It takes 50W alone to warm-up the secondary battery to the state it could start to recharge. Everything takes time. The natural environment on the 67P gently put the Philae into even more favorable place than was anticipated.

  • Alex Tolley December 2, 2014, 13:34


    I don’t get the negativity towards Philae landing or even remotely call it failure. Sounds like Americanism in work.

    Who is calling it a failure? I’ve seen nothing but plaudits for this mission, including the Philae lander. We are all waiting for the science to be published to understand what has been discovered about the comet’s surface conditions.

  • ljk December 11, 2014, 14:13

    Direct exploration versus lots of speculation equals often learning that the Universe does not operate the way humans think it does or want it to.

    Case in point:


    This is why I want us to ramp up SETI and interstellar exploration as opposed to endless debates about real alien life.

  • ljk January 7, 2015, 10:29

    Is this the other reason ESA has been less than forthcoming on certain data from their Rosetta mission?


    As I said earlier in this comment thread, I was told the harpoon system which did not work with Philae had not been tested before the probe launched in 2004 and the ESA team tested it only one month before the landing, where they discovered the system does not work in a vacuum! Do we now have a similar scenario with the drill? What else did not work with Philae and why?