Three International Space Station (ISS) crew members safely returned to Earth tonight (Eastern Daylight Time).  They and their Soyuz TMA-20M spacecraft landed in Kazakhstan at approximately 9:14 pm EDT (7:14 am Wednesday local time at the landing site) after 172 days in space.

The three crew members are NASA’s Jeff Williams and Roscosmos’s Oleg Skripochka and Aleksey Ovchinin.  They launched to the ISS on March 19, 2016. 

Williams now holds the U.S. record for total time in space — 534 days over four flights.   Scott Kelly, who returned to Earth earlier this year after spending 340 days on ISS, still holds the U.S. record for continuous time in space.  One of the research goals of the ISS is to study how humans react to long durations in weightlessness in preparation for longer trips to destinations like Mars.

NASA astronaut Jeff Williams (left) minutes after landing in the Soyuz TMA-20M spacecraft in Kazakhstan on September 6, 2016 EDT (September 7 local time at the landing site).  Roscosmos cosmonaut Aleksey Ovchinin is on the right.  Screengrab from NASA TV

Three other crew members remain aboard the ISS:  NASA’s Kate Rubins, JAXA’s Takuya Onishi, and Roscosmos’s Anatoly Ivanishin.  The ISS crew complement will return to its usual six later this month after the September 23 EDT launch of Soyuz MS-02.   Aboard will be NASA’s Shane Kimbrough and two Roscosmos cosmonauts – Andrey Borisenko and Sergey Ryzhikov.

The ISS has been permanently occupied by two-to-six person crews since the end of 2000.  The crews rotate on roughly 4-6 month schedules, although two crew members remained aboard for 340 days — NASA’s Scott Kelly and Roscosmos’s Mikhael Kornienko.  The ISS is a partnership among the United States, Russia, Japan, Canada, and 11 members of the European Space Agency.

Soyuz TMA-20M is the final flight of this version of the Soyuz spacecraft, which made its debut in 1967, but has been upgraded several times.  The most recent upgrade, the Soyuz MS series, had its first flight in July, taking Rubins, Onishi and Ivanishin to the ISS.

The European Space Agency (ESA) exuberantly announced today that imagery from a camera aboard its Rosetta spacecraft has finally located the Philae lander on the surface of Comet 67P.  After returning data for 57 hours in 2014, contact with Philae was lost.  It briefly resumed transmissions in 2015, but ceased again.  The imagery released today confirms that the problem is Philae’s position, which does not allow its solar panels to charge the battery.  The Rosetta mission will end on September 30, so the discovery came just in the nick of time.

The trials and tribulations of the tiny lander made headlines in November 2014 when it separated from Rosetta and headed down to the surface of the comet, the first time such a feat was attempted.  After initial contact, harpoons intended to secure Philae to the surface failed to fire, however, and it bounced twice more before landing elsewhere.  Philae communicates to Earth via Rosetta, which is in orbit around the comet, and communications were established even though ESA and the German space agency, DLR, which built Philae, did not know precisely where it was.

Philae had enough battery power for one round of experiments and it successfully completed 80 percent of them, but contact then was lost and mission managers assumed that the spacecraft landed in a position where sunlight could not reach its solar panels to charge a secondary battery that is aboard.  They hoped that as the comet neared the Sun, more sunlight would reach the panels.  Indeed, Philae “phoned home” briefly in June and July 2015, only to disappear again.

Rosetta has continued to orbit the comet, whose full designation is 67P/Churyumov-Gerasimenko after the two Ukrainian astronomers who discovered it, on its journey in toward the Sun and out again.  The comet-spacecraft duo came closest to the Sun (perihelion) in August 2015.  This is 67P’s first encounter with the Sun and thus it still contains the primordial material of which it was made 4.5 billion years ago making it of special interest to scientists.  

The comet and spacecraft are now on their way back to the outer edges of the solar system.  On October 1, they will move behind the Sun relative to Earth, preventing communications.  Coupled with other technical factors affecting the longevity of the spacecraft and its instruments, program managers decided to formally end the mission on September 30 when they will command it to make a controlled impact with the surface for one last set of observations. 

