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This chapter provides a substantive introduction to and contextualization of the contents of the volume. In addition to describing the methods used to select contributors, it discusses themes of major importance not only in this book, but also in spaceflight culture more generally. These themes include: (1) the need to understand the global impact of space exploration’s colonialist and imperialist history; (2) the need to understand the economic ideologies that underlie American space advocacy; (3) the need to understand how spaceflight’s history and culture have influenced national and international space legislation; and (4) the need to frame and understand debates about spaceflight objectives as ethical debates. Following this, the chapter provides a short summary of each chapter in the volume.

“Appreciating What’s Beautiful about Space” uses a critical perspective to explore spaceflight culture and the appreciation of space exploration in the United States. It argues that appreciating what’s beautiful about space requires learning about the space environment for what it is in itself, for instance through scientific investigation (but also through literary, artistic, and other creative means provided they are focused on depicting the space environment itself, as opposed to depictions of human activities in space). It argues further that we should use the knowledge and experience gained through studying the space environment to craft our own visions for humanity’s future in space. We should not rest content with underdeveloped plans for space expansion crafted by exorbitantly wealthy and powerful owners of major space firms, especially as their plans have been crafted neither in consultation with, nor to advance the interests of, the overwhelming majority of human beings on Earth.

Rooted in a trans-territorial framework, the present study was designed to provide new evidence regarding the patterns of communication among Hurricane Maria survivors who migrated to the U.S. in the aftermath of the storm.A total of 319 Hurricane Maria survivor adults ages 18 and older were recruited into the Adelante Boricua study between August 2020 and October 2021. Most participants had relocated to the U.S. between 2017 and 2018. We used latent profile analysis and multinomial regression to examine the relationship of technology-based communication with depressive symptoms, well-being, cultural connection, and migration stress.We identified a five-class solution, consisting of (1) moderate communication (32%), (2) disengaged (24%), (3) no social media (18%), (4) daily with family in Puerto Rico (6%), and (5) daily trans-territorial (13%) typologies. Participants in the disengaged class were more likely to report elevated depressive symptoms and limited English proficiency, lower prosocial behaviors, lower levels of religiosity, lower attendance at religious services in the U.S., and less engagement in social activities, compared to participants in the Moderate Communication class.Roughly one in four individuals in our sample reported very limited technology-based communication with friends/family in their sending and new-receiving communities. As technology and smartphones continue to become integrated into 21st-century life, it is vital that researchers explore how the tremendous potential for connectedness relates to trans-territorial crisis migrants' well-being and adaptation.

This chapter argues that the demanding nature of space environments (their hostility to human life; their lack of breathable air and consumable water) create a substantive obligation on the part of any space society to provide its citizens with guaranteed access to life support. Borrowing from Shue’s (1996) defence of subsistence rights, which calls for the protection of basic rights against ‘standard threats’, the chapter argues that space societies will be obliged to protect a right to life support (or to provide ‘life support security’). The ‘standard threats’ to life support security can be diminished significantly by refraining from pursuing space settlement projects that are likely to generate conditions of life support insecurity. It is within our power to determine the material conditions during the founding and early development of space societies. In response to the criticism that providing guaranteed access to life support in space would be hopelessly utopian or idealistic, the chapter argues that there are few known constraints on the developmental pathways of space societies. It is not known, and it cannot be assumed as an uncontroversial truth, that, whenever space societies are founded, it will not be feasible for them to provide guaranteed access to life support. Further, pessimism about human motivation also fails to provide a compelling objection to the requirement of guaranteed access to life support, because human motivation is subject to change on the timescales needed to plan and instigate space settlements.

Observations by Magnetospheric Multiscale have demonstrated that magnetic reconnection occurs at Earth's bow shock, typically at thin current sheets arising from plasma instabilities and turbulence in the shock transition region. Observational surveys of both the shock transition and the magnetosheath downstream suggest that the number of current sheets in these regions may not be strongly dependent on the shock Mach number MA or the angle between the upstream magnetic field and shock normal ( θBn). This result is somewhat surprising given that quasi-parallel and high Mach number shocks tend to have a more disordered and non-stationary structure. In order to investigate how shock reconnection manifests across different parameters, we perform a series of hybrid (fluid electron, kinetic ion) particle-in-cell simulations across a range of Mach numbers and orientations. Given that hybrid simulations cannot resolve electron-scale current sheets and reconnection, these simulations isolate an ion-scale mechanism for shock reconnection driven by an ion–ion beam instability in the foot. We find that this mechanism is strongly constrained to quasi-parallel shocks across all simulated Mach numbers. By quantifying reconnection using the area occupied by plasma on closed magnetic field lines, we find the number of reconnecting structures and closed field area increase with MA and decrease with θBn in the upstream and ramp regions. Downstream of the shock, however, we find a similar result to observational surveys: within the subset of quasi-parallel shocks, the decay rate of the closed field area (and hence thin current sheets) is not strongly dependent on upstream shock parameters.

