Back in August I wrote about a proposal from the Johns Hopkins Applied Physics Laboratory (APL) to fly a robotic helicopter to Saturn’s moon Titan.
Called “Dragonfly”, the mission would use a nuclear-powered dual-quadcopter, an evolution of drone technology, carrying a suite of science instruments to study the moon. Capable of vertical take-off and landing (VTOL) operations, the vehicle would be able to carry out a wide range of research encompassing Titan’s atmosphere, surface, sub-surface and methane lakes to see what kind of chemistry is taking place within them.
The proposal was one of several put forward for consideration by NASA as a part of the agency’s New Horizons programme for planetary exploration in the 2020s. In late December 2017, NASA announced it was one of two finalist proposals which will now receive funding through until the 2018 for proof-of-concept work.
Titan has diverse, carbon-rich chemistry on a surface dominated by water ice, as well as an interior ocean. It is one of a number of “ocean worlds” in our solar system that hold the ingredients for life, and the rich organic material that covers the moon is undergoing chemical processes that might be similar to those on early Earth. Dragonfly would take advantage of Titan’s dense, flight-enabling atmosphere to visit multiple sites by landing on safe terrain, and then carefully navigate to more challenging landscapes.
At 450 kg, Dragonfly is no lightweight, and a fair amount of the mass would be taken up by its nuclear power unit. However, the vehicle will carry a science package comprising some, or all, of the following:
- A mass spectrometer for analysing the composition of Titan’s atmosphere and surface material.
- A gamma ray spectrometer of analysing the shallow sub-surface.
- A seismometer for measuring deep subsurface activity.
- A meteorology station for measuring atmospheric conditions such as wind, pressure and temperature.
- An imaging system for characterising the geologic and physical nature of Titan’s surface and identifying landing sites.
Commenting on the NASA decision to provide further funding for the project, APL Director Ralph Semmel said:
This brings us one step closer to launching a bold and very exciting space exploration mission to Titan. We are grateful for the opportunity to further develop our New Frontiers proposals and excited about the impact these NASA missions will have for the world.
The second proposal to receive funding through until the end of 2018 is the Comet Astrobiology Exploration Sample Return (CAESAR) mission proposed by Cornell University, Ithaca, New York and NASA’s Goddard Space Flight Centre.
This mission seeks to return a sample from 67P/Churyumov-Gerasimenko, a comet that was successfully explored by the European Space Agency’s Rosetta spacecraft, to determine its origin and history. This project is being led by Steve Squyres of Cornell University, who was the principal investigator for NASA’s Mars Exploration Rover missions featuring Opportunity and Spirit.
If approved by NASA, CAESAR would launch in 2024/25, collect at least 100 g (3.5 oz) of regolith from the comet, separating the volatiles from the solid substances. The spacecraft would then head back to Earth and drop off the sample in a capsule, which would re-enter Earth’s atmosphere and parachute down to the surface in 2038. 67P/C-G was selected because it has been extensively imaged and mapped by the Rosetta mission, thus enabling engineers to design a vehicle better able to meet the conditions around the comet as it swings around the Sun.
New Frontiers is a series of planetary science missions with a cap of approximately US $850 million apiece. They include the Juno mission to Jupiter, the Osiris-REx asteroid sample-return missions, and the New Horizons mission to Pluto, also built and operated by APL. Under the terms of NASA funding, both of the 2017 finalists will receive US $4 million each in 2018, and a final decision on which will be funded through to completion will be made in 2019.
WFIRST: Hubble’s New Cousin
While attention is on the next space telescope due for launch – the ambitious James Webb Space Telescope (JWST), which will be departing Earth in 2019 – NASA and the international community is already turning its attention to the telescope that will come after JWST, with a launch due in the mid-2020s.
Billed as a cousin to the Hubble Space Telescope, and something of a descendent of that observatory, the Wide Field Infra-Red Survey Telescope (WFIRST) will use a very similar telescope system as Hubble, with a 2.4m diameter primary mirror, but with a shorter focal length. This, coupled with no fewer than 18 sensors built into the telescope’s camera (Hubble only has a single sensor), means that WFIRST will be able to image the sky with the same sensitivity as Hubble with its 300-mexapixel camera – but over an area 100 times larger than Hubble can image. To put this in perspective: where Hubble can produce a poster for your living room wall, an image from WFIRST can decorate the entire side of your house.
This wide field of view will allow WFIRST to generate never-before-seen big pictures of the universe, allowing astronomers explore some of the greatest mysteries of the cosmos, including why the expansion of the universe seems to be accelerating. One possible explanation for this speed-up is dark energy, an unexplained pressure that currently makes up 68% of the total content of the cosmos and may have been changing over the history of the universe. Another possibility is that this apparent cosmic acceleration points to the breakdown of Einstein’s general theory of relativity across large swaths of the universe. WFIRST will have the power to test both of these ideas.
To learn more about dark energy, WFIRST will use its powerful 2.4-metre mirror and Wide Field Instrument to do two things: map how matter is structured and distributed throughout the cosmos and measure how the universe has expanded over time. In the process, the mission will study galaxies across cosmic time, from the present back to when the universe was only half a billion years old, or about 4 percent of its current age.
The first part of this work – map how matter is structured and distributed through the cosmos – will involve multiple observational strategies, such as surveying supernovae. It was by measuring the brightness and distances of supernovae that provided the first evidence for the presence of dark energy; WFIRST will extend these studies to greater distances to measure how dark energy’s influence increased over time.