That final descent is still almost a month away, but the images showing Philae were taken by Rosetta’s narrow-angle camera, OSIRIS, when it was just 2.7 kilometers (1.7 miles) above the surface. Cecilia Tubiana of the OSIRIS team was the first to see the images and identify Philae.   ESA has been looking for Philae all this time and narrowed its location down to a few potential sites, but this is the first time its location could be confirmed.  Philae is “wedged into a dark crack,” ESA said, also proving that the problem is lack of sunlight to charge the secondary battery.

Image of Philae on the surface of Comet 67P from camera aboard ESA’s Rosetta orbiter, September 2, 2016.  Photo credit:  ESA

ESA also released a copy of the image with the spacecraft components labeled.

Image of Philae on the surface of Comet 67P with labels added by ESA to identify spacecraft components.  Photo credit: ESA

ESA Rosetta mission manager Patrick Martin said “[w]e were beginning to think that Philae would be lost forever. It is incredible we have captured this at the final hour.”   ESA Rosetta program scientist Matt Taylor added that now scientists have “ground truth” that will allow them to put Philae’s science data into the proper context.

ESA explains that Rosetta and Philae “aim to unlock the mysteries of
the oldest building blocks of our solar system — comets” and hence the
names are connected to the deciphering of hieroglyphics. 

• Rosetta is named after the Rosetta Stone
  that allowed the deciphering of hieroglyphics and therefore an
  understanding of Egyptian civilization.
• Philae is the name of an island in the Nile river where an obelisk was found with the final clues to enable the decryption.
• Philae was flooded when the Aswan dams
  were built in the 20th century and a complex of Ancient Egyptian
  buildings, including the Temple of Isis, were moved to another island,
  Agilkia,   ESA held a contest to name Philae’s intended landing site on 67P and
  of 8,000 entries, more than 150 suggested Agilkia and that was the
  winner.  Although Philae briefly touched down there, its final landing site is named Abydos after one of the oldest cities in Egypt.
  

Rosetta and Philae were launched on March 2, 2004.  It took 10 years for them to reach their destination — the 4 kilometer (2.5 mile) diameter Comet 67P.  It was 540 million kilometers (335 million miles) from the Sun or 404 million kilometers (251 million miles) from the Earth at that time. As of today, they have traveled 7.9 billion kilometers (4.9 billion miles).  ESA has an interactive “Where is Rosetta” graphic that shows Rosetta’s location at every point along its route.

Rosetta is an ESA mission, but NASA provided three of its instruments and part of the electronics for a fourth.

The National Academies of Sciences, Engineering and Medicine (the Academies) released its mid-term review of the 2010 Decadal Survey for astronomy and astrophysics today. Among its many findings and recommendations, the study warns that recent changes to the design of the WFIRST space telescope, especially the addition of a coronagraph, pose cost risks that could threaten the balanced NASA astrophysics program recommended by the 2010 Survey.  It recommends that NASA perform an independent review before proceeding into the next phase of WFIRST development to determine whether the higher costs are worth the increased scientific capability and, if not, to descope the project to ensure the balanced program is not compromised.

Decadal Surveys and Mid-Term Reviews.

The Academies conduct Decadal Surveys approximately every 10 years (a decade) to identify and prioritize the most important scientific questions facing each of NASA’s space and earth science disciplines and recommend space missions to answer those questions.  The series of Decadal Surveys for astronomy and astrophysics is the oldest, dating back to 1964, and includes programs not only at NASA, but the National Science Foundation (which oversees ground-based astronomy) and, more recently, the Department of Energy (high energy physics).  The other NASA-related Decadal Surveys are in earth science and applications from space, planetary science, solar and space physics (heliophysics), and biological and physical sciences in space.

The agencies and Congress rely heavily on the Decadal Surveys to determine funding priorities and endeavor to follow their recommendations, although budget constraints often intervene.   The agencies tell the Decadal Survey committees at the beginning of their work how much money is expected to be available in the upcoming decade to fund new projects, but those assumptions may change during the course of the 2-year studies, never mind in the decade thereafter, and cost overruns in existing programs may reduce funding availability for those planned for the future.

