With an International Asteroid Warning Network (IAWN) and a Space Missions Planning Advisory Group (SMPAG) now organized, the Working Group on Near-Earth Objects (NEOs) and its Action Team on NEOs (Action Team-14, or AT-14) has deemed its work completed.
AT-14 was established by the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) in 2001. In a report on its fifty second session February 2-13 in Vienna, the COPUOS Scientific and Technical Subcommittee (STSC) says AT-14 is now dissolved. IAWN and SMPAG – a group established to work on plans for asteroid impact mitigation (a.k.a. planetary defense) missions – will now report directly to the STSC. Both groups were formed under the auspices of the U.N. but operate independently of it. AT-14 recommended that both groups seek permanent observer status with COPUOS.
(As a consultant to NASA’s NEO Observations Program, I have been involved in some IAWN activities.)
In a resolution adopted December 5, the U.N. General Assembly noted “the importance of information-sharing in discovering, monitoring and physically characterizing potentially hazardous near-Earth objects to ensure that all countries, in particular developing countries with limited capacity in predicting and mitigating a near-Earth object impact, are aware of potential threats, emphasizes the need for capacity-building for effective emergency response and disaster management in the event of a near-Earth object impact, and recalls in that regard the recommendations for an international response to the near-Earth object impact threat, endorsed by the Scientific and Technical Subcommittee at its fiftieth session and by the Committee at its fifty-sixth session. The General Assembly also “note[d] with satisfaction that progress on establishing an international asteroid warning network and a space mission planning advisory group to implement the recommendations for an international response to the near-Earth object impact threat would be reported to the Subcommittee at its fifty-second session.”
Meanwhile, following its 12th meeting last month, NASA’s Small Bodies Assessment Group (SBAG) stressed – as it did in findings from its 11th meeting last summer – the need for a dedicated space-based NEO survey. “A space-based near-Earth object (NEO) survey telescope would be a foundational asset that would most efficiently achieve the goals of NASA’s Asteroid Initiative in the shortest amount of time. Construction and implementation of such an asset should be supported by all three of NASA’s major space exploration directorates and not just by the limited resources of the Near-Earth Object Observations (NEOO) program within the Science Mission Directorate (SMD). Cross directorate support for a space-based asteroid survey is fully consistent with the Asteroid Initiative already established as an agency-wide goal.” SBAG also reiterated concerns “about the limited benefits of ARM [NASA’s Asteroid Retrieval Mission] for advancing asteroid science or furthering planetary defense strategies, and that limits in the current knowledge of near-Earth asteroids contribute to schedule and cost risks.”
NASA had originally planned to announce its selection of option A or option B for the ARM in December. That decision was put on hold, and no one seems to know when it will be announced.
In an op-ed posted by Aviation Week today, space policy analyst Marcia Smith raises some questions about the ARM mission. “ARM is two good ideas kluged together into one bewildering idea that NASA itself seems unable to explain effectively.” Smith notes that one aspect of the ARM “that piques a lot of interest is the idea that ARM will lead to technologies to defend Earth from threatening asteroids (“planetary defense”). Although that gets a lot of attention, it actually is not an expected outcome of ARM…. NASA needs an Asteroid Deflection Technology Development program, not ARM.”
On a more upbeat note, SBAG notes that this year will be “a banner year for small bodies science,” with missions to explore the dwarf planets Ceres and Pluto and comet Churyumov-Gerasimenko. “The attention [these missions] will attract gives the small body science community a spectacular opportunity to communicate the value of our work,” SBAG notes in findings from its January meeting. “[W]e must all make an extra effort this year to engage with the public over these exciting missions.”
(Science magazine (December 14) declared the European Space Agency’s Rosetta mission landing of a probe on comet Churyumov-Gerasimenko the top science “breakthrough” or 2014.)
While the NEO community is essentially in agreement that a dedicated space-based NEO survey telescope would be a valuable asset, no one yet has the funding to develop such a mission. The B612 Foundation is attempting to raise private funding for such a telescope – its project is called Sentinel – but apparently has been unsuccessful thus far. The last Sentinel project status update posted on B612’s web site is dated September 2013. The Jet Propulsion Laboratory’s proposal to build a Discovery-class NEO survey telescope called NEOCAM (NEO Camera) was not selected for funding the first time around. JPL resubmitted the NEOCAM proposal in response to NASA’s next Discovery call for proposals, and it’s currently under review. (Discovery missions must cost less than $425 million and take no more than three years to develop from mission start to launch.) In April 2013, an infrared sensor being developed for the NEOCAM mission passed a critical design test.
In a paper to be published in the Astronomical Journal (Mainzer et al. 2015 in press), NEOCAM principal investigator Amy Mainzer and her team report on simulations they conducted “to predict the performance of a new space-based telescopic survey operating at thermal infrared wavelengths that seeks to discover and characterize a large fraction of the potentially hazardous near-Earth asteroid (NEA) population” – that is, NEOCAM. The team considered two potential architectures for the survey: a telescope located at the Earth-Sun L1 Lagrange point, and one in a Venus-trailing orbit. Their results “indicate that the Earth-Sun L1 and Venus-trailing surveys achieve similar levels of integral completeness for potentially hazardous asteroids larger than 140 m; placing the telescope in an interior orbit does not yield an improvement in discovery rates.” They report that the L1 survey “slightly outperforms the Venus-trailing survey for PHAs in this [larger than 140 meters] size range.”
“Unlike ground-based surveys, space telescopes at either L1 or Venus-trailing orbits can spend much of their time surveying the region of sky that is in the daytime sky for ground-based observers. Therefore, the ability to perform ‘self follow up’ is essential because ground-based observers cannot be relied upon regularly for the short-term follow up required to determine orbits securely,” they note.
Mainzer et al claim their results “demonstrate that the cost, complexity, and risk associated with sending a survey telescope to a Venus-trailing orbit is unwarranted. While neither survey [architecture] is capable of fulfilling the 2005 Congressional mandate to NASA to find 90% of all near-Earth objects larger than 140 m in diameter by 2020, an advanced space-based survey can make significant progress quickly.”
Finally, as spring approaches (what a nice thought!), we’ll be hearing more about International Asteroid Awareness Day – a.k.a. Asteroid Day. (You can read more about Asteroid Day in one of my earlier posts.) Many of my colleagues in the NEO community are skeptical of one particular “call to action” in a declaration for which Asteroid Day sponsors are seeking signatures – “a rapid hundred-fold (100x) acceleration of the discovery and tracking of Near-Earth Asteroids to 100,000 per year within the next ten years.” They say it’s a nice idea, but likely impossible to achieve for a number of reasons.