Proxima b, the planet discovered orbiting the closest star to our own, Proxima Centauri (see here for more), has been the subject of much speculation regarding its potential habitability (see here for more). Now a new study is underway which may bright us a lot closer to understanding the conditions on the planet.
Located 4.25 light years away, Proxima Centauri is a M-type red dwarf star. Such stars are highly variable and unstable compared to other types of stars, and this might weigh heavily against Proxima b having the right conditions for life to arise. The new study involves a team of astrophysicists from the University of Exeter, England, and staff from the UK’s Meteorological Office, who have been using the latter’s state-of-the-art Unified Model (UM).
Used to study Earth’s atmosphere, with applications ranging from weather prediction to the effects of climate change, the Unified Model allowed the team to simulate what Proxima b might be like if it had a similar atmospheric composition to Earth, and also what it might be like if had a much simpler atmosphere – one composed of nitrogen with trace amounts of carbon dioxide. Last, but not least, they made allowances for variations in the planet’s orbit.
This last point is important because given the planet’s distance from its parent – around 7.5 million km (4.6 million mi) – Proxima b is likely to either be tidally locked so that one face constantly faces its sun, or it is in a 3:2 orbital resonance, rotating three times on its axis for every two orbits around its sun. In the former situation, the main atmospheric gases on the night-facing side would likely freeze, leaving the daylight zone exposed and dry; in the latter, a single solar “day” would last a long time, resulting in the sunward side of the planet being extremely hot and day and the night side very cold and dry.
Taking all of this into account, and using data from previous studies, the UK team found that Proxima b, with either a complex or a simple atmosphere, could have regions where water might exist in liquid form. In addition, any substantive eccentricity in the planet’s orbit around its sun could further increase its potential habitability.
It will still be some time before more can be directly discerned about Proxima b, but it is hoped that the study will help in our understanding of the potential habitability of other exoplanets, and demonstrates how the study of conditions here on Earth can be used to predict what may exist in extra-solar environments. It may also improve our understanding of how our own climate has and will evolve.
US Military “Close” To Awarding Spaceplane Contract
The US Defence Advanced Research Projects Agency (DARPA) is reportedly “close” to awarding a contract to build its XS-1 spaceplane launch vehicle.
Announced in 2013, the XS-1 is intended to provide the US military with the means to rapidly deploy small satellite payloads to Earth orbit using a re-usable first stage and expendable upper stage which may be carried piggyback by the first stage vehicle. The goal of the programme is to provide an uncrewed launch vehicle capable of delivering payloads of up to 2,300 kg (5,000 lb) to orbit, which can be rapidly re-used – the target of the development programme is to have the vehicle complete 10 launches in 10 days. In addition, the vehicle must:
- Be capable of hypersonic flight to Mach 10 (12,250 km/h) or higher
- Lifting an expendable upper stage unit which it can then launch, and which can carry the payload to orbit
- Operate with a launch cost less than 1/10 that of current launch systems (i.e. around US $5 million per flight).
Three groups of companies were awarded initial design concept contracts: Boeing and Blue Origin, Masten Space Systems and XCOR Aerospace, and Northrop Grumman and Virgin Galactic. None of these may be awarded the development contract, which is intended to see the project to a point where test flights could commence in 2020.
To be successful, the vehicle will make use of advanced materials, cryogenic tanks, durable thermal protection, and modular subsystems. These, coupled with a reliable, re-usable propulsion system, would make it possible for the vehicle to achieve the hoped-of low-cost, rapid launch and re-use capability.