In the 2005 NASA Authorization Act, Congress directed NASA to contract with the Academies for “performance assessments” mid-way through each Decadal Survey period.  The most recent Survey for astronomy and astrophysics, New Worlds New Horizons (NWNH), was completed in 2010 and thus is now undergoing its mid-term review.

The mid-term review committees are not allowed to change the scientific priorities or mission recommendations in the Decadal Surveys, which are hard fought within the relevant scientific community during the course the Survey.  Instead the mid-term reviews offer guidance on implementing the Surveys and on potential activities to prepare for the next Survey in that scientific discipline.

The Mid-Term Review for the 2010 Astronomy and Astrophysics Survey

Today the Academies released New Worlds New Horizons: A Midterm Assessment, the report of the NWNH mid-term review committee, which was chaired by MIT’s Jacqueline Hewitt.

WFIRST and a Balanced NASA Astrophysics Program.   The Hewitt report reiterates one of the key recommendations from NWNH — to maintain a balanced NASA astrophysics program that funds a suite of “large flagship missions, medium-scale Explorer missions and technology development, and smaller suborbital, data analysis, theory, and laboratory astrophysics programs.”  The concern is that large, expensive “flagship” missions like the James Webb Space Telescope (JWST) can overwhelm the other components of the astrophysics program.  Balance is needed to “optimize the scientific return of U.S. investments and to maintain the health of the U.S. astronomical research community.”

The Hewitt committee expressed concern that recent changes to the design of the Wide-Field Infrared Space Telescope (WFIRST), recommended in NWNH as the first priority for a large space-based astrophysics mission to follow JWST, could grow in cost and threaten that balance.  In particular, the addition of a coronagraph already has added $350 million and could increase costs further, it said.  This issue was raised in a 2014 Academies study chaired by California Institute of Technology’s Fiona Harrison that looked specifically at the pros and cons of adding a coronagraph and is restated in today’s report.

The NASA astrophysics community was stung by significant cost overruns on JWST, whose price tag grew from $1 billion to $8 billion (not including operations) and wants to avoid a similar situation with WFIRST.   When NWNH came out, it anticipated work on WFIRST beginning in 2013, with launch in 2020.  The JWST overruns ate WFIRST’s seed corn, however, and today, in 2016, WFIRST is only in the formulation stage.  Launch is not expected until 2025.  It is being designed to study dark energy and dark matter and search for exoplanets.

The WFIRST concept recommended in NWNH was estimated to cost $1.6 billion.  In 2012, however, the design changed dramatically when the National Reconnaissance Office (NRO), which builds the nation’s spy satellites, gave NASA a telescope it no longer needed for a reconnaissance satellite program that was cancelled.  The NRO telescope is 2.4 meters in diameter, compared to 1.5 meters as recommended in NWNH, and has much improved infrared detectors.  The new version is called WFIRST-AFTA (for Astrophysics Focused Telescope Assets).  More recently, a decision was made to add a coronagraph.  Although the changes mean WFIRST will provide much better data, they also pose cost risks.

The Hewitt committee issued two findings praising the increased scientific capabilities, but also restated the concerns in the Harrison report and made a third finding warning that associated cost growth “could distort the NASA program balance.”  It provides a table showing the cost already has grown from NASA’s initial estimate of $1.8 billion (slightly higher than what was estimated by the NWNH committee due to inflation) to $2.8 billion in FY2015 dollars for a 2025 launch.

WFIRST is currently in Phase A (formulation).  Before moving into Phase B (preliminary design and technology completion), the project must pass a Key Decision Point-B (KDP-B) review.   The Hewitt committee recommends that before KDP-B, NASA commission “an independent technical, management, and cost assessment … including a qualitative assessment of the incremental cost of the coronagraph. If the mission cost estimate exceeds the point at which executing the mission would compromise the scientific priorities and the balanced astrophysics program” recommended in the NWNH, “then NASA should descope the mission to restore” those priorities “by reducing mission cost.”

Explorer Program.  A particular concern is NASA’s support for the Explorer program, which “has a distinguished history of high scientific impact through the deployment of relatively low-cost missions that can respond to opportunities on a short timescale.”  NWNH recommended increasing the number of Explorer missions, but NASA has not been able to implement that recommendation.  It currently plans four Explorers, each with an associated “mission of opportunity,” during the decade covered by NWNH.  The Hewitt committee worries that cost growth in NASA’s large astrophysics programs could threaten even that constrained plan and wants NASA to avoid any more cuts.

