Following its latest close flyby of Jupiter – passing just 4,200 km (2,600 mi) above the gas giant’s cloud tops on February 2nd, 2017, NASA’s Juno mission spacecraft is now heading away from the planet once more and the next of its 53.5 day orbits. As I’ve previously reported in these Space Sunday columns, the original plan had been to use one of these close passes over the planet (October 2016), in conjunction with a sustained burn of the spacecraft’s British-built rocket motor, to move it into a short, 14-day period orbit around Jupiter.
However, a potential fault detected within the engine system meant the October burn was cancelled, and since then, engineers had been trying to assess if the issue – a set of faulty valves – could be overcome, and the consequences of attempting an additional engine burn if not. No definitive answer has been found and so, following the February 2nd flyby, the decision was taken to cancel all plans for the engine burn and leave the spacecraft in its current 53.5 day orbit around Jupiter.
Doing so doesn’t compromise the overall mission objectives, but it does reduce the number of close passes over Jupiter the vehicle can make. If the reduced orbital period had been possible, the spacecraft would have made some 30 close flybys over Jupiter’s cloud tops during the primary mission period, set to end in July 2018. Remaining in the 53.5 day orbit means it will only make around 12 such close flybys in the same period.
A positive point with the spacecraft remaining in its more extended orbit is that it will spend less time within the harsher regions of Jupiter’s radiation belts, and could thus remain active for longer than the primary mission period – and mission planners are already considering applying for further funding to allow the mission to extend beyond July 2018. It also means that the spacecraft will be able to engage in additional science activities.
The close encounters with Jupiter have already allowed the spacecraft to probe deep within the planet’s cloud belts and discover they extend far deeper into the planet’s atmosphere than had been imagined, and that Jupiter’s magnetic field and auroras are more powerful than previously thought.
“Juno is providing spectacular results, and we are rewriting our ideas of how giant planets work,” Juno principal investigator Scott Bolton, of the South-west Research Institute in San Antonio, Texas, said of the decision to leave the spacecraft in its current orbit. “The science will be just as spectacular as with our original plan.”
NASA Considering Crewed Option for Orion / SLS First Launch
NASA is considering making the first launch of its new Space Launch System (SLS) rocket, currently slated for September 2018, a crewed mission.
Under the agency’s existing plans, the first launch of the new rocket, topped by an Orion Multi-Purpose Crew Vehicle and dubbed Exploration Mission 1 (EM-1), would have seen SLS send an uncrewed Orion vehicle to the Moon and back, with around 6 days spent in lunar orbit. A crewed flight of the SLS / Orion combination would not take place until at least 2021, when crew would use Orion to rendezvous to a small asteroid previously captured via robotic means and moved to an extended orbit around the Moon – an idea which has garnered a certain amount of criticism from politicians.
If approved, the new proposal – put forward by NASA’s Acting Administrator, Robert Lightfoot – would see the planned EM-1 mission pushed back to 2019 (allowing the Orion vehicle to be outfitted with the crew lift support and flight systems) and flown with a crew of two. While this would mean a delay in the initial launch of SLS / Orion, it could ultimately accelerate NASA’s plans, allowing the agency to present a wider choice of crewed missions in the 2020s, and respond to criticism that it is not doing enough to demonstrate how it plans to achieve a return to the Moon and / or missions to Mars.
Enceladus: Cradle for Life?
On February 17th, 2005 NASA’s Cassini space probe, part of the Cassini / Huygen mission, made its first flyby of Saturn’s moon Enceladus.
Scientists were naturally curious about the 500 km (360 mi) diameter moon, which is the most reflective object in the solar system, but assumed it was essentially a dead, airless world. However, Cassini immediately found this was not the case.
The first thing that happened was the magnetometer on the spacecraft revealed that Saturn’s magnetic field, which envelops Enceladus, was perturbed above the moon’s south pole in a way that didn’t make sense for an inactive world – it was as if there was some interaction with an atmosphere.
In the second flyby, a month later, Cassini found the interaction seemed to suggest a plume of water vapour was rising from the moon. Then, in the third flyby, in July 2005, the probe imaged geysers of water vapour erupting from the moon’s south polar region, and thus Enceladus became the target of intense study. So much so, that while only those initial 3 flybys of the moon had been a part of the primary Cassini /Huygens mission profile, the mission was updated to allow 20 more flyby of the moon.
Today, we know that beneath the mantle of ice enclosing Enceladus there is an ocean of liquid water – the geysers are the results of that water breaking through this ice and jetting into space, giving rise to Saturn’s E-ring in the process. This ocean is likely to be warmed and kept liquid by hydrothermal vents on the sea floor, and these in turn – just like the vents theorised to be on the ocean floor of Jupiter’s Europa – might provide all the ingredients for basic life to arise.
To celebrate the 12th anniversary of Cassini’s discoveries with Enceladus, NASA has released a video documenting those initial findings from 2005.