We present observations that suggest the X-line of guide-field magnetic reconnection is not necessarily orthogonal to the plane in which magnetic reconnection is occurring. The plane of magnetic reconnection is often referred to as the L–N plane, where L is the direction of the reversing and reconnecting magnetic field and N is normal to the current sheet. The X-line is often assumed to be orthogonal to the L–N plane (defined as the M-direction) in the majority of theoretical studies and numerical simulations. The four-satellite Magnetospheric Multiscale (MMS) mission, however, observes a guide-field magnetic reconnection event in Earth’s magnetotail in which the X-line may be oblique to the L–N plane. This finding is somewhat opportune as two of the MMS satellites at the same N location report nearly identical observations with no significant time delays in the electron diffusion region (EDR) even though they have substantial separation in L. A minimum directional derivative analysis suggests that the X-line is between 40° and 60° from M, adding support that the X-line is oblique. Furthermore, the measured ion velocity is inconsistent with the apparent motion of the MMS spacecraft in the L-direction through the EDR, which can be resolved if one assumes a shear in the L–N plane and motion in the M-direction. A nonorthogonal X-line, if somewhat common, would call for revisiting theory and simulations of guide-field magnetic reconnection, reexamination of how the reconnection electric field is supported in the EDR, and reconsidering the large-scale geometry of the X-line.

We investigate the dynamics of Earth's quasi-parallel terrestrial bow shock based on measurements from the Magnetospheric MultiScale (MMS) spacecraft constellation during a period of near-radial interplanetary magnetic conditions, when the interplanetary magnetic field and the solar wind (SW) velocity are nearly anti-parallel. High-speed earthward ion flows with properties that are similar to those of the pristine SW are observed to be embedded within the magnetosheath-like plasma. These flows are accompanied by Interplanetary Magnetic Field (IMF) intensity of less than about 10 nT, compared to nearby magnetosheath intensities of generally greater than 10 nT. The high-speed flow intervals are bounded at their leading and trailing edges by intense fluxes of more energetic ions and large amplitude quasi-sinusoidal magnetic oscillations, similar to ultra-low frequency waves known to steepen and pileup on approach toward Earth to form the quasi-parallel bow shock. The MMS string-of-pearls configuration is aligned with the outbound trajectory and provides inter-spacecraft separations of several hundred km along its near 103length, allowing sequential observation of the plasma and magnetic field signatures during the event by the four spacecraft. The SW-like interval is most distinct at the outer-most MMS-2 and sequentially less distinct at each of the trailing MMS spacecraft. We discuss the interpretation of this event alternatively as MMS having observed a quasi-rigid bow shock contraction/expansion cycle, ripples or undulations propagating on the bow shock surface, or a more spatially local evolution in the context of either a deeply deformed shock surface or a porous shock surface, as in the three-dimensional patchwork concept of the quasi-parallel bow shock, under the extant near-radial IMF condition.

Collisionless shocks are some of the most efficient particle accelerators in heliospheric and astrophysical plasmas. Here we study and quantify ion acceleration at Earth's bow shock with observations from NASA's Magnetospheric Multiscale (MMS) satellites and in a global hybrid-Vlasov simulation. From the MMS observations, we find that quasiparallel shocks are more efficient at accelerating ions. There, up to 15% of the available energy goes into accelerating ions above 10 times their initial energy. Above a shock-normal angle of similar to 50 degrees, essentially no energetic ions are observed downstream of the shock. We find that ion acceleration efficiency is significantly lower when the shock has a low Mach number (M ( A ) < 6) while there is little Mach number dependence for higher values. We also find that ion acceleration is lower on the flanks of the bow shock than at the subsolar point regardless of the Mach number. The observations show that a higher connection time of an upstream field line leads to somewhat higher acceleration efficiency. To complement the observations, we perform a global hybrid-Vlasov simulation with realistic solar-wind parameters with the shape and size of the bow shock. We find that the ion acceleration efficiency in the simulation shows good quantitative agreement with the MMS observations. With the combined approach of direct spacecraft observations, we quantify ion acceleration in a wide range of shock angles and Mach numbers.