Gravitational Waves and X-Ray Astronomy – LISA and IXO. The Hewitt committee also addressed other missions that were considered by NWNH, but were ranked lower in priority, including the Laser Interferometer Space Antenna (LISA) to study gravitational waves and an International X-Ray Observatory (IXO).  NWNH envisioned pursuing both in cooperation with the European Space Agency (ESA).

Gravitational waves were recently detected using the ground-based Laser Interferometer Gravitational-Wave Observatory (LIGO), which the Hewitt committee said buttressed the case for a space-based observatory that can “explore the source-rich millihertz band that is inaccessible from the ground….”   It explained that NWNH expected the space-based LISA to be built through an equal NASA-ESA partnership, beginning with ESA launching a technology demonstration mission, LISA Pathfinder.  ESA launched it last year and the mission is proceeding well.  NASA, however, faced with the JWST cost overruns and the third-level ranking for LISA in NWNH, terminated its own technology development efforts.  ESA is now planning a mission, eLISA (e is for “evolved”), with only minor NASA involvement.  ESA describes it as a joint effort of eight European countries “supported by our colleagues in the US.”

The Hewitt committee noted that NWNH called for a mid-decade assessment of whether to proceed with LISA based on the LISA Pathfinder results and recommends that NASA restore support for gravitational wave research so the U.S. community can “be a strong technical and scientific partner” in eLISA.  It “believes that NASA and ESA together should rethink their strategy” for LISA.

IXO was the fourth priority of NWNH, also envisioned as a NASA-ESA partnership.  NWNH recommended that NASA invest in technology development so that if ESA decided to build an x-ray telescope, NASA would be prepared to contribute to it.  ESA has, indeed, decided to build the Athena x-ray telescope.  Athena’s scope is narrower than IXO, but “enables a compelling subset of the science envisioned for IXO…” according to today’s report.  The Hewitt committee recommends that NASA proceed with its current plan to participate in Athena “with primary contributions directed toward enhancing the scientific capabilities of the mission.”

Dark Energy and ESA’s Euclid.  The Hewitt committee also weighed in on NASA’s participation in ESA’s Euclid mission to understand dark energy.  U.S. plans for a spacecraft to study dark energy went through substantial turmoil just prior to and during the NWNH study.   Eventually, dark energy was included as one of the objectives of WFIRST and NASA also decided, with advice from an Academies committee in 2014, to contribute $20 million of hardware (infrared detectors) to ESA’s Euclid dark energy mission.  The 2014 Academies committee, chaired by Princeton’s David Spergel (who now also is chair of the Academies’ Space Studies Board), also said that if the amount for hardware was to exceed $30 million it should be subject to an independent community review.  The Spergel report also acknowledged that about $20 million ($2 million per year for 10 years) was needed to support U.S. scientists involved in the mission, yielding a total of $50 million for NASA support of Euclid. 

That cost now has risen to $150-200 million according to the Hewitt committee and while most of the funds will be used to support U.S. science teams and archive activities, it nevertheless is well in excess of what the Spergel committee had in mind.  Thus, it recommends that NASA treat any support of Euclid beyond the existing commitments to ESA as lower priority than support of the Explorer program, gravitational wave technology development, or x-ray technology development.

NASA’s Response 

In an emailed statement to SpacePolicyOnline.com today, NASA said it appreciates the efforts of the Hewitt committee and its recognition of the progress NASA has made in meeting what was recommended in NWNH, but will wait to review the new recommendations before making any decisions about the future course of the programs.

“NASA appreciates the hard work that the Mid Term Review Committee did to produce this report. We are pleased that the Committee recognizes the progress that NASA has made in advancing the priorities of the Decadal Survey in a fiscally constrained environment.  The Committee appropriately recognized that NASA has succeeded in maintaining a balanced program, while making substantial progress toward scientific investigations of all scales and over a broad range of astrophysics. The Committee has made a number of thoughtful recommendations, and NASA will review them before making any decisions about changing the planned program.”