In addition, WFIRST will measure precise distances to galaxy clusters by measuring their red shift – the farther away a galaxy is, the redder its light seems to be. This will allow astronomers to determine how they grew over time, and map the positions of galaxies in 3D, enabling them to calculate how the distribution of galaxies has changed over time. This, in turn, feeds back into the study of dark energy, by allowing scientists to measure how it might be affecting the “spread” of the cosmos.
The Wide Field Instrument will also allow WFIRST to measure the matter in hundreds of millions of distant galaxies via weak gravitational lensing. Determined by Einstein in his theory of relativity, massive objects like galaxies curve the space-time around them causing light passing them to also bend, magnifying and distorting the view of more distant galaxies beyond them – gravitational lensing. Measuring this distortion will allow astronomers to gain a broad understanding of how matter is structured throughout the universe, allowing the governing physics of is assembly, as we understand it, to be tested.
Closer to home, so to speak, WFIRST will also be used in the study of exoplanets within our own galaxy, joining the Kepler, JWST and the Transiting Exoplanet Survey Satellite, due for launch in March 2018. This will again involve gravity microlensing, with WFIRST monitoring 100 million stars for hundreds of days. When a star under observation aligns with a more distant star, the lensing effect of its mass magnifies and distorts the light of the background star. As the lensing star drifts along in its orbit around the galaxy and this alignment shifts, so does the apparent brightness of the star, and the pattern of these changes can reveal planets orbiting the lensing star because the planets themselves serve as miniature gravitational lenses.
Such is the sensitivity of WFIRST’s capabilities, it is expected to find around 2,500 exoplanets, many of them rocky worlds smaller than Mars. Thus, WFIRST will play a significant role in completing the survey of planets beyond our own solar system, particularly in the area of identifying rocky planets lying within the habitable zones of their parent stars.
Not only will the telescope be able to locate planets orbiting of stars, it will actually be able to image some of them directly. A coronagraph instrument will allow WFIRST to block out the light of a star, allowing the much fainter planets to be viewed. The instrument will be the most advanced coronagraph flown in space, 1,000 times more capable than any previously flown. Even so, it is only a first generation unit, and will only be able to image gas giant planets roughly Jupiter’s size and orbiting mature Sun-like stars. However, it will pave the way for instruments capable of imaging Earth-sized planets around nearby stars in the future; in the meantime, the instrument will allow the atmospheric properties of relatively nearby gas giants.
By pioneering an array of innovative technologies, WFIRST will serve as a multi-purpose mission, furnishing a big picture of the universe and helping us answer some of the most profound questions in astrophysics, such as how the universe evolved into what we see today, its ultimate fate and – potentially – whether we are alone.
SpaceX Preps Car for Falcon Heavy Launch
SpaceX remains on course for the inaugural flight of the Falcon Heavy booster – billed as the world’s most powerful modern rocket – in January 2018.
Comprising three Falcon 9 first stages strapped side-by-side, and with a payload bearing upper stage on the middle of the three rockets, Falcon Heavy will be capable of lifting up to 54 tonnes to low Earth orbit – and sending around 10 tonnes of payload to Mars. The first flight for the rocket will take place from Kennedy Space Centre’s historic Pad 39A, which SpaceX leased from the US space agency specifically for Falcon 9 and Falcon Heavy launches, and which entered service as a launch platform for the company in February 2017.
The inaugural launch for the new rocket will feature an unusual payload: Musk’s own midnight cherry Tesla roadster – which will, he states, be blasting David Bowie’s Space Oddity on its stereo speaker as it is lifted into space. SpaceX recently released pictures of the car, mounted on a payload adaptor, being amounted within the payload fairings of the Falcon Heavy’s upper stage.
As well as marking the first launch of the new rocket and the first launch of a road car towards Mars, the maiden flight of the system will also be the first time SpaceX will attempt to recover multiple Falcon 9 first stages at one go. Two of the stages will be commanded to perform boost back manoeuvres and attempt safe landings at the SpaceX facilities at Cape Canaveral Air Force Station just south of Kennedy Space Centre. The third will be instructed to land at sea on one of the company’s autonomous drone ships.
As reusability is key to SpaceX’s hopes of reducing launch costs, such multiple recoveries are essential to Falcon Heavy launches for as long as the company intends to operate the launch vehicle. However, Musk and SpaceX have dialled back on the idea of this first flight of the system going smoothly, noting that there is a good chance both vehicle and payload might be lost. Given the Falcon Heavy is a hugely complex system – three rockets all working in concert, twenty-seven main engines, three cores to fly back to a secure landing, there is a lot that could potentially go wrong with a maiden flight intended to gather critical flight data to ensure the success of future Falcon Heavy launches.
Just how long an operational life the Falcon Heavy will have is unclear. Musk has ambitious plans for his Interplanetary Transport System of giant booster rocket and crew / cargo carrying upper stage, and he has hinted that once that system enters operations, both the Falcon 9 and Falcon Heavy could be discontinued in favour of a set of launchers based on the ITS concept. However, this likely wouldn’t happen until the mid-2020s; in the meantime, both Falcon 9 and Falcon Heavy have an ambitious schedule of launches mounting up – including, for Falcon Heavy, flying two space tourists around the Moon and back in its first crew-rated flight, which SpaceX hopes to complete towards the end of 2018, if it gains FAA approval.