Watching the Asteroids

Asteroids are always intriguing. Little planetoids that fly around the solar system in mysterious orbits, often swinging dangerously close to Earth. It’s that element of the unknown as well as the potential threat to life on Earth that always ensures their popularity.

There is a lot of work going on behind the scenes in modelling asteroid orbits and tracking them. The NASA Near-Earth Object Observations Program – dubbed Spaceguard – detects, tracks characterises both asteroids and comets passing by Earth (anything inside 28 million miles of Earth is regarded as Near-Earth). It uses both ground and space-based telescopes. This information is used to predict their paths, and to determine any potential hazard.  At any given moment some of the world’s most massive radar dishes are on the case.

A new space-based asteroid-hunting telescope is being planned. NASA scientists recently tested the Near-Earth Object Camera – a key instrument. That will be interesting to watch for, potentially doing for asteroids what Kepler did for planet-hunting.

One favourite way to get to know an asteroid is hitting it hard with another object (not recommended in personal relationships). Those collisions can tell us a lot about their structural integrity and composition. Trying to get that little probe to actually hit anything travelling at hypervelocity (11,000 km/h or above) is a feat in itself.

Knowing where an asteroid will be, and its structure and composition are vitally important things to know if we plan to move asteroids around or want to explore them for valuable materials.

Potential targets can be quite small – as tiny as 50 metres wide. One little-known complication of creating a scientifically significant impact is that they can also have their own little family of tiny moons orbiting around them. Trying to track down those secondary orbiting bodies can be a challenge, but critical to the success of any ultimate impact.

At least with asteroids you do not have the complication of jets of material firing into space, which you have with comets. These can upset imaging and guidance systems.

One likely candidate is the asteroid 1999 RQ36, which is the target of a NASA mission called OSIRIS-Rex. The currently slated launch date is September 2016, with the ‘landing’ in 2023 (now that’s long-term planning). Not only do the NASA scientists need to co-ordinate the impact, they have to ensure that the OSIRIS-REx spacecraft, with its crucial observing instruments, can monitor the results of the impact from a safe distance. This little craft will do a loop around Mars then close with its target at the rate of 49,000 km/h (8.4 mi/s). Needless to say mission scientists will be executing several deep space manoeuvres to refine its position during its approach. The spacecraft’s own automatic navigation system will take control only two hours from impact, executing three planned corrections at 90min, 30min and 3min from the impactor ‘landing’. At this point the spacecraft will be a mere 2,400 km away from RQ36. Cosmic spitting distance!

Who Shrank the Shuttle?

If you see a picture of the X-37B unmanned spaceplane, you would be forgiven for mistaking it for a slightly modified Space Shuttle. If you look closer you realise it’s a mini-version of a Shuttle, around 9m (29ft) in length and 5 tonnes (11,000 pounds), with a payload of your average pickup truck.

Here is a picture of it in its hanger [CREDIT: space.com].

 X-37B mini shuttle

Looks awesome. I like the V-shaped rear wings. Looking at this I’m thinking all that money spent in Shuttle development wasn’t as wasted as I thought.

Two have been built so far (reportedly), and one has been in orbit around Earth since December, although no one knows exactly what it’s doing up there.

The X-37B went into orbit on top of an Atlas 5 rocket from Florida’s Cape Canaveral on December 11 2012. The current mission is designated Orbital Test Vehicle-3 (OTV-3), as the third classified mission under the US Air Force’s X-37B program.

The little robotic vehicle is on the USAF’s books as USA-240.

The vehicle lands on a strip, just like its bigger (defunct) cousin, but even more impressively it does so autonomously. Pretty cool, huh? I thought maybe I could sneak into the back in a spacesuit for some spacewalking next time it goes up, but then realised I could never hope to pack enough oxy-mix – the little craft was up in orbit for 469 days for OTV-2. That’s a long time to hold your breath.

OTV-2 ended on a special strip at Vandenberg  on June 16 last year, although the jury is out as to whether OTV-3 will end there or back at the good old shuttle strip at Kennedy Space Centre.

Anyone heard anything about what the X-37B’s doing up there?

Power On Voyager

There was quite a bit of celebration this week as Voyager 1 celebrated 35 years sweeping through our solar system. The hard-working little beast – despite its 1970s technology – is still powering on out there. Still propelled by its last gravity slingshot and crusiing on 350 Watts from its Plutonium batteries. It’s a Hell of an achievement, and I have nothing but respect for those NASA and JPL engineers of the bygone era, there attention to detail, dedication and technical know-how.

There was a lot of press over the last week or so with the headlines ‘Voyager Leaves the Solar Sytem’. The fact is no one will really be able to know – except in retrospect – when our silicon-and-alloy ambassador will really cross the Heliopause – the boundary of the Heliosheath where the suns influence stops and the cosmic wind takes over.

What they do know is that the cosmic rays being detected by Voyager have increased quite dramatically in comparison to its prior journey from the inner Solar System. This is a good indication its nearing the Heliopause. It’s only by analysing the data over a long period (and let’s hope old Voyager keeps ticking through the whole process) that the precise ‘boundary’ will be declared.

Amazing achievement though – Voyager is 18 billion kilometers (11 billion mi) from, the Sun. All the while carrying that gold disk with the ‘Sounds of Earth’ . God knows what any alien race will make of that – ‘Hey man, break out the record player. These cats don’t use vinyl.’

I can’t help but imagine the historical tours of the outer Solar System in a century where you speed out from Earth to Oort Cloud in a fast cruiser, snap out of suspension to watch in amazement as the ancient Voyager 1 limps along through the cosmic wind. Or the celebration in around 50,000 years when the little beast finally reaches a star poetically named AC+79 3888.