SpaceX Inaugurates New Era for KSC Pad 39A
One Sunday, February 19th, and after a 24-hour delay, the SpaceX Cargo ReSupply mission 10 (CRS-10), lifted off from Pad 39A at Kennedy Space Centre (KSC), Florida, marking the first tim that the spaceport’s historic Launch Complex 39 had been used since the retirement on the space shuttle in 2011.
The landmark launch complex, home to every Apollo and space shuttle mission, comprises two major paunch facilities: Pad 39A and Pad 39B. The latter will be home to launches for America’s new Space Launch System, while Pad 39A was leased to SpaceX in 2014, and the company has spent 3 years converting it for use with their Falcon 9 and soon-to-fly Falcon Heavy rockets. Eventually, the company hope to use the pad in conjunction with their facilities at the neighbouring Canaveral Air Force Station to make a Falcon launch every three weeks.
Lifting off for CRS-10, which will rendezvous with the International Space Station some time on February 21st or 22nd, occurred at 14:38:59 UTC. It will deliver just over two tonnes of supplies and science experiments to the station. The weather wasn’t great for viewing the launch, but SpaceX did live stream it, and shortly afterwards they issued a shorter video featuring the rocket’s lift-off, and the entire return from space of the first stage, which culminated in a safe touch-down at the SpaceX Landing Zone 1 at Canaveral Air Force Station (formerly Launch Complex 13). It’s a remarkable piece to watch.
Dawn Discovers Building Blocks of Life on Ceres
The joint NASA / ESA Dawn mission to Ceres, which has featured in previous Space Sunday reports, has revealed startling evidence that the “protoplanet”, which the space vehicle has been observing since March 2015, contains some of the building blocks of Life. The discovery of aliphatic compounds on the surface of Ceres was made by an international team of scientists who have been reviewing data from the Visible and Infra-red Mapping Spectrometer (VIMS) aboard the spacecraft.
Aliphatics are a type of organic compound where carbon atoms form open chains that are commonly bound with oxygen, nitrogen, sulphur and chlorine. They were initially identified in a region roughly 1,000 sq km (386 sq mi) region around Ernutet crater in Ceres’ northern hemisphere. Following the initial discovery, the science team investigated whether the molecules might have been deposited from an external source, such as a comet or carbonaceous chondrite asteroid, but could not find any evidence of this being the case.
Instead, their location on the crater floor, around its rim and in ejecta surrounding the crater suggests they originated within Ceres, a hypothesis supported by smaller traces of the compounds being found around Inamahari Crater, about 400 km (250 mi) from Ernutet.
Their discovery is significant, as they further suggest that organic molecules exist within Ceres, beneath its icy mantle. If so, it might mean that basic life could exist within the protoplanet’s liquid interior in a way that is similar to Jupiter’s Europa and Enceladus, (see above). Further, given that Ceres is believed to have originated 4.5 billion years ago (when the solar system was still in the process of formation), the discovery of the compounds is also significant in that it can shed light on the origin, evolution, and distribution of organic life in the solar system.
Dream Chaser To Fly Hubble Repair Mission?
I’ve previously written about Sierra Nevada Corporation’s (SNC) Dream Chaser mini-shuttle. Originally designed – but not chosen by NASA – to fly crews to / from the International Space Station, it now being developed as a cargo resupply vehicle to help maintain the ISS (see here and here). However, SNC recently put forward a proposal to use the crew variant of the vehicle to fly a servicing mission to the Hubble Space Telescope (HST).
Hubble’s work is largely expected to be overtaken by the James Webb Space Telescope (JWST – (see here and here for an overview of the mission), although Hubble should be able to remain operational through to at least 2030, barring major failures. JWST is due for launch in 2018, but it is an ambitious mission. Not only is the telescope not designed to be serviced / repaired in space, it will also operate in the Sun / Earth L2 position, approximately 1.5 million km (930,000 mi) beyond the Earth, relative to the Sun. Thus, there are fears that if anything goes wrong once it is in operation, or during its launch and 160-day deployment, and if HST is not maintained, Earth could be left without an orbital observatory.
Thus, SNC believe they can offer an insurance policy in offering to fly a potential servicing mission to Hubble, although the idea is not without significant issues of its own. For one thing, Hubble is designed specifically to be serviced within the cargo bay of a space shuttle, where logistics are far easier to manage, and astronauts can use suitable servicing platforms, including the shuttle’s own robotic arm. The much smaller Dream Chaser offers none of these capabilities.
This makes any repair mission an exceptionally complex affair, requiring the astronauts to work without any means to anchor themselves, while also maintaining the Dream Chaser in close proximity to HST to ease the transfer of equipment and tools, but not so close as to risk damage to the telescope. It’s also not clear precisely how far SNC have continued to develop their crewed version of Dream Chaser since the vehicle was dropped from NASA’s Commercial Crew Transportation System programme, or what would be required to bring it up to a status where such a mission could realistically be undertaken.
NASA has yet to provide feedback on the proposal, Although it is understood the idea was also put before the Trump team responsible for handling NASA’s transition to management by the new administration.