Similarities among nutritionally relevant carotenoid profiles in red- and yellow-fleshed papaya (Carica papaya L.) cultivars were revealed using liquid chromatography coupled to mass spectrometry. Differences were observed mainly in lycopene content. Where yellow papayas contain only trace amounts of lycopene, it is the predominant carotenoid in red papayas. Chromoplast morphology and ultrastructure of red- and yellow-fleshed papayas were investigated using light and transmission electron microscopy. Carotenoids in yellow papaya were deposited in tubular plastids, while crystalloid substructures in red papaya chromoplasts were associated with lycopene accumulation. Carotenoid deposition may be relevant to its bioavailability. Therefore, this parameter was compared among papaya, carrot, and tomato using 16 healthy human subjects for a randomized crossover study. Test meals were adjusted in order to deliver equal amounts of β‑carotene and lycopene. Triacylglycerol-rich lipoprotein fractions were analyzed for 9.5 hours after test meal consumption. β‑Carotene of papayas was approximately three times more bioavailable than that of carrots and tomatoes. Moreover, lycopene bioavailability in papayas was approximately 2.6 times higher than that of tomatoes. Bioavailability of β‑cryptoxanthin from papayas was higher when compared with the other papaya carotenoids, β‑carotene and lycopene, respectively 2.9 and 2.3 times higher. Liquid-crystalline deposition of β‑carotene and the storage of lycopene in very small crystalloids in papayas may play an important role in improving the bioavailability of such carotenoids when compared with other deposition forms.

I review Mars science goals, including those associated with the study of Mars’ past and present habitability, as well as those associated with understanding Mars’ atmosphere and climate. I argue t...

In this paper I argue that obligations associated with the scientific exploration and study of the solar system are, over sub-millennial timescales, stronger than obligations associated with the preservation of humanity via space settlement. Thus my objection is not to space settlement as such, but rather, to those claiming an urgent need to instigate space settlement. I also argue that the “disposable planet mentality” objection to space settlement is ill-founded.

This special issue grew out of a series of discussions on the ethics of human colonization in the context of the 2018 SoCIA (Social and Conceptual Issues in Astrobiology) meeting in Reno, NV. These exchanges, both by email prior to the meeting and during the panel discussion there, were so lively and engaging that we wanted to find a way to capture their spirit in print. The Great Colonization Debate is thus an unusual format for an academic piece, reading more like an informal debate where all the contributors have an opportunity to engage one another, interactively exploring the ideas they present in their separate pieces. We hope that it will serve as an interesting and informative introduction to what follows.

We examine a rare and interesting observation of magnetic reconnection embedded in a large-scale region of strong turbulence in which magnetic field annihilation is energizing ions and electrons. The magnetic reconnection event is in Earth’s magnetotail and is associated with enhanced energetic particle fluxes indicating local particle acceleration. Despite substantial electric and magnetic field fluctuations throughout the surrounding, large-scale region, the ongoing magnetic reconnection has many similar properties to laminar, 2D magnetic reconnection including Hall electric fields, Hall magnetic fields, a thin electron current sheet, and ion and electron jets. Notably, the electron jet emerging from the electron diffusion region (EDR) appears to transport sufficient off-diagonal momentum to infer that off-diagonal electron stress can support the reconnection electric field in the EDR even in a turbulent environment. Although the electron jet appears to be briefly (∼1 s) deflected or possibly interrupted by an electromagnetic disturbance, the reconnection appears to otherwise continue for a long period (∼30 minutes) as evidenced by a persistent ion jet. This particular finding implies that the fundamental electron-scale processes inside of the EDR in turbulent magnetic reconnection are not necessarily distinct from those in laminar magnetic reconnection. These observations provide direct confirmation that magnetic reconnection can not only be responsible for but also can continue in regions of large-scale turbulence. Because the electric and magnetic fields of strong turbulence are linked to particle acceleration, it follows that particle acceleration also can continue as a consequence of turbulent magnetic reconnection.

I argue that citizens of future lunar states should enjoy the right to emigrate. The lethality of the space environment may result in lunar settlements pursuing oppressive and illiberal norms, policies, and laws in order to resolve societal problems. A right to emigrate, which for the foreseeable future is tantamount to a right to return to Earth, has individual and societal value. For individuals, the right establishes a legal path for lunar citizens wishing to flee from averse social or political circumstances. For the lunar state, protecting the right to emigrate disincentivizes the pursuit of policies which give rise to desires to flee. After presenting the case for the right to emigrate, I respond to several objections, including an objection derived from the “brain drain” debate over terrestrial migration, as well as the objection that protecting the right to emigrate would be financially ruinous for the lunar state.