asteroids — in the next 100 years. the smaller asteroids, this is about 140 metres across _ asteroids, this is about 140 metres across, those are the ones we do not find so _ across, those are the ones we do not find so easily — across, those are the ones we do not find so easily. telescopes look the things— find so easily. telescopes look the things that move in the sky, and they— things that move in the sky, and they are — things that move in the sky, and they are very faint if they are very small— they are very faint if they are very small because they don't reflect the sun's— small because they don't reflect the sun's light _ small because they don't reflect the sun's light unlike the moon which is huge. _ sun's light unlike the moon which is huge. and _ sun's light unlike the moon which is huge, and you can see a shadow on a full moon— huge, and you can see a shadow on a full moon night. but they are so faint— full moon night. but they are so faint that — full moon night. but they are so faint that we don't spot them until they are _ faint that we don't spot them until they are close to us. we might not -et they are close to us. we might not get advanced warning. if we're lucky. — get advanced warning. if we're lucky. we _ get advanced warning. if we're lucky, we would get six months or a year. _ lucky, we would get six months or a year. we _ lucky, we would get six months or a year, we don't want to be grumbling around _ year, we don't want to be grumbling around like — year, we don't want to be grumbling around like headless chickens in that year— around like headless chickens in that year trying to design and plan and build — that year trying to design and plan and build a whole new mission which has never— and build a whole new mission which has never been tested before so this is why— has never been tested before so this is why this _ has never been tested before so this is why this launch and this mission is why this launch and this mission is so _ is why this launch and this mission is so important. it means we have a plan _ is so important. it means we have a plan and _ is so important. it means we have a plan and we — is so important. it means we have a plan. and we are also testing the plan. and we are also testing the plan to— plan. and we are also testing the plan to make sure it works so if this situation arises, we can say, it is ready— this situation arises, we can say, it is ready to— this situation arises, we can say, it is ready to go, let's get it launched _ it is ready to go, let's get it launched and get this fixed. if you have 'ust launched and get this fixed. if you have just joined _ launched and get this fixed. if you have just joined us, _ launched and get this fixed. if you havejust joined us, good - launched and get this fixed. if m. havejustjoined us, good morning, don't panic! you are watching live pictures from a nasa mission which